K8AC-CT200L - OMRON - Datasheet.Live

Digital Heater Element Burnout Detector

K8AC-H

A high-precision Heater Element

Burnout Detector compatible with a

wide-range of heater control methods.

• Push-in terminals reduce the workload.

• Scaling

• NPN or PNP equivalent output.

•

Lineup includes models compatible with many heater control methods,

including ON/OFF control, phase control, and cyclic control.

• High-precision heater burnout alarm with digital measurement.

• Contributes to preventative maintenance.

• If the gate function is disabled, the gate input can be used as an

undercurrent/overcurrent relay or for motor or lamp loads.

• Undercurrent detection values can be set separately for CT1 and

CT2. *

• CE marking and cUL certified.

*The overvoltage detection value is the same for the CT1 and CT2. Also, there is

one undercurrent output.

Note: 1. Consult with your OMRON representative before using the K8AC with

phase control or cyclic control under the following conditions.

• Using multiple heaters with different heater capacities

• Using heaters with varying heater resistance (e.g., halogen heaters)

2. The K8AC-H is designed to monitor for element burnouts on heaters

controlled with power regulators that used a three-alarm method.

Normal monitoring is not possible for circuits that use a power regulator with a six-alarm method.

Features

High-precision Heater Burnout Alarms with

High-resolution Digital Measurement

Burnout Alarm Possible for One of Multiple

Heater Elements

Heater burnout is detected by digitally processing minor current

fluctuations.

Push-in Terminals for Reduced Wiring Work

Push-in terminals have no screws to come loose, which eliminates

the need to control screw tightening torque and retighten screws and

helps to reduce your workload.

Easily connect terminals using ferrules with insulation sleeves.

Easy Scaling Using the External CT Ratio

and Number of CT Passes

Easily set the scaling just by inputting (1) the CT ratio and (2) the

number of CT passes.

Wide Current Input Range: 0.200 to 200.0 A AC.

For the most recent information on models that have been certified for

safety standards, refer to your OMRON website.

K8AC-H

Digital Heater

Element Burnout

Detector

E5@@

Digital

Temperature

Controller

Three-phase

delta-connected heater

G3PE

Three-phase

SSR

Current Transformer

RST

Electric

oven

K8AC-CT@

Current Transformer

(2) Number of CT passes

(1) CT ratio

Heater

External

@A/1A

K8AC-H

Compatible with Various Heater Control

Methods

Models with heater burnout alarms for ON/OFF control, phase

control, and cyclic control have been added to the lineup.

Check the current input range, connected CT, and relay output type

before selecting the model from the product specifications.

Note: Both single-phase and three-phase heaters are supported.

Overcurrent and SSR Failure Detection from

Heater Layer Short Circuits.

•Overcurrent can be detected from layer short circuits in addition to

providing heater burnout alarms with overcurrent detection

settings.

•SSR short circuit failures and SSR open circuit failures are

detected by monitoring the heater current and the control outputs

from the temperature controller.

•Detecting SSR failures enables promptly discovering that

temperature control has failed.

Heater Burnout Alarms for Cyclic Control or

Phase Control Heaters

(K8AC-H@@P@)

The burnout detection value is shifted according to the

control output value from the temperature controller.

•Analog control is performed on the output power according to the

temperature controller's current output (4 to 20 mA) when phase

control or cyclic control is used.

•Heater burnout alarms are stable with the K8AC-H because the

heater burnout alarm values are linked with the control output

value from the temperature controller.

Compatible with Gradient Settings of Pow er Controllers

When using gradient settings with a power controller, set a gate

current level that is suitable for the gradient settings.

Note: Set the heater burnout alarm value based on the current at the

heater's rated input.

The transistor output from the K8AC-H2@@N

can be used as either an NPN open-collector

output or a PNP equivalent output.

The transistor output of the K8AC-H2@@N uses a photocoupler for

isolation with the internal circuits, and so either an NPN open-

collector output or a PNP equivalent output can be used.

Preventive Maintenance

The run time can be measured by the K8AC-H.

Managing the run time history until burnouts occur is useful for

diagnosis and preventative maintenance for equipment.

Count the Total Number of Alarms Output

Set the upper and lower limits to count the total number of alarms that

have been output.

Heater current

4 mA

Heater current

Heater burnout

alarm value

7 mA 20 mA

Control output from temperature controller

Heater Burnout Alarm Value

The heater burnout alarm value shifts

according to the control input (4 to

20 mA) from the temperature controller.

Gradient setting: 100%

Gradient setting: 50%

Control signal

100%

Output current

Measurement range

DetectedNot detected

4 mA 14 mA 20 mA

Operation gate current level

NPN Output PNP Equivalent Output

Load

Load power supply Load power supply

Load

K8AC-H

Model Number Structure

Model Number Legend

Ordering Information

Digital Heater Element Burnout Detectors

Models with Push-in Terminals (Power Input: Screw Terminals)

Note: Consult with an OMRON representative if multiple heaters with different capacities are to be connected in parallel or if the heater resistance

will vary.

Optional Products (Sold Separately)

Current Transformers

Note: When selecting a Current Transformer, make sure that the rated current of the heater does not exceed the rated upper limit or the rated

current of the Current Transformer.

Power

supply

voltage

Heater control

method

Input

specifica-

tions

Output specifi-

cations

Com-

munica-

tions

output

Current input range

0.200 to 2.200 A 2.00 to 22.00 A 20.0 to 200.0 A

100 to

240 VAC

ON/OFF control

SSR control

Two

current

inputs

(for either

single-

phase or

three-

phase)

One relay output

RS-485

K8AC-H21CC-FLK K8AC-H22CC-FLK K8AC-H23CC-FLK

Two transistor

outputs K8AC-H21CN-FLK K8AC-H22CN-FLK K8AC-H23CN-FLK

Phase control

Cyclic control

One relay output K8AC-H21PC-FLK K8AC-H22PC-FLK K8AC-H23PC-FLK

Two transistor

outputs K8AC-H21PN-FLK K8AC-H22PN-FLK K8AC-H23PN-FLK

Applicable Current Transformer K8AC-CT20S or K8AC-CT20L K8AC-CT200 or

K8AC-CT200L

Current

Transformers

(sold separately)

Through-hole diameter Rated current Installation method Model

5.8-mm dia.

0.200 to 22.00 A

Surface-mounted with screws K8AC-CT20S

12-mm dia.

Rear-surface mounted with screws

Binding band K8AC-CT20L

20.0 to 200.0 A Rear-surface mounted with screws

Binding band K8AC-CT200

30-mm dia. 20.0 to 200.0 A Surface-mounted with screws K8AC-CT200L

12345 6 7

K8AC-H2@@@ -FLK 100-240VAC

1. Basic Model

K8AC-H: Digital Heater Element Burnout Detector

2. Product Type

2: Push-in terminals (Power Input: Screw Terminals.)

3. Current Input Range

1: 0.200 to 2.200 A

2: 2.00 to 22.00 A

3: 20.0 to 200.0 A

4. Heater Control Type

C:ON/OFF control (SSR or contactor)

P: Phase control or cyclic control

5. Output Type

C: Contact output (one SPDT relay contact output)

N: Transistor outputs (Two outputs: either NPN open-collector

output or PNP equivalent output can be used.) *

*K8AC-H2@@N only.

6. Communications Specifications

FLK: RS-485

7. Power Supply Voltage

100-240VAC: 100 to 240 VAC

K8AC-H

Specifications

Ratings

*1. The gate input enables correct measurement by syncing to heater control.

When using it with ON/OFF control, receive the relay contact output from the temperature controller or other controller with a 24-VDC auxiliary

relay and then use this signal as the gate input signal to the K8AC.

The gate function can also be disabled. If it is disabled, the gate input can be used as a normal undercurrent/overcurrent relay.

*2. When using the K8AC-H for a 380 to 480-V AC power supply circuit, use a step-down transformer. Contact your OMRON representative for

information on transformers.

*3. Order the Current Transformers separately.

Heater control method Models for ON/OFF control (e.g., SSRs or contactors) Models for phase control and cyclic control

Item Model K8AC-H2@C@-FLK K8AC-H2@P@-FLK

Power supply voltage 100 to 240 VAC (50/60 Hz) *2

Operating voltage range 85% to 110% min. of the rated power supply voltage (85 to 264 V)

Power consumption

(at max. load) 35 VA max.

Applicable circuits Single-phase or three-phase (with same model)

Applicable control methods

ON/OFF control (e.g., temperature controller with relay output)

SSR control (e.g., temperature controller with voltage output)

Cyclic control and phase control (e.g., temperature controller with current output)

Input signal and applicable Current

Transformer

Current measurement via two special Current Transformers (Burnout alarm set value can be set separately for each Current

Transformer.)

Refer to Current Measurement Ranges by Model on page 6 for information on the current measurement range and

applicable Current Transformer.

