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CA Varistor Series
The CA Series of transient surge suppressors are industrial high-energy
disc varistors (MOVs) intended for special applications requiring unique
electrical contact or packaging methods provided by the customer. The
electrode finish of these devices is solderable and can also be used with
pressure contacts. Discs of the same diameter may be stacked.
This series of industrial disc varistors are available in three diameter
sizes of 32, 40, and 60mm, with disc thicknesses ranging from 1.8mm
minimum to 32mm maximum. They offer a wide voltage range of from
250 to 2800 VM(AC)RMS .
For information on soldering considerations, refer to AN8820 update.
“Recommendations for Soldering Terminal Leads to MOV Varistor Discs”.
Features
• Provided In Disc Form For Unique Packaging By Customer
• Solderable Electrode Finish Options
• Pressure Contacts and/or Disc Stacking May be Utilized
• Standard Disc Sizes 32mm, 40mm, and 60mm Diameter
• Available Edge Passivation Insulation
• Wide Operating Voltage Range VM(AC)RMS 250V to 2800V
• High Peak Pulse Current Range . .........I
TM 20,000A to
70,000A
• Very High Energy Capability WTM ...............330J to 10,000J
• No Derating Up to 85oC Ambient
High Energy Industrial Disc
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High Energy Industrial Disc
CA Varistor Series
Absolute Maximum Ratings For ratings of individual members of a series, see Device Ratings and Specifications chart
Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 to 2800 V
DC Voltage Range (VM(DC)). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 to 3500 V
Transient:
Peak Pulse Current (ITM)
For 8/20µs Current Wave (See Figure 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20,000 to 70,000 A
Single Pulse Energy Range
For 2ms Current Square Wave (WTM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 to 10,000 J
Operating Ambient Temperature Range (TA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 to 85 OC
Storage Temperature Range (TSTG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 to 85 OC
Temperature Coefficient (αV) of Clamping Voltage (VC) at Specified Test Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <0.01 %OC
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device
at these or any other conditions above those indicated in the operational sections of this specification is not implied.
Device Ratings and Specifications
CA SERIES UNITS
MODEL
NUMBER
SIZE
MAXIMUM RATINGS (85oC) SPECIFICATIONS (25oC)
CONTINUOUS TRANSIENT
VARISTOR VOLTAGE AT
1mA DC TEST CURRENT
MAX
CLAMPING
VOLT VC AT
200A
CURRENT
(8/20µs)
TYPICAL
CAPACI-
TANCEVRMS V
DC
ENERGY
(2ms)
PEAK
CURRENT
(8/20µs)
VM(AC) VM(DC) WTM ITM MIN VN(DC) MAX VCf = 1MHz
(mm) (V) (V) (J) (A) (V) (V) (V) (V) (pF)
V131CA32 32 130 175 200 20000 184 200 228 350 4700
V151CA32 32 150 200 220 20000 212 240 268 410 4000
V251CA32
V251CA40
V251CA60
32
40
60
250 330 330
370
880
20000
40000
50000
354 390 429 680
650
620
2500
5000
10000
V271CA32
V271CA40
V271CA60
32
40
60
275 369 360
400
950
20000
40000
50000
389 430 473 750
730
680
2200
4500
9000
V321CA32
V321CA40
V321CA60
32
40
60
320 420 390
460
1100
20000
40000
50000
462 510 561 850
830
760
1900
3800
7500
V421CA32
V421CA40
V421CA60
32
40
60
420 560 400
600
1500
25000
40000
70000
610 680 748 1200
1130
1060
1500
3000
6000
V481CA32
V481CA40
V481CA60
32
40
60
480 640 450
650
1600
25000
40000
70000
670 750 825 1300
1240
1160
1300
2700
5500
V511CA32
V511CA40
V511CA60
32
40
60
510 675 500
700
1800
25000
40000
70000
735 820 910 1440
1350
1300
1200
2500
5000
V571CA32
V571CA40
V571CA60
32
40
60
575 730 550
770
2100
25000
40000
70000
805 910 1000 1600
1480
1420
1100
2200
4500
V661CA32
V661CA40
V661CA60
32
40
60
660 850 600
900
2300
25000
40000
70000
940 1050 1160 1820
1720
1640
1000
2000
4000
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CA Varistor Series
High Energy Industrial Disc
Power Dissipation Ratings
Should transients occur in rapid succession, the average power
dissipation result is the energy (watt-seconds) per pulse times the
number of pulses per second. The power so developed must be within
the specifications shown on the Device Ratings and Specifications table
for the specific device. Furthermore, the operating values need to be
derated at high temperatures as shown in Figure 1. Because varistors
can only dissipate a relatively small amount of average power they are,
therefore, not suitable for repetitive applications that involve substantial
amounts of average power dissipation.
