Pulse Withstanding Fusible
Flameproof Metal Film Resistors
EMC Series
• UL1412 recognised*
• Failsafe 240V mains fusing
• Good pulse handling capability
• Small size for power rating
• UL94-V0 flameproof protection
* Values 22R and above. UL file number E234469
Electrical Data
EMC2
Power rating at 70°CWatts 2
Resistance range Ohms 4R7 – 68R
TCR (25 to 75°C) ppm/°C100
Isolation Voltage Volts 500
Resistance Tolerance % 10, 20
Standard Values E12
Thermal Impedance °C/Watt 82
Ambient temperature range °C-55 to +155
Physical Data
Dimensions (mm) & Weight (g)
Type L max Dmax fmin dnom PCB mount centres Min bend radius Wt. nom
EMC2 10 4 27 0.8 18.4 1.2 0.55
Construction
The metal film is deposited onto a high purity ceramic rod. End caps are force fitted and termination wires are welded
to the end caps. Finally, a cement protection is applied to the resistor body prior to marking with indelible ink. The
cement protection is applied in a manner that leaves the terminations completely clear. This permits a well-defined
body length (clean lead to clean lead dimension L).
Terminations
Material: Solder-coated copper wire
Strength: The terminations meet the requirements of IEC 68.2.21
Solderability: The terminations meet the requirements of IEC 115-1 Clause 4.17.3.2
Solvent Resistance
The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits.
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own test data and is considered accurate at time of print.
Welwyn Components Limited
Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, England. Tel: 01670 822181 Fax: 01670 829465 Web: www.welwyn-tt.com
A subsidiary of TT electronics plc
L
f
D
d
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Flammability
The resistor coating is UL94-V0 rated and will not burn or emit incandescent particles under any condition of applied
temperature or power overload.
Marking
EMC resistors are colour coded with five bands. Four of the bands indicate value and tolerance in accordance with
IEC62. Parts with 20% tolerance have no fourth band. A fifth yellow band denotes constant voltage fusibility.
Performance Data
Maximum
Load at Rated Power: 1000hrs @ 70°C∆R% 5
Shelf life: 12 months at room temperature ∆R% 2
Derating from rated power at 70°C Zero at 155°C
Climatic ∆R% 3
Climatic Category 50/155/56
Temperature rapid change ∆R% 0.5
Resistance to solder heat ∆R% 0.5
Pulse Performance
Fusing Performance
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own test data and is considered accurate at time of print.
Welwyn Components Limited
Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, England. Tel: 01670 822181 Fax: 01670 829465 Web: www.welwyn-tt.com
Single Rectangular Pulse
1
10
100
1000
10000
0.01 0.1 1 10 100 1000 10000
Pulse Duration (ms)
Pk Power (W)
A subsidiary of TT electronics plc
IEC61000-4-5 1.2/50µ
s Pulse
0
100
200
300
400
500
600
700
0 10 20 30 40 50 60 70
Value (Ohms)
Pk Voltage (V)
EMC resistors fuse open circuit at overload powers
exceeding 60W within the time indicated on the
Fusing Characteristic. Their fusing performance at
lower overload powers is not specified.
EMC resistors fuse safely in the event of a 115Vrms /
240Vrms overload (line / mains short circuit
condition) without burning or emitting incandescent
particles.
After fusing, the resistance is at least 100 times
greater than the original nominal value.
Fusing Characteristic
(Constant Voltage)
0
5
10
15
20
40 50 60 70 80 90 100
Max. Fusing Time (s)
(4R7-8R2) (10R-68R)
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Application Notes
1. If the resistors are to dissipate full rated power, it is recommended that the terminations should not be soldered
closer than 4mm from the body.
2. Due to operating temperature limits imposed by some PCB materials, derating may be necessary. An estimate of
the temperature rise to be expected can be calculated using the thermal impedance figures given under Electrical
Data.
3. To protect against fire under all conditions of overload, a positive clearance of at least 13mm should be provided
between the body of the resistor and any combustible materials.
3. EMC resistors can also be supplied loose packed with radial, goalpost or lancet pre-formed leads, tape packed with
radial pre-formed leads, or in blister tape with Z-formed leads for SMD mounting. Consult factory for details.
Packaging
Our standard packaging for EMC is taped and boxed. The critical dimensions are shown in Figure 1. The component
wires will not protrude beyond the outside edge of the tapes. Alternative packaging is available by request.
mm
EMC2
B 68
C 5
Standard Quantities per Package
Type EMC2
Ammo pack 2000
Ordering Procedure
Specify type reference, value and tolerance as shown in this example of EMC2 at 33Ω, 20%:
EMC2 - 33R M
Type
Value (use IEC62 code)
Tolerance (use IEC 62 code)
K 10%
M 20%
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own test data and is considered accurate at time of print.
Welwyn Components Limited
Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, England. Tel: 01670 822181 Fax: 01670 829465 Web: www.welwyn-tt.com
Issue I 03/07/03 SJO
A subsidiary of TT electronics plc
b
f1 f2
Figure 1
Body location f1-f2 < 1.4mm
66
c
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IAmmo
Packaging
EMC2 2000/box Standard
I