Measurement method Effective value calculation based on instantaneous measurement value

Gate input

signal *1

ON/OFF control Voltage = 12/24 VDC (continuous input possible to 30 VDC)

Input impedance = 4 kΩ min. ---

SSR control

ON voltage: 9.6 VDC max., OFF voltage: 1 VDC min.

Minimum voltage pulse ON time for burnout detection:

200 ms min.

Input impedance = 4 kΩ min.

---

Cyclic and phase con-

trol ---

4 to 20 mA DC (Burnout detection is possible for an input of

7 mA or greater.)

Input impedance = 50 Ω max.

Outputs

Relay contact outputs:

K8AC-H2@@C-FLK

One SPDT relay contact output

Same output used for heater burnout, SSR short circuit, SSR open circuit, and heater layer short circuit alarms.

0.3 A at 125 VAC (resistive load), 1 A at 30 VDC (resistive load)

Maximum switching capacity: 37.5 VA, 30 W

Mechanical durability: 50 million operations min., electrical durability: 100,000 operations min.

Transistor outputs:

K8AC-H2@@N-FLK

Two transistor outputs: Can be used either NPN open-collector outputs or PNP equivalent outputs.

One ALM output: Outputs heater burnout alarm or heater layer short circuit alarm.

One SSR error output: Outputs SSR short circuit or SSR open circuit detection.

12 to 24 VDC, 50 mA

OFF leakage current: 100 μA max., ON residual voltage: 1.5 V max.

Communications RS-485 1200, 2400, 4800, 9600, 19200 bps (CompoWay/F)

Indication method 7-segment digital display: No. of display digits: 4 (red)

LED status indicators: RUN (green), ADJ (orange), SET (orange), GATE (orange), SSR (orange) and ALM (orange)

Main functions

Heater burnout alarm, heater layer short circuit alarm, SSR short circuit detection, SSR open circuit detection, voltage

fluctuation compensation, output ON-delay timer, energy-saving mode, key protection, and power supply voltage

measurement

Ambient

temperature

Operating −10 to 55°C (with no icing or condensation)

Storage −25 to 65°C (with no icing or condensation)

Ambient

humidity

Operating 25% to 85% (with no condensation)

Storage 25% to 85% (with no condensation)

Altitude 2,000 m max.

Accessories Instruction sheet

Case material PC (Polycarbonate)

Case color N1.5 (clear black)

Mounting method Mounting to a DIN Track

K8AC-H

Characteristics

Note: For phase control, the accuracy is the value when the control value of the power regulator is 100% (when the waveform of the heater current

is a sine wave). “rdg” is the error in the reading of the input current.

*1. The Current Transformers are sold separately.

*2. The values for measurement current apply when the K8AC-H is used in combination with a Current Transformer.

Heater control method Models for ON/OFF control (e.g., SSRs or contactors) Models for phase control and cycle control

Item Model K8AC-H2@C@-FLK K8AC-H2@P@-FLK

Heater current

input

(at 10 to 30°C)

category II

Input range

K8AC-H21@@: 0.200 to 2.200 A (Current Transformer: K8AC-CT20S (5.8 dia.), K8AC-CT20L (12 dia.) *1)

K8AC-H22@@: 2.00 to 22.00 A (Current Transformer: K8AC-CT20S (5.8 dia.), K8AC-CT20L (12 dia.) *1)

K8AC-H23@@: 20.0 to 200.0 A (Current Transformer: K8AC-CT200 (12 dia.), K8AC-CT200L (30 dia.) *1)

Measurement accuracy ±3% rdg ±10 digits max. *2±6% rdg ±10 digits max. (at control level of 100%) *2

Voltage

fluctuation

compensation

category II

Input range 85 to 264 VAC

Measurement accuracy ±3% rdg ±10 digits max.

Gate input Input range 0 to12 VDC or 0 to 24 VDC

ON: 9.6 VDC max., OFF: 1 VDC min. 4 to 20 mA DC

Display cycle Selectable: Immediate, 0.2 s, 0.5 s, 1.0 s

Output ON-delay time 0.0 to 99.9 s (operating time)

Soft start time 0.0 to 99.9 s (used when using the soft start function of a Power Controller)

Output reset method Automatic reset

Alarm hysteresis 1 to 999 digits

Output response time 500 ms max. 3.5 s max.

Insulation resistance

20 MΩ min.

Between terminals and case

Between power supply terminals/CT primary terminals and gate input terminals/communications terminals

Between power supply terminals/CT primary terminals and output terminals

Between gate input terminal/communications terminals and output terminals

Dielectric strength

2,000 V for 1 min

Between terminals and case

Between power supply terminals/CT primary terminals and gate input terminals/communications terminals

Between power supply terminals/CT primary terminals and output terminals

Between gate input terminal/communications terminals and output terminals

Noise immunity Power supply terminals normal/common mode: ±1,500 V (startup 1-ns square-wave noise, pulse width: 1 μs/100 ns)

Vibration resistance Vibration: 10 to 55 Hz, Acceleration: 50 m/s2 for 5 min with 10 sweeps each in X, Y, and Z directions

Shock resistance 150 m/s2 (100 m/s2 for relay contacts) 3 times in 6 directions in X, Y, and Z directions

Maximum

allowable input

Current Transformer

primary current

K8AC-H21@@: 4 A: 30 s, 12 A: 1 s

K8AC-H22@@: 40 A: 30 s, 120 A: 1 s

K8AC-H23@@: 400 A: 30 s, 1,200 A: 1 s

Gate signal: 4 to 20 mA 40 mA DC continuous

Voltage pulse gate in-

put 30 VDC continuous

Input imped-

ance

Gate signal: 4 to 20 m 50 Ω max.

Voltage pulse gate in-

put 4 kΩ min.

Weight Approx. 200 g

Memory protection Non-volatile memory (number of writes: 100,000 operations)

Installation environment Installation Category 2, Pollution Class 2

Approved standards UL61010-1 and CAN/CSA C22.2 No.61010-1

EN 61010-1 (IEC 61010-1)

EMC

EMI: EN61326-1 Industrial electromagnetic environment

Radiated Interference Electromagnetic Field Strength: EN55011 Group 1, class A

Noise Terminal Voltage: EN55011 Group 1, class A

EMS: EN61326-1 Industrial electromagnetic environment

ESD Immunity: EN61000-4-2: 4 kV (contact discharge)

8 kV (air discharge)

Electromagnetic Immunity: EN61000-4-3: 10 V/m 1 kHz sine wave amplitude modulation

(80 MHz to 1 GHz)

Fast Transient Burst Immunity: EN61000-4-4: 2 kV (power line)

1 kV (I/O signal line)

Surge immunity: EN61000-4-5: 1 kV (line to line, power line)

2 kV (line to ground, power line)

Conducted Noise Immunity EN61000-4-6: 3 V (0.15 to 80 MHz)

Voltage Dip/Interrupting Immunity EN61000-4-11:0.5 cycle, 0.180°,100% (rated voltage)

K8AC-H

Current Measurement Ranges by Model I/O Ratings

Relay Contact Output

Transistor Output

Communications Specifications

200 A

Model

20 A

2 A

100 A

Current

measure-

ment

range

Current

Trans-

former

Item

K8AC-H21@@-FLK

0.200 to 2.200 A AC

K8AC-CT20S: 5.8-mm through-hole diameter

K8AC-CT20L: 12-mm through-hole diameter

K8AC-H22@@-FLK

2.00 to 22.00 A AC

K8AC-H23@@-FLK

20.0 to 200.0 A AC

K8AC-CT200:

12-mm through-hole

diameter

K8AC-CT200L:

30-mm through-hole

diameter

2.200 A

2.00 A

22.00 A

20.0 A

200.0 A

0.200 A

Item Load Resistive load (cosφ = 1)

Rated load 125 VAC, 0.3 A, 30 VDC, 1 A

Maximum contact voltage 125 VAC, 60 VDC

Maximum contact current 1 A

Maximum switching capaci-

ty 37.5 VA, 30 W

Minimum applicable load

(failure rate P value, refer-

ence value)

5 VDC, 10 mA

Mechanical life expectancy 50,000,000 operations min. (at a switching

frequency of 18,000 times/h)

Electrical life expectancy

(Ambient temperature con-

dition: 20°C)

100,000 operations min. (at rated load and

switching frequency of 1,800 times/h)

Maximum load voltage 12 to 24 VDC (+10%, −15%)

Maximum load current 50 mA

OFF leakage current 100 μA max.

ON residual voltage 1.5 V max.

Item Communications RS-485

Transmission method Two-wire, half-duplex

Synchronization method Start-stop synchronization

Baud rate 1,200, 2,400, 4,800, 9,600, or 19,200 bps

Transmission code ASCII

K8AC-H

Connections

Terminal Arrangement

K8AC-H2@@@-FLK

Output Circuits

Contact Outputs

Note: For contact outputs, the same outputs are used for SSR error

and for heater burnouts and heater layer short circuit alarm

outputs.