V751CA32
V751CA40
V751CA60
32
40
60
750 970 700
1050
2600
25000
40000
70000
1080 1200 1320 2050
2000
1880
800
1800
3500
V881CA60 60 880 1150 3200 70000 1290 1500 1650 2340 2700
V112CA60
V142CA60
V172CA60
V202CA60
V242CA60
V282CA60
60
60
60
60
60
60
1100
1400
1700
2000
2400
2800
1400
1750
2150
2500
3000
3500
3800
5000
6000
7500
8600
10000
70000
70000
70000
70000
70000
70000
1620
2020
2500
2970
3510
4230
1800
2200
2700
3300
3900
4700
2060
2550
3030
3630
4290
5170
2940
3600
4300
5200
6200
7400
2200
1800
1500
1200
1000
800
NOTE: Average power dissipation of transients not exceed 1.5W, 2.0W and 2.5W for model 32mm, 40mm and 60mm, respectively.
MODEL
NUMBER
SIZE
MAXIMUM RATINGS (85oC) SPECIFICATIONS (25oC)
CONTINUOUS TRANSIENT
VARISTOR VOLTAGE AT
1mA DC TEST CURRENT
MAX
CLAMPING
VOLT VC AT
200A
CURRENT
(8/20µs)
TYPICAL
CAPACI-
TANCEVRMS V
DC
ENERGY
(2ms)
PEAK
CURRENT
(8/20µs)
VM(AC) VM(DC) WTM ITM MIN VN(DC) MAX VCf = 1MHz
(mm) (V) (V) (J) (A) (V) (V) (V) (V) (pF)
1. Peak current applies to applications rated up to 115V . Peak Current is 30kA for applications greater than 115V .
2. Peak current applies to applications rated up to 132V . Peak Current is 30kA for applications greater than 132V .
RMS
RMS
RMS
RMS
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
100
90
80
70
60
50
40
30
20
10
0
-55 50 60 70 80 90 100 110 120 130 140 150
AMBIENT TEMPERATURE ( oC)
PERCENT OF RATED VALUE
FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM
100
90
50
10
O1T
T1T2
TIME
PERCENT OF PEAK VALUE
O1 = Virtual Origin of Wave
T = Time From 10% to 90% of Peak
T1 = Virtual Front Time = 1.25 • t
T2 = Virtual Time to Half Value (Impulse Duration)
Example: For an 8/20µs Current Waveform:
8µs = T1 = Virtual Front Time
20µs = T2 = Virtual Time to Half Value
Device Ratings and Specifications (continued)
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High Energy Industrial Disc
CA Varistor Series
Transient V-I Characteristics Curves
FIGURE 3. CLAMPING VOLTAGE FOR V131CA32 - C751CA32 FIGURE 4. CLAMPING VOLTAGE FOR V131CA40 - V751CA40
FIGURE 5. CLAMPING VOLTAGE FOR V251CA60 - V881CA60 FIGURE 6. CLAMPING VOLTAGE FOR V112CA60 - V282CA60
200
6,000
5,000
4,000
3,000
2,000
1,000
900
800
600
400
300
10-3 10-2 10-1 100101102103104
MAXIMUM PEAK VOLTS (V)
PEAK AMPERES
V421CA32
V321CA32
V271CA32
V251CA32
105
500
700
MAXIMUM CLAMPING VOLTAGE
DISC SIZE 32mm
130 TO 750 VM(AC) RATING
V751CA32
V661CA32
V571CA32
V511CA32
V481CA32
TA = -55oC TO 85oC
V151CA32
V131CA32
200
6,000
5,000
4,000
3,000
2,000
1,000
900
800
700
600
500
400
300