Transistor Output

K8AC-H2@@N-FLK

The transistor output of the K8AC-H2@@N uses a photocoupler for

isolation with the internal circuits, and so either an NPN open-

collector output or a PNP equivalent output can be used.

CT1 CT2 Linear current

4 to 20 mA DC RS-485

8 9 10

7 8 9 10 11 12 13 14

Voltage pulse

12 VDC or

24 VDC

K8AC-H2@C@

Gate input

K8AC-H2@P@

11 12 13 14

Communications Current inputs

1 2

Power supply voltage

100 to 240 VAC

A(−) B(+)

COM

125 VAC,

0.3 A AC

30 VDC,

1 A DC

12 to 24 VDC,

50 mA DC

4 5 6

5 6

Outputs

K8AC-H2@@N K8AC-H2@@C

1 2 3 4 5 6

12 to 24 VDC,

50 mA DC

3 4

Terminals Name Description Applicable models

1 to 2 Power supply voltage Connect to the operating power supply. All models

3 to 4,

5 to 6 Outputs

Outputs SSR open or short circuit detection results.

Outputs heater burnout or layer short circuit detection results.

K8AC-H2@@N

(transistor output)

5, 6 to 4 Outputs an OR of the status of all alarms. K8AC-H2@@C (relay output)

7 to 8 Current inputs Connect to CT1. Current input from CT1 secondary-side output. All models

9 to 10 Connect to CT2. Current input from CT2 secondary-side output.

11 to 12 Gate input Connect to gate signal (voltage pulse). K8AC-H2@C@

Connect to a 4 to 20-mA gate signal. K8AC-H2@P@

13 to 14 Communications Connect to host device for RS-485 communications. All models

Note: 1. Terminals 4 to 6:

Alarm output

terminals. Depend

on the output type

(relay contact

output or transistor

output).

2. Terminals 11 and

12: Gate input

terminals. Depend

on the heater

control type (ON-

OFF/SSR control

or cyclic/phase

control).

CT2

CT1

A/D

conversion

−

A/D

conversion

−

Current Input Circuits

CT Inputs (Heater Current)

COM

Relay

drive

circuit N.C. contact

N.O. contact

+12 V

SSR alarm output

Heater burnout,

heater layer short circuit,

overcurrent alarm output

Transistor

drive

circuit

Transistor

drive

circuit

NPN Output PNP Equivalent Output

Load

Load power supply Load power supply

Load

K8AC-H

External Connection Example

Wiring Method When Using the K8AC-H with SSR Control Heaters

Wiring Method When Using the K8AC-H with ON/OFF Control Heaters

Transistor Output

K8AC-H2@@N-FLK

SSR

CT2

CT1

78 910 1112

13 1412

RS-485

Heater

Power supply

Temperature

Controller

(DC voltage output)

Operation Description

• If the heater current detected at either CT1 or CT2 falls below the

burnout alarm set value, an alarm is output. The burnout alarm set

value can be set separately for CT1 and CT2.

No burnout alarm is output, however, when the temperature con-

troller control output is OFF.

Burnouts are detected only while the temperature controller control

output is being input to the gate input terminals (11 and 12).

Faulty outputs do not occur because heater burnout detection is

linked with the temperature controller.

• The minimum burnout detection time is 200 ms. Shorter burnouts

are not detected.

•

Turn ON the voltage fluctuation compensation function (default: OFF)

to detect power supply voltage fluctuations and automatically compen-

sate the burnout alarm value. Also, turn ON the voltage fluctuation

compensation function to detect minor current fluctuations.

Correct Usage

•

Always take the power supply voltage from the primary side of the SSR.

•Use temperature controllers with a 12 or 24-VDC voltage output

(30 VDC max.).

• CT1 and CT2 are special products. Use the K8AC-CT@@.

• The CTs do not have polarity.

• Connect only one CT for single-phase heaters.

• Connect two CTs for three-phase heaters.

• For three-phase heaters, always set the burnout alarm set values

for both CT1 and CT2.

Transistor Output

K8AC-H2@@N-FLK

CT2

CT1

78 910 1112

13 1412

RS-485

Heater

Power supply

Contactor

Temperature

Controller

(relay output)

24-VDC

power supply

Operation Description

• If the heater current detected at either CT1 or CT2 falls below the

burnout alarm set value, an alarm is output. The burnout alarm set

value can be set separately for CT1 and CT2.

No burnout alarm is output, however, when the temperature con-

troller control output is OFF.

Burnouts are detected only while the temperature controller control

output is being input to the gate input terminals (11 and 12).

Faulty outputs do not occur because heater burnout detection is

linked with the temperature controller.

•The minimum burnout detection time is 200 ms. Shorter burnouts

are not detected.

•

Turn ON the voltage fluctuation compensation function (default: OFF)

to detect power supply voltage fluctuations and automatically compen-

sate the burnout alarm value. Also, turn ON the voltage fluctuation

compensation function to detect minor current fluctuations.

Correct Usage

•

Always take the power supply voltage from the primary side of the SSR.

• Use a temperature controller with relay output.

•The input to the gate input terminals (11 and 12) must be a DC volt-

age input, so wire the 24-VDC power supply as shown in the dia-

gram to the left.

• CT1 and CT2 are special products. Use K8AC-CT@@.

• The CTs do not have polarity.

• Connect only one CT for single-phase heaters.

• Connect two CTs for three-phase heaters.

• For three-phase heaters, always set the burnout alarm set values

for both CT1 and CT2.

K8AC-H

Wiring Method When Using the K8AC-H with Cyclic Control Heaters

Wiring Method When Using the K8AC-H with Phase Control Heaters

SSR SSR

CT2

CT1

78 910 1211

13 1412

RS-485

Transistor Output

K8AC-H2@@N-FLK

Heater *

Power supply

G32A-EA

Cyclic

Control Unit

Temperature

Controller

4 to 20 mA current output

Operation Description

• If the heater current detected at either CT1 or CT2 falls below the

burnout alarm set value, an alarm is output. The burnout alarm set

value can be set separately for CT1 and CT2.

No burnout alarm is output, however, when the temperature con-

troller control output is OFF.

Burnouts are detected only while the temperature controller control output

is being input to the gate input terminals (11 and 12). Burnout is detected

with no errors because the automatic adjustment of burnout alarm level is

linked to the temperature controller control output (4 to 20 mA).

•Burnout is detected when control outputs from the temperature con-

troller are 7 mA min.

Correct Usage

•

Always take the power supply voltage from the primary side of the SSR.

• Use a temperature controller with a 4 to 20-mA current output.

• When you adjust the set value for the burnout alarm, make sure

that you make the setting with the temperature controller's control

output at a 100% output.

The burnout detection value is the detection value at 100% output.

Therefore, correct operation will not be possible if the setting is

made based on a measurement value when the output is not 100%.

• CT1 and CT2 are special products. Use K8AC-CT@@.

• The CTs do not have polarity.

• Connect only one CT for single-phase heaters.

• Connect two CTs for three-phase heaters.

• For three-phase heaters, always set the burnout alarm set values

for both CT1 and CT2.

*Consult with your OMRON representative if multiple heaters are connected

in parallel different heater capacities, or if a heater with varying heater

resistance is used.

CT2

CT1

78 910 1211

13 1412

RS-485

Transistor Output

K8AC-H2@@N-FLK

Heater *

Power supply

Power

Regulator

Temperature

Controller

4 to 20 mA current output

Operation Description

• If the heater current detected at either CT1 or CT2 falls below the

burnout alarm set value, an alarm is output. The burnout alarm set

value can be set separately for CT1 and CT2.

No burnout alarm is output, however, when the temperature con-

troller control output is OFF.

Burnouts are detected only while the temperature controller control

output is being input to the gate input terminals (11 and 12).

Burnout is detected with no errors because the automatic adjust-

ment of burnout alarm level is linked to the temperature controller

control output (4 to 20 mA).

•Burnout is detected when control outputs from the temperature con-

troller are 7 mA min.

Correct Usage

•Always take the power supply voltage from the primary side of the

contactor.

• Use a temperature controller with a 4 to 20-mA current output.

• When you adjust the set value for the burnout alarm, make sure

that you make the setting with the temperature controller's control

output at a 100% output (20 mA).

The burnout detection value is the detection value at a 100% out-

put. Therefore, correct operation will not be possible if the setting is

made based on a measurement value when the output is not 100%.

•Adjust the burnout alarm set value at a 100% output for gradient

settings as well.

•If using the soft startup function with a power regulator, set the soft

startup function on the K8AC-H as well, to prevent malfunctions.

• CT1 and CT2 are special products. Use K8AC-CT@@.

• The CTs do not have polarity.

• Connect only one CT for single-phase heaters.

• Connect two CTs for three-phase heaters.

• For three-phase heaters, always set the burnout alarm set values

for both CT1 and CT2.