10-2 10-1 100101102103104105
MAXIMUM CLAMPING VOLTAGE
DISC SIZE 40mm
130 TO 750 VM(AC) RATING
V421CA40
V151CA40
V751CA40
MAXIMUM PEAK VOLTS (V)
PEAK AMPERES
V131CA40
V321CA40
V271CA40
V251CA40
V511CA40
V481CA40 V571CA40
V661CA40
TA = -55oC TO 85oC
MAX CLAMPING VOLTAGE
DISC SIZE 60mm
250 TO 880VM(AC) RATING
TA = -55oC TO 85oC
6,000
5,000
4,000
3,000
2,000
1,000
900
800
700
600
500
400
300
200
10-2 10-1 100101102103104105
PEAK AMPERES (A)
V881CA60
V751CA60
V661CA60
V571CA60
MAXIMUM PEAK VOLTS (V)
V511CA60
V481CA60
V421CA60
V321CA60
V271CA60
V251CA60
30,000
20,000
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
10-2 10-1 100101102103104105
PEAK AMPERES (A)
MAX PEAK VOLTS (V)
V282CA60
V242CA60
V202CA60
V172CA60
V142CA60
V112CA60
MAX CLAMPING VOLTAGE
DISC SIZE 60mm
1100 TO 2800VM(AC) RATING
TA = -55oC TO 85oC
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CA Varistor Series
High Energy Industrial Disc
Pulse Rating Curves
FIGURE 7. SURGE CURRENT RATING CURVES FOR
V131CA32 - V321CA32
FIGURE 8. SURGE CURRENT RATING CURVES FOR
V421CA32 - V751CA32
FIGURE 9. SURGE CURRENT RATING CURVES FOR
V131CA40 - V751CA40
FIGURE 10. SURGE CURRENT RATING CURVES FOR
V251CA60 - V321CA60
FIGURE 11. SURGE CURRENT RATING CURVES FOR
V421CA60 - V282CA60
50,000
20,000
10,000
5,000
2,000
1,000
500
200
100
50
20
10
IMPULSE DURATION (µs)
20 100 1,000 10,000
SURGE CURRENT (A)
DISC SIZE 32mm
V131CA32 - V321CA32
1
2
10
102
105
106
INDEFINITE
104
103
12
10
102
INDEFINITE
106
105
50,000
20,000
10,000
5,000
2,000
1,000
500
200
100
50
20
10
IMPULSE DURATION (µs)
20 100 1,000 10,000
SURGE CURRENT (A)
DISC SIZE 32mm
V421CA32 - V751CA32
104
103
DISC SIZE 40mm
V131CA40 - V751CA40
50,000
20,000
10,000
5,000
2,000
1,000
500
200
100
50
20
10 20 100 1,000 10,000
SURGE CURRENT (A)
IMPULSE DURATION (µs)
106
10
2
1
INDEFINITE
104
103
102105
50,000
20,000
10,000
5,000
2,000
1,000
500
200
100
50
20
10
IMPULSE DURATION (µs)
1,000 10,000
10
102
103
INDEFINITE
106
20 100
2
DISC SIZE 60mm
V251CA60 - V321CA60
1
SURGE CURRENT (A)
105
104
100,000
50,000
20,000
10,000
5,000
2,000
1,000
500
200
100
50
20
10
20 100 1,000 10,000
IMPULSE DURATION (µs)
10
102
103
106
2
1DISC SIZE 60mm
V421CA60 - V282CA60
INDEFINITE
SURGE CURRENT (A)
104
105
NOTE: If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than ±10% could result. This type of shift, which normally results in a decrease of VN(DC),
may result in the device not meeting the original published specifications, but does not prevent the device from continuing to function, and to provide ample protection.