• When using the power regulator's gradient settings, change the

operation gate current level so that the heater current value is

within the measurement range. (The initial value is 7 mA.)

For details on operating methods, refer to pages 16 to 18.

*Consult with your OMRON representative if multiple heaters are connected

in parallel different heater capacities, or if a heater with varying heater

resistance is used.

K8AC-H

Heater Connection Methods and Current

Depending on the heater connection method, the current when an error occurs will be as shown in the following table. Refer to this table when

determining burnout alarm set values.

Note: This is the current for when a 200-V, 1-kW heater is used for single-phase or three-phase operation.

Rate of Change for Currents with Parallel Heaters

The following table shows the current change ratios when multiple heaters of the same capacity are connected in parallel and one of the heater

elements burns out. Use this table for reference when making corrections.

If five single-phase heaters are connected in parallel, the current change when burnout occurs is 20% per heater.

For example, if the current for a single heater is low and the change ratio is very slight, it may not be detected. Therefore take into account the

detection accuracy for the total current when selecting the number of heaters to be connected in parallel.

Note: 1. The figures in the above table show the current change ratios when burnout occurs for one heater connected in parallel.

2. The numbers represent the current ratio after one heater burns out, with the current prior to the burnout (i.e., the normal current) taken

as 1.

3. In actual operation there may be effects from factors such as load (heater) imbalances, so conduct an actual test for confirmation before

making adjustments if the current change ratio between normal and abnormal operation is slight.

4. Consult with your OMRON representative if multiple heaters are used with different heater capacities.

Normal condition Abnormal condition

Single-phase

Three-

phase

Delta

connection

Star

connection

Connection n=1 n=2 n=3 n=4 n=5

Single-

phase

With one heater

burned out,

I is 0.

0.5 0.67 0.75 0.8

Star

connection

Current in burned-

out phase

With one heater

burned out,

I is 0.

0.6 0.75 0.82 0.86

Current in other

phases 0.87 0.92 0.95 0.96 0.97

Delta

connection

Current in lines

near burned-out

phase (Same as 2-

phase.)

0.58 0.77 0.84 0.88 0.91

Current in other

phases 11111

200 V

5 A

1 kW

0 A

200 V

1 kW

8.7 A

200 V

(5 A × 3 )

7.5 A

)

(5 A × 3 ×

5 A

8.7 A

)

(5 A × 3 ×

200 V

1kW

1 kW

2.9 A

200 V

)

(5 A ×

2.5 A

)

(5 A × 3

1×

2.5 A

)

(5 A × 3

1×

200 V

1 kW

5 A

8.7 A

5 A

200 V

(5 A × 3 = 8.7 A) 1

2.5 A

(5 A ×)

2(5 A × 1)

5 A

n heaters

INumber of

heaters per

phase = n

Number of heaters

per phase = n

K8AC-H

Operation

Main K8AC-H Functions

The K8AC-H is a digital heater burnout detector that detects heater burnout by measuring the heater current from various power supply systems.

The K8AC-H provides the following functions.

Applicable Heater Control Methods

The following heater control methods can be used.

ON/OFF Control (Contactor/SSR)

Cyclic Control

Phase Control (Applicable to 4 to 20 mA Current-output

Temperature Controllers)

Heater Burnout Alarm

The preset burnout detection value is compared with the heater

current and an alarm is output accordingly.

Error Detection

The following errors are detected according to status.

Heater Layer Short Circuit Detection (overcurrent

detection).

Layer short circuits can be detected in the heater.

The preset overcurrent detection set value is compared with the

heater current and an alarm is output accordingly.

SSR Short Circuit Detection

If current is measured when there is no gate input, an SSR short

circuit error is detected and an alarm is output.

SSR Open Circuit Detection

If current is not measured during gate input, an SSR open circuit error

is detected and an alarm is output.

1 to 99 s

OFF

0.2 to 3.0 s

OFF

Half cycle

OFF

500 ms 100 ms

Current

Set value

Alarm

Transistor output models: ALM indicator lit, ALM transistor output

Relay output models: ALM indicator lit, OR of all detection status output

Transistor output models: ALM indicator lit, ALM transistor output

Relay output models: ALM indicator lit, OR of all detection status output

Set value

Current

Alarm

Gate input

Current

measurement

Alarm

Transistor output models: SSR indicator lit, SSR transistor output

Relay output models: SSR indicator lit, OR of all detection status output

Gate input

Current

measurement

Alarm

Transistor output models: SSR indicator lit, SSR transistor output

Relay output models: SSR indicator lit, OR of all detection status output

K8AC-H

Voltage Fluctuation Compensation

The voltage fluctuation compensation function automatically adjusts

the burnout alarm value of the K8AC-H according to voltage

fluctuations in the heater circuit.

The operating value for burnout detection when multiple heaters are

connected is set very close to the normal value. Thus, a false burnout

alarm output will occur if there is a voltage drop in the heater circuit.

The voltage fluctuation compensation function prevents this type of

false output.

Example: Voltage Drop from 100 V to 95 V in the Heater Circuit

Conditions:

Voltage fluctuation compensation standard value = 100 V

Burnout alarm set value = 10.0 A

If the power supply voltage drops from 100% to 95%, the

operating value will also reduced from 100% to 95%.

Burnout alarm operating value = 10.0 A × 95% = 9.5 A

Gate Input

The gate input provides a sync signal used to link burnout detection

to the control output of the temperature controller.

For SSR control, the voltage output pulse from the temperature

controller is input.

For ON/OFF control, 24 VDC linked to a relay contact of the

temperature controller is input.

For cyclic or phase control, a 4 to 20-mA control signal is input.

If there is no gate input for a Heater Element Burnout Detector, a

heater burnout alarm would be falsely output when the voltage output

pulse from the temperature controller turns OFF, and there would be

no way to tell whether it was a false output.

Note: The gate input function can be disabled. If it is disabled, Heater

Element Burnout Detector operation will not be linked to the

temperature controller control signal. (The gate input can be

used as a simple undercurrent relay.)

Power-saving Operation

If there are no key operations performed within a preset time period,

the display automatically turns OFF.

Output Operation Time Charts

Heater Burnout and Heater Layer Short Circuit

(Overcurrent) Alarms

SSR Short/Open Circuit Alarm

Using the Power Regulator's Grad ient Settings

The power regulator's gradient settings can be used to prevent

malfunction by setting the operation gate current level. The

relationship between the gradient settings and output current

depends on the power regulator manufacturer and model, so be sure

to check the characteristics of the power regulator being used before

setting.

Setting Example

Initial setting: 7 mA

When the power regulator's gradient settings are changed, the

operation gate current level is set so that the output current is within

the measurement range. (In the following diagram, 14 mA is set.)

Using Halogen or Other Heaters with Varying

Resistance during Phase and Cyclic Control

When phase control is used with halogen heaters or other pure metal

heaters, the heater resistance fluctuates according to the control

level. As a result, high-precision detection of heater burnout is not

possible. The effect on the heater and setting methods depends on

the heater being used. Therefore, consult with your OMRON

representative before using a heater with varying resistance values.

Halogen Heater Resistance Fluctuation Example

In the following example, burnout of one element in a six-element

heater can be detected at a control level of 20 mA, but detection is not

possible due to the effect of fluctuating resistance if the control level

is any lower.

Power Save Mode

Standby Time

Heater burnout set value

Heater current

Alarm hysteresis

Heater layer short circuits

Overcurrent set value

ALM indicator lights. ALM indicator lights.

Alarm output

SSR open-circuit

SSR indicator lights. SSR indicator lights.

Alarm output

SSR short-circuit

4 mA

100%

7 mA 20 mA

Output current

Measurement range

Gradient

setting 100%

Control signal

Not detected Detected

4 mA 14 mA 20 mA

100%

Output current

Measurement range

Gradient

setting 100%

Gradient

setting 50%

Control signal

Not detected Detected

7 mA 20 mA4 mA

0 Ω

2 Ω

4 Ω

6 Ω

8 Ω

Heater resistance

Detectable range

Three elements

burned out

One element

burned out

Threshold

Normal

(six elements in parallel)

Control signal

K8AC-H

Nomenclature

Nomenclature and Operations

*Check the specific status using the alarm display parameters on the

main display.

Alarm Indicator

Note: 1. As soon as the cause of an alarm is removed, the alarm is

reset automatically.

2. If multiple alarms occur simultaneously, the one with the

highest priority is displayed.

3. If the mode is changed to Adjust or Set Mode while an alarm

is in effect, the alarm output is reset and the ALM and SSR

indicators turn OFF.

4. If an SSR operation gate current level is set for a model with

phase control or cycle control, alarms will not be output for

SSR short circuits.

Processing Value Display Ranges and Functions

*1. The decimal point position depends on the input type.

K8AC-H21@@: 0.100 to 2.300

K8AC-H22@@: 1.00 to 23.00

K8AC-H23@@: 10.0 to 210.0

*2. If the display is below 0100, the bar display “----” will be shown.

Operation indicators

Maindisplayarea

Shift key

Up key

Down key Mode key

Level key

K8AC-H2@@@-FLK

Name Operation

Main display Displays processing values, parameter characters,

and set values.

Oper-

ation

indi-

cators

RUN (Mea-

surement

operation)

Lights when the power is turned ON and the

measurement operation is in progress.

OFF at all other times.

ADJ

(Adjust)

Lights while in Adjust Mode.

Flashes while in Test Mode.

OFF at all other times.

SET (Set) Lights while in Set Mode.

OFF at all other times.

GATE

(Gate)

Lights or turns OFF according to gate input status.

Gate pulse:

Lights for high voltage pulse; OFF for low

voltage pulse.

Gate signal (4 to 20 mA):

Lights for 4 mA or over; OFF for less than 4 mA.

SSR

(SSR error)

Lights when an SSR error occurs (open or short

circuit).

OFF when SSR is normal.

ALM

(Alarm) *Lights for heater burnout or overcurrent.

OFF at all other times.

Up key Increments a set value when the set value is in

change status.

Down key Decrements a set value when the set value is in

change status.

Shift key

Used to check set values while parameters are

displayed, and to put set values in change status.

Used to shift the set value digit when the set value is

in change status.

Mode key Used to switch the displayed parameter.

Level key Used to change the level.

Order

priority

Alarm

7-segment

display

characters

LED

indicator Alarm contents

1 Heater burnout 1 hbt1 ALM

indicator lit

CT1 heater

burnout detected.

2 Heater burnout 2 hbt2 ALM

indicator lit

CT2 heater

burnout detected.

3 SSR open circuit ssro SSR

indicator lit

SSR open circuit

detected (when

heater current

cannot be

detected with

temperature

control gate

output ON).

4 SSR short circuit ssrs SSR

indicator lit

SSR short circuit

detected (when

heater current is

detected with

temperature

control gate

output OFF).

5Heater layer

short circuit 1 hrs1 ALM

indicator lit

CT1 overcurrent

detected.

6Heater layer

short circuit 2 hrs2 ALM

indicator lit

CT2 overcurrent

detected.

Processing

value name

Display

characters

Display

range Unit Function

Heater 1

current ct 1

0100 to

2300

This is the CT1 heater

current processing value.

Alarm operations such as

the heater burnout alarm

are determined based on

this processing value.

Heater 2

current ct 2

0100 to

2300

This is the CT2 heater

current processing value.

Alarm operations such as

the heater burnout alarm

are determined based on

this processing value.

K8AC-H

Settings Method

Settings Methods for SSR and Contactor Control Heaters

Settings Conditions

Detecting burnouts in just one heater when ten 300-W rated heaters

are connected in parallel to a single-phase 200-V power supply.

The heater is SSR controlled.

Normal Heater Current and Heater Current with One

Heater Element Burnout

Normal current = (300 W × 10 (heaters))/200 V = 15.0 A

Current with one burnout = 15 A × 0.9 = 13.5 A

Heater burnout alarm set value =

Selecting Heater Element Burnout Detector Models

For the above example, K8AC-H22C@-FLK would be selected.

The burnout alarm set value is 14.3 A, so the current input range 2.00

to 22.00 A should be selected.

SSR control is used, so type C should be selected. (Type C is also

selected for Contactor control.)

Select the appropriate relay or transistor output specifications,

depending on the application.

K8AC-H Parameter Setting Procedure

(Only the minimum settings are shown here. Refer to pages 16 to

18 for information on how to set parameters.)

1. Turn ON the power to the K8AC-H. The initial status when power

is turned ON is called Run Mode.

2. Press the L Key for at least 3 s to change from Run Mode to

Adjust Mode (the mode for adjusting burnout alarm set values.)

3. Set the burnout alarm set values. (AL-1 = CT1 burnout alarm set

value and AL-2 = CT2 burnout alarm set value.)

Set “14.25” to AL-1.

Set the AL-2 burnout alarm set value to “----” so that it will not

detect heater burnout, because this is a single-phase heater.

4. Change to Run Mode.

Press the L Key while in Adjust Mode for at least 1 s to change

to Run Mode.

5. Check operation.

Test heater burnout detection by burning out one heater.

Also check that there are no malfunctions during temperature

control.

Note: The default setting for functions including the voltage

fluctuation compensation function, alarm hysteresis, output

ON-delay time, and SSR error detection function is OFF. Turn

ON any of these functions as required.

Settings Method for Cyclic and Phase Control Heaters

Settings Conditions

Detecting burnouts in one heater when five 1,000 W-rated heaters are

connected to each phase of a three-phase delta-connected 200-V

power supply.

A power regulator (Cyclic and Phase Control) performs heater

control.

Normal Heater Current and Heater Current With One

Heater Element Burnout

Example: When One of Five Single-phase Heaters (R-S) Burns

Out

Normal current = (1,000 W × 5 (heaters))/200 V = 43.3 A

Current with one burnout = 43.3 A × 0.91 = 39.4 A

(Refer to Rate of Change for Currents with Parallel Heaters on

page 10.)

Heater burnout alarm set value =

Selecting Heater Element Burnout Detector Models

For the above example, K8AC-H23P@-FLK would be selected.

The burnout alarm set value is 41.4 A, so the current input range 20.0

to 200.0 A should be selected.

Phase control is used, so type P should be selected. (Type P is also

selected for cyclic control.)

Select the appropriate relay or transistor output specifications,

depending on the application.

K8AC-H Parameter Settings Procedure

(Only the minimum settings are shown here. Refer to pages 16 to

18 for information on how to set parameters.)

1. Turn ON the power to the K8AC-H. The initial status when power

is turned ON is called Run Mode.

2. Press the L Key for at least 3 s to change from Run Mode to

Adjust Mode (the mode for adjusting burnout alarm set values.)

3. Change from Adjust Mode to Set Mode (the default settings mode

for all functions). The password “0169” is required to move to Set

Mode.

4. Set the heater control method parameter to PH-3 (three-phase

control).

The default setting is PH-1 (single-phase control).

Note: Set the parameter to CYCL (cyclic control) when using

cyclic control.

5. Press the L Key for at least 1 s to change from Set Mode to Adjust

Mode. Press the L Key again for at least 1 s to change from

Adjust Mode to Run Mode.

Note: The default setting for functions including the voltage

fluctuation compensation function, alarm hysteresis, output

ON-delay time, and SSR error detection function is OFF. Turn

ON any of these functions as required.

Burnout Alarm Set Value Setting Method

Setting Method

1. Wire the K8AC-H, temperature controller (4 to 20 mA current

output type), and power regulator (phase control).

2. Press the L Key on the K8AC-H for at least 3 s to change from

Run Mode to Adjust Mode.

3. AL-1 (CT1 burnout alarm set value) will be displayed when the

mode is changed to Adjust Mode. Press the S key once when AL-

1 is displayed. Next, press the U Key once. The present heater

current value will be displayed on the main display, so note this as

the normal current value. Always have the temperature controller

output at 20.0 mA at this time.

4. Next, disconnect one heater and note the heater current in this

burnout state. Alternatively, use the current when one heater is

burned out (calculated earlier) as the current during malfunction.

It is recommended that the current at an actual burnout is

confirmed.

5. Set the K8AC-H burnout alarm set value based on the results. The

burnout alarm set value is set at the mid-point between the normal

current and the current at malfunction, taking errors and variations

in heater capacity into consideration.

6. In this setting example, the set value for AL-2 (CT2 burnout alarm

setting) is the same as the set value for AL-1.

Note: 1. The K8AC-H automatically adjusts burnout alarm levels to

compensate based on the temperature controller current

output. The burnout alarm value must be set when the

temperature controller output is at 100% (20 mA), so be

sure to have the temperature controller at 20 mA output.

2. If the heater capacity is unbalanced, the burnout alarm

values for CT1 and CT2 may not be the same.

3. When using the power controller's gradient settings, change

the operation gate current level so that the heater current

value is within the measurement range. This parameter is

set by Gate Mode.

(Normal current + current at malfunction) =15.0 + 13.5 = 14.3 A

Normal current + current at malfunction =43.3 + 39.4 =41.4 A

K8AC-H

Measurement Monitor Value Display Ranges and Functions

Other than measuring the heater current, the K8AC-H can measure the power supply voltage, maximum/minimum current, maximum/minimum

voltage, and other values. The measurement data can be monitored from a host using RS-485 communications. The measurement monitor value

names, display ranges, and functions are given in the following table.

*Each measurement value can be individually reset. Refer to the K8AC-H Digital Heater Element Burnout Detector User’s Manual (Cat. No. N132)

for operating procedures.

Modes

Groups of setting items are called “modes.” The K8AC-H has five modes.

Note: If more than five minutes elapses with no operations performed in the Protection Settings Mode, Adjust Mode, or Set Mode, the status will

return automatically to the processing value display. If this occurs while settings are in progress, it may cause unintended operations in the

processing value display. Be careful not to allow this to happen.

Settings Data Notation

The letters of the alphabet in settings data are displayed as shown below.

Measurement monitor

value name

Display char-

acters Display range Unit Function

Power supply voltage sce 0085 to 0264 V

This is the measurement value of the K8AC-H power supply voltage. When the voltage

fluctuation compensation function is enabled, the heater burnout determination based on

this voltage is automatically compensated.

Heater 1 maximum current

*max1 0100 to 2300 A

These hold the maximum and minimum values for each processing value.

•The maximum and minimum heater currents after the power is turned ON or after a

maximum or minimum reset are displayed.

•The values are not saved when power is interrupted.

•The current values are not refreshed when startup lock is in effect and when the gate

input is enabled but the gate input is OFF.

•Measurement values for power supply voltages are always refreshed.

Heater 1 minimum current

*min1 0100 to 2300 A

Heater 2 maximum current

*max2 0100 to 2300 A

Heater 2 minimum current

*min2 0100 to 2300 A

Maximum power supply

voltage *maxs 0085 to 0264 V

Minimum power supply

voltage *mins 0085 to 0264 V

Number of alarm outputs acnt 0000 to 9999 Outputs

This value counts the total number of alarms output for heater burnout, SSR open and

short circuits, and heater layer shorts.

•The count is refreshed each time an alarm is output, and it is saved in non-volatile

memory.

•The value is saved when power is interrupted.

•The number of outputs is not counted for the test function.

•After counting to 9999, the value is held at 9999 and any further alarms are not

counted. To return the count to 0, perform a reset.

Processing value for alarm

output memo 0100 to 2300 A

This holds the CT1 or CT2 processing value when a heater burnout alarm is output.

•This is the most recent processing value, and it is refreshed each time a heater

burnout alarm occurs.

•The value is not saved when power is interrupted.

Run time otim 0000 to 9999 × 10h

This is the total run time value from when power is turned ON or the processing value is

reset until an alarm occurs.

•The total time is recorded in non-volatile memory approximately once per hour. If

power is interrupted within the hour, however, the data since the beginning of the hour

is lost and the total starts over from when the time was last saved.

•The total is stopped during heater burnout alarm output. When the alarm is cleared,

the total resumes from the time just before the alarm occurred.

Heater 1 input shift display

current isc1 −999 to 999 digit

This is the shift value for displaying the CT1 heater current measurement set in

measurement parameter CT1.

•The value is saved when power is interrupted.

Heater 2 input shift display

current isc2 −999 to 999 digit

This is the shift value for displaying the CT2 heater current measurement set in

measurement parameter CT2.

•The value is saved when power is interrupted.

Mode Function Alarm operation

Run Mode This is the normal operating mode, used for receiving inputs, executing heater burnout outputs, etc.

Operation goes into Run Mode immediately after power is turned ON. Executed

Adjust Mode This mode is used to change comparatively frequently set parameters, such as alarm value settings.

This also the mode for entering the password to move to the Set Mode. Stopped

Set Mode This mode is used to make the initial settings for the various functions. Stopped

Protection Settings

Mode

This mode is used to make settings to prevent unintended key operations. The protected modes are not displayed,

preventing changes to set values. Stopped

Test Mode This mode is used to simulate inputs with key operations to test alarm outputs. Executed

Gate Mode This mode sets the gate current value that stops an alarm or detection. Executed

ABCDEFGH I JKLMNOPQRSTUVWXYZ

abcdefghijklmnopqrstuVwxyz

K8AC-H

Operating Procedures

Moving between Modes

To Adjust Mode

When the L key is pressed for one second in Run Mode, the 7-

segment display will begin to flash. If the key is held down for another

two seconds, the mode will be switched to Adjust Mode.

To return to Run Mode from Adjust Mode, press the L key for at least

one second.

To Protection Settings Mode

When the L and M keys are pressed for one second in Run Mode,

the 7-segment display will begin to flash. If the keys are held down for

another five seconds, the mode will be switched to Protection Settings

Mode. To return to Run Mode from Protection Settings Mode, press

L and M keys for at least one second.

To Gate Mode

When the D key is pressed for at least one second in Run Mode, the

mode will be switched to Gate Mode. To return to Run Mode from

Gate Mode, press the D key for at least one second.

To Test Mode

When the S key is pressed for at least one second in Run Mode, the

mode will be switched to Test Mode. To return to Run Mode from Test

Mode, press the S key for at least one second.

To Set Mode (Password Input)

A special operation is required to move to the Set Mode.

Use the following procedure.

Setting the Parameter

The value set for each parameter is called the “set value.” Set values

include both numbers and characters.

The status when a set value is displayed is called “monitor status,”

and when it can be changed it is called “change status.”

Use the following procedure to display and change set values.

Procedure

1234

Hold down for at

least another 2 s.

Password: 0169

When the key

is released

Power ON

Run Mode Test Mode

Adjust Mode

Set Mode

Protection

Settings Mode Press the

L and M

keys for at

least 1 s.

Press the L

and M keys for

5 s.

Press the

L key for

at least 1s.

Press the L key

for at least 1 s.

Press the S

key for at least 1 s.

Press the L key

for at least 1s.

When the

key is

released

Press the S

key for at least 1 s.

Press the

L and M

keys.

Press the D

key for at least 1 s.

Press the D

key for at least 1 s. Gate Mode

init

Set Mode

Next parameter

in Adjust Mode

00000

0000

0169

amoV

MMM

SS 0169

When password

is incorrect

When password

is correct

Move to the Adjust Mode and use the M key to

display the parameter for moving to the Set Mode.

· The parameter characters are "amoV".

Press the S key to display the set value

(password).

Press the S key again to enable changing

the password.

Use U, D, and S keys to set the password.

The password is 0169.

· Press the M key.

· If the password is correct, the mode will change to

the Set Mode.

· If the password is incorrect, the next parameter will

be displayed while still in Adjust Mode.

Procedure

Monitor status Change status

To next parameter

Use the S, U, and

D keys to change

the set value.

2000 2000al-1

Press the S key while a parameter is displayed to

go into monitor status. The set value for that

parameter will be displayed.

If the set value is not to be changed, press the M

key while in monitor status to switch to the next

parameter.

Press the S key again while in monitor status to

enable the changing set value.

· The place where the set value can be changed will

begin to flash.

Press the M key to save the changed set value in

internal memory and switch to the next parameter.

· Changed set values will not be saved in memory if

the mode is changed by another key operation

without first pressing the M key.

Use the S, U, and D keys to change the set

value.

Note:

If a set value is out of

range, either too high or too

low, the maximum or

minimum value will

automatically be set. For

models with a current input

of 0.200 to 2.200 A, for

example, the maximum

value is 2.200 and the

minimum value is 0.200.

K8AC-H

Parameter List

The setting items in each mode are called “parameters.”

Parameters can be switched by using the M key.

Power supply voltage

measurement value

Voltage fluctuation

compensation standard value

Number of

CT passes 1

CT ratio 1

Number of

CT passes 2

CT ratio 2

Parameter Display

: Displayed for all models and settings.

: May not be displayed depending on the model or settings.

Setting change protection

*3*3

Voltage fluctuation

compensation standard value

Setting 1 for number of

effective digits to be displayed

after the decimal point

Setting 2 for number of

effective digits to be displayed

after the decimal point

init

sini

pini

hys1

hys2

gate

comp

stim

odly

soft

ssht

sopn

hrst

hral

msmd

dsel

psmd

pstm

dsmd

dsrf

u no

bps

len

sbit

nct1

ctr1

ndp1

nct2

ctr2

ndp2

prty

goht

al-1

al-2

ct 1

ct 2

sce

max1

min1

max2

min2

maxs

isc2

isc1

otim

memo

acnt

min5

1234

VfcV

amoV

aspt

wtpt

test

g-lV

sdly

sglV

cyct

Heater 1 current

Heater 2 current

Heater 1

maximum current

Heater 1

minimum current

Heater 2

maximum current

Heater 2

minimum current

Maximum power

supply voltage

(Processing value

display status)

Heater 2 input shift

display current

Heater 1 input shift

display current

Minimum power

supply voltage

Number of

alarm outputs

Processing value

for alarm output

RUN time

Password for

moving to Set

Mode: 0169

Burnout alarm

setting value 1

Heater layer short circuit

detection function

SSR open circuit

detection function

SSR short circuit

detection function

Output ON-delay time

Soft startup time

Startup lock time

Gate input function

Alarm hysteresis 2

Alarm hysteresis 1

Processing value

initialization

All initialization

Set value initialization

Heater control

method

Switchable

display

Power save

mode

Power save

mode standby

time

Display mode

Display

refresh time

Unit number

Baud rate

SSR ON delay

SSR operation

gate current level

Cycle time

Data length

Stop bits

Parity bit

Gate OFF

output hold time

Protection Mode Adjust Mode

Run Mode

Measurement

parameters

Set Mode

Setting change protection

1 s min.

3 s min.

Power ON

5 s min.

Burnout alarm

setting value 2

1 s min.

Test Mode

Gate Mode

1 s min.

An alarm is output if

the test value falls

below the burnout

alarm value 1 setting.

Alarm or detection is

stopped if the gate

current value falls

below the set value.

Note:

Displayed only for

the K8AC-H2@@@.

Heater layer short circuit

alarm set value

*1. Displayed when the Selectable Protection Level parameter is set to 0.

*2. Displayed by the K8AC-H2@P@-FLK.

*3. If more than five minutes elapses with no operations performed in Protection Settings Mode, Adjust Mode, Set Mode, or for a measurement

parameter, the status will return automatically to the processing value display.

If this occurs while settings are in progress, it may cause unintended operations to be performed in Run Mode (i.e., with measurement values

displayed). Be careful not to allow this to happen.

*4. Displayed by the K8AC-H2@C@-FLK.

K8AC-H

Parameter Defaults and Descriptions

Item

Mode Parameter name Description Param-

eter Setting range Default

Protec-

tion

Mode

Setting Change Protection

Restricts access to Adjust Mode or Set Mode from Run Mode.

0: Access enabled to both Adjust Mode and Set Mode.

1: Access enabled to Adjust Mode and disabled to Set Mode.

2: Access disabled to both Adjust Mode and Set Mode.

aspt 0 to 2 0

Setting Value Change

Prohibition Prohibits changes to set values. wtpt ON/OFF OFF

Adjust

Mode

Burnout Alarm

Value 1

K8AC-H@1Sets the output operation value for the burnout alarm.

The burnout alarm function can be disabled by setting the set value to

“−”.

al-1

0.200 to 2.200 A 1.000 A

K8AC-H@22.00 to 22.00 A 10.00 A

K8AC-H@320.0 to 200.0 A 100.0 A

Burnout Alarm

Value 2

K8AC-H@1Sets the output operation value for the burnout alarm.

The burnout alarm function can be disabled by setting the set value to

“−”.

al-2

0.200 to 2.200 A 1.000 A

K8AC-H@22.00 to 22.00 A 10.00A

K8AC-H@320.0 to 200.0 A 100.0 A

Voltage Fluctuation

Compensation Standard Value

Sets the standard voltage used by the voltage fluctuation

compensation function. The fluctuation compensation function

operates in respect to this set value.

vfcv 100 to 240 VAC 100 V

Set Mode

All Initialization Returns all set values and measurement values to their default

settings. init ON/OFF OFF

Set Value Initialization Returns all set values to their default settings. sini ON/OFF OFF

Processing Value Initialization Returns all measurement values to their default settings. pini ON/OFF OFF

Alarm Hysteresis 1 Sets hysteresis for the alarm output value for burnout detection

(undercurrent) and heater layer short circuits (overcurrent) for CT1. hys1 1 to 999 10

Alarm Hysteresis 2 Sets hysteresis for the alarm output value for burnout detection

(undercurrent) and heater layer short circuits (overcurrent) for CT2. hys2 1 to 999 10

Gate Input Function Turns the gate input function ON and OFF. If the gate input is turned

OFF, application as a simple ammeter is possible. gate ON/OFF ON

Voltage Fluctuation

Compensation Reference Value Turns the voltage fluctuation compensation function ON and OFF. comp ON/OFF OFF

Startup Lock Time Sets the lock time for the startup lock. stim 0 (OFF) to 255 s 0 (OFF)

Output ON-Delay Sets the output delay time. Set this parameter to set the operating time. odly 0.0 (OFF) to 99.9 s 0.0 (OFF)

Soft Startup Time Sets the soft startup time. Set this parameter only when using a soft

start function with the power regulator. soft 0.0 (OFF) to 99.9 s 0.0 (OFF)

SSR Short Circuit Detection Turns the SSR short circuit detection function ON and OFF. ssht ON/OFF OFF

SSR Open Circuit Detection Turns the SSR open circuit detection function ON and OFF. sopn ON/OFF OFF

Heater Layer Short Circuit

Detection (Overcurrent

Detection)

Turns the heater layer short circuit (overcurrent) detection function ON

and OFF. hrst ON/OFF OFF

Heater Layer Short

Circuit Alarm Level

(Overcurrent Alarm

Set Value)

K8AC-H@1 Sets the operating level for heater layer short circuit (overcurrent)

alarms.

The heater layer short circuit alarm level is the same for both CT1 and

CT2.

hral

0.200 to 2.200 A 2.000 A

K8AC-H@22.00 to 22.00 A 20.00 A

K8AC-H@320.0 to 200.0 A 200.0 A

Heater Control Method *1 Sets the control method of the cyclic/phase control heater. msmd PH1, PH3, CYCL PH1

Switchable Display Sets the CT for which to normally display the current. dsel CT1, CT2 CT1

Power Save Mode Turns entering the power save mode ON and OFF. psmd ON/OFF OFF

Power Save Mode Standby Time Sets the time to enter power save mode. pstm 10 to 300 s 60 s

Display Mode Sets a 7-segment (NORM). full-span comparison (CMP), or bar (BAR)

display. dsmd NORM, CMP, BAR NORM

Display Refresh Time Sets the refresh time for the display. dsrf 0.2 s, 0.5 s, 1.0 s, FAST 0.5 s

Unit Number Sets the unit number for RS-485 communications. u no 0 to 64 0

Baud Rate Sets the baud rate for RS-485 communications. dps 1200, 2400, 4800, 9600,

19200 9600

Data Length Sets the data length for RS-485 communications. len 7, 8 7

Stop Bits Sets the number of stop bits for RS-485 communications. sbit 1, 2 2

Parity Bit Sets the parity for RS-485 communications. prty EVEN, ODD, NONE EVEN

Gate OFF output hold time *2Sets the time from when the gate signal goes OFF until the burnout

alarm output turns OFF. goht 0 to 999 s 2 s

Number of CT passes 1 Sets the number of times the conductor for CT1 is passed through the

current transformer. nct1 1 to 99 times 1 time

CT Ratio 1 Sets the CT ratio for CT1. ctr1 1 to 999 1

Setting 1 for number of effective

digits to be displayed after the

decimal point

Sets the number of effective digits to be displayed after the decimal

point for the CT1 current display. ndp1 0 to 3 places

Depends

on the

model.

Number of CT passes 2 Sets the number of times the conductor for CT2 is passed through the

current transformer. nct2 1 to 99 times 1 time

CT Ratio 2 Sets the CT ratio for CT2. ctr2 1 to 999 1

Setting 2 for number of effective

digits to be displayed after the

decimal point.

Sets the number of effective digits to be displayed after the decimal

point for the CT2 current display. ndp2 0 to 3 places

Depends

on the

model.

Note: Shaded parameters must always be set regardless of the

measurement method.

K8AC-H

*1. Displayed by the K8AC-H2@P@-FLK.

*2. Displayed by the K8AC-H2@C@-FLK.

*3. You must restart the K8AC after you change the setting of the cycle time.

Dimensions (Unit: mm)

Digital Heater Element Burnout Detectors

Recommended Tools

Recommended Flat-blade Screwdriver

Manufacturer: Phoenix Contact

Model number: SZF0.4 × 2.5

Crimper for Bar Terminals (Crimping Tool)

Manufacturer: Phoenix Contact

Model number: CRIMPF0X UD6

Recommended power line diameters: AWG10 to AWG24

Recommended Crimp Terminals

Note: Securely tighten the terminal screws to the following torque:

Power supply terminals: 0.5 N·m

I/O terminals: 0.23 N·m

Item

Mode Parameter name Description Param-

eter Setting range Default

Set Mode

SSR ON delay Sets the SSR ON-delay time. sdly 0.0 (OFF) to 99.9 s 0.2 s

SSR operation gate current level

Sets the gate current level for SSR operation.

(This setting is valid only when cyclic or phase control is selected as

the heater control method.)

sglv 4.0 to 20 mA 7.0 mA

Cycle time *3

Sets the cycle time.

(This setting is valid only when cyclic control is selected as the heater

control method.)

cyct 0.2 to 3.0 s 0.2 s

Gate

Mode Gate Current Level *1 Sets the gate current value that stops an alarm, detection, or output. g-lv 7.0 to 20.0 mA 7.0 mA

35 2.1

1.7 4.5

100

K8AC-H2@@@-FLK

To remove a wire, insert the recom-

mended flat-blade screwdriver straight

into the hole under the push-in terminal

of the wire to enable easily remove it.

Terminals Recommended crimp terminals

Recom-

mended

wire gauge

1 and 2

M3 crimp terminals (Width: 5.8 mm max.)

AWG16 to

AWG18

3 to 14

M2 bar terminals: Al 0.34-8TQ (Phoenix Contact) AWG22

M2 bar terminals: Al 0.5-8WH (Phoenix Contact) AWG20

M2 bar terminals: Al 0.75-8GY (Phoenix Contact) AWG18

5.8 mm max.

K8AC-H

Optional Parts (Sold Separately)

10.5

0.5

21 2.5

2.8

5.5

5.8 dia.

1.2 dia.

Two, 3.5 dia.

Current Transformer

K8AC-CT20S

2.36 dia.

305

Two, M3

Depth: 4 max.

12 dia.

Current Transformer

K8AC-CT20L Accessories with K8AC-CT20L : Connection Example

Contact

Approx. 3 dia.

(22)

Approx. 6 dia.

Plug

Contact

Lead

Plug

100

Two, M3

Depth: 4 max.

12 dia.

Current Transformer

K8AC-CT200 (Pre-wired Leads)

urrent Transformer

K8AC-CT200L

1.8

4.1

5.9

5.2

Two, M5 screw holes

or two, 5.5-dia. holes

57 30 dia.

14.514.5

8.5

33.5

34.5

81.5

13.5

11 4.7

Four, M4 × 6 screws

9.3

1.7

9.3

Mounting Hole Dimensions

Note: Wire only the K and L terminals to the K8AC-H.

Leave the Kt and Lt terminals open.

K8AC-H

Safety Precautions

The following precautions are essential to ensure safety. Always heed

these precautions.

1. Do not use or store the Product in the following locations.

• Outdoors or in locations subject to direct sunlight, wind, or rain

• Locations subject to dust, metal powder, or corrosive gases (in

particular, sulfuric or ammonia gas)

• Locations subject to static electricity or noise

• Locations subject to flooding or exposure to oil

2. Use DIN Track for installation and mount the Product in the correct

direction.

3. Do not touch the terminals when power is being supplied. Electric

shock may occasionally occur.

4. Be sure you understand the contents of the Instruction Sheet and

User’s Manual and handle the Product according to the

instructions provided.

5. Check all terminal numbers and polarity when wiring and wire all

connections correctly.

6. Tighten terminal screws to the following torque.

Power supply terminals: 0.5 N·m

7. Use the Product within the specified temperature and humidity

ranges.

8. Do not use the product in locations subject to flammable or

explosive gases. Explosions may occasionally occur if the product

is used in such locations.

9. Do not install the Product in any way that would place a load on it.

10.Use the Current Transformer specified by OMRON.

11.Install an external switch or circuit breaker that complies with

applicable IEC60947-1 and IEC60947-3 requirements and label it

clearly so that the operator can quickly turn OFF the power.

12.The product must be handled by personnel who have knowledge

of electrical systems.

The following precautions are essential to ensure correct use. Always

heed these precautions.

1. Do not use the product in the following locations.

• Places subject to radiant heat from heat generating devices.

• Places subject to vibrations or physical shocks.

2. Make sure to use setting values appropriate for the controlled

object. Failure to do so can cause unintended operation, and may

result in accident or corruption of the product.

3. Do not use thinner or similar solvent for cleaning. Use commercial

alcohol.

4. When discarding, properly dispose of the product as industrial

waste.

5. To measure correct values, perform aging for approximately 15

minutes.

6. Only use this product within a board whose structure allows no

possibility for fire to escape.

Installation

1. When wiring, use only recommended crimp terminals.

2. Do not block areas around the product for proper dissipation of

heat. (If you do not secure space for heat dissipation, life cycle of

the product will be compromised.)

Mounting the K8AC-H

•Pull down the hook on the bottom of the K8AC-H, and then catch

the hook on the top of the K8AC-H onto the DIN Track and press

the K8AC-H onto the DIN Track until it locks into place.

Removing the K8AC-H

•Pull down on the hook with a flat-blade screwdriver and lift up on

the K8AC-H.

Noise Countermeasures

1. Do not install the product near devices generating strong high

frequency waves or surges.

2. When using a noise filter, check the voltage and current and install

it as close to the product as possible.

3. In order to prevent inductive noise, wire the lines connected to the

product separately from power lines carrying high voltages or

currents. Do not wire in parallel with or on the same cable as power

lines.

Other measures for reducing noise include running lines along

separate ducts and using shield lines.

Wiring

•Do not touch terminals or perform wiring while power is supplied to

the product. Doing so may result in injury or malfunction.

•Wire to the correct terminal number. Incorrect wiring may result in

damage to or burning of components.

Wiring the Push-in Terminals

•Directly insert the ferrule in the hole of the terminal to be wired.

Removing Wires from the Push-in Terminals

•Insert the recommended flat-blade screwdriver straight into the

hole to pull out the wire.

Precautions for Safe Use

Precautions for Correct Use

7 8 9 10 11 12 13 14

RUN ADJ SET GATE SSR ALM

7 8 9 10 11 12 13 14

K8AC-H

Why does the current measured by the K8AC-H decrease

during cyclic or phase control?

To enable measuring the current accurately for the heater

control value, the K8AC-H2@P@-FLK uses the current input

waveform from a gate input and the Current Transformer to

compensate the measured current value and burnout alarm

value. The compensated current value is displayed, so it

appears as if the measured current is lower during cyclic or

phase control, but the K8AC-H2@P@-FLK is operating

correctly.

How do I set the burnout detection alarm of the K8AC-

H2@P@-FLK when phase control is used?

Set the burnout alarm value of the K8AC-H2@P@-FLK based

on the current measurement value with the heater output at

100%. (This is because the burnout detection alarm of the

K8AC-H2@P@-FLK depends on the control input.)

When you set the burnout alarm value, make sure that you

make the setting based on the current measurement value

when the control of the power regulator is 100% or the rated

voltage is applied to the heater.

Q&A

Heater current

4 mA

Heater current

Heater burnout

alarm value

7 mA 20 mA

Control output from temperature controller

Heater Burnout Alarm Value

The heater burnout alarm value shifts

according to the control input (4 to

20 mA) from the temperature controller.

Warranty and Application Considerations

Warranty and Limitations of Liability

WARRANTY

OMRON's exclusive warranty is that the products are free from defects in materials and workmanship for a period of one year (or

other period if specified) from date of sale by OMRON.

OMRON MAKES NO WARRANTY OR REPRESENTATION, EXPRESS OR IMPLIED, REGARDING NON-INFRINGEMENT,

MERCHANTABILITY, OR FITNESS FOR PARTICULAR PURPOSE OF THE PRODUCTS. ANY BUYER OR USER

ACKNOWLEDGES THAT THE BUYER OR USER ALONE HAS DETERMINED THAT THE PRODUCTS WILL SUITABLY MEET

THE REQUIREMENTS OF THEIR INTENDED USE. OMRON DISCLAIMS ALL OTHER WARRANTIES, EXPRESS OR

IMPLIED.

LIMITATIONS OF LIABILITY

OMRON SHALL NOT BE RESPONSIBLE FOR SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES, LOSS OF PROFITS,

OR COMMERCIAL LOSS IN ANY WAY CONNECTED WITH THE PRODUCTS, WHETHER SUCH CLAIM IS BASED ON

CONTRACT, WARRANTY, NEGLIGENCE, OR STRICT LIABILITY.

In no event shall the responsibility of OMRON for any act exceed the individual price of the product on which liability is asserted.

IN NO EVENT SHALL OMRON BE RESPONSIBLE FOR WARRANTY, REPAIR, OR OTHER CLAIMS REGARDING THE

PRODUCTS UNLESS OMRON'S ANALYSIS CONFIRMS THAT THE PRODUCTS WERE PROPERLY HANDLED, STORED,

INSTALLED, AND MAINTAINED AND NOT SUBJECT TO CONTAMINATION, ABUSE, MISUSE, OR INAPPROPRIATE

MODIFICATION OR REPAIR.

Application Considerations

SUITABILITY FOR USE

OMRON shall not be responsible for conformity with any standards, codes, or regulations that apply to the combination of

products in the customer's application or use of the products.

Take all necessary steps to determine the suitability of the product for the systems, machines, and equipment with which it will

be used.

Know and observe all prohibitions of use applicable to this product.

NEVER USE THE PRODUCTS FOR AN APPLICATION INVOLVING SERIOUS RISK TO LIFE OR PROPERTY WITHOUT

ENSURING THAT THE SYSTEM AS A WHOLE HAS BEEN DESIGNED TO ADDRESS THE RISKS, AND THAT THE OMRON

PRODUCTS ARE PROPERLY RATED AND INSTALLED FOR THE INTENDED USE WITHIN THE OVERALL EQUIPMENT OR

SYSTEM.

Disclaimers

CHANGE IN SPECIFICATIONS

Product specifications and accessories may be changed at any time based on improvements and other reasons. Consult with

your OMRON representative at any time to confirm actual specifications of purchased product.

DIMENSIONS AND WEIGHTS

Dimensions and weights are nominal and are not to be used for manufacturing purposes, even when tolerances are shown.