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High Energy Industrial Disc
CA Varistor Series
Series Dimensions
2.0
0.25
DIAMETER
(SEE TABLE)
PASSIVATION
COLLAR
ELECTRODE
THICKNESS
ELECTRODE
OPTIONAL
DISC DIAMETER
MODEL
SIZE
MILLIMETERS INCHES
MIN MAX MIN MAX
32 31.0 33.0 1.220 1.299
40 38.0 40.0 1.496 1.575
60 58.0 62.0 2.283 2.441
MODEL
VRMS
VM(AC)
THICKNESS (32mm DISC MODELS) THICKNESS (40mm AND 60mm DISC MODELS)
MILLIMETERS INCHES MILLIMETERS INCHES
MIN MAX MIN MAX MIN MAX MIN MAX
130†1.4 2.4 0.071 0.094 1.4 2.8 0.055 0.134
150†1.7 2.8 0.083 0.110 1.5 3.0 0.06 0.150
250 1.6 2.2 0.063 0.087 2.0 2.7 0.079 0.106
275 1.8 2.5 0.071 0.098 2.2 3.0 0.087 0.118
320 2.1 2.9 0.083 0.114 2.6 3.5 0.102 0.138
420 2.9 3.9 0.114 0.154 3.5 4.7 0.138 0.185
480 3.1 4.3 0.122 0.169 3.8 5.2 0.150 0.205
510 3.5 4.7 0.138 0.185 4.2 5.7 0.165 0.224
575 3.8 5.1 0.150 0.201 4.6 6.3 0.181 0.248
660 4.4 6.0 0.173 0.236 5.3 7.2 0.209 0.283
750 5.1 6.9 0.240 0.327 6.1 8.3 0.240 0.327
880†† ----7.310.30.2870.406
1100†† ----9.213.00.3620.512
1400†† ----11.516.00.4530.630
1700†† ----14.019.00.5510.748
2000†† ----17.022.50.6690.886
2400†† ----20.027.00.7871.063
2800†† ----24.032.00.9451.260
†Available in 32mm and 40mm only.
†† Available in 60mm size only.
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CA Varistor Series
High Energy Industrial Disc
Passivation Layer
The standard CA Series is supplied with passivation layer around the
outside perimeter of the disc forming an electrical insulator as detailed in
the dimensional drawing. The CA Series is also available without a
passivation layer for applications where the customer provides a suitable
encapsulation or potting material as recommended below.
(See Ordering Information.)
Encapsulated Recommendations
After lead attachment, the disc/lead assembly may be coated or
encapsulated in a package to provide electrical insulation and isolation
from environmental contamination as required by the application.
Coating/Filler materials for containers may include silicones,
polyurethanes, and some epoxy resins.Two examples of acceptable
polyurethanes are Dexter Hysol (US7013, parts A and B) and Rhenatech
(resin 4714, hardener 4900), or their equivalents. Materials containing
halogens, sulfides, or alkalines are not recommended.
Electrode Metallization
The standard CA Series is supplied with sintered silver electrodes on
CA32 devices and arc-sprayed copper-over-aluminum electrodes for CA40
and CA60 series. CA40 parts are also available with sintered silver elec-
trode, see “Ordering information.”In general, when discs are stacked to
attain a specific operating voltage or energy capability, the copper finish is
typically chosen. Likewise, the copper finish is used with high temperature
lead attach soldering operations (wave solder). The silver metallization is
typically used for solder reflow lead attach operations (I-R, Vapour-Phase).
The recommended temperature profile of a belt-fed convection oven is
shown in Figure 13.
Stacking and Contact Pressure
Recommendations
When applications require the stacking of Littelfuse CA discs or when
electrical connection is made by pressure contacts, the minimum pres-
sure applied to the disc electrode surface should be 2.2kGs (5 pounds).
The maximum recommended pressure applied to the disc electrode is
dependent upon diameter size and is given in the following table.
MODEL
NUMBER
SIZE
(mm)
TYPICAL DISC
WEIGHT (GRAMS)
V131CA32
V131CA40
32
40
9
21
V151CA32
V151CA40
32
40
11
23
V251CA32
V251CA40
V251CA60
32
40
60
8
17
39
V271CA32
V271CA40
V271CA60
32
40
60
10
18
42
V321CA32 32 11
V321CA40 40 22
V321CA60 60 50
V421CA32 32 15
V421CA40 40 28
V421CA60 60 66
V481CA32 32 16
V481CA40 40 31
V481CA60 60 71
V511CA32 32 18
V511CA40 40 35
V511CA60 60 80
V571CA32 32 20
V571CA40 40 38
V571CA60 60 88
V661CA32 32 23
V661CA40 40 44
V661CA60 60 101
V751CA32 32 26
V751CA40 40 51
V751CA60 60 116
V881CA60 60 141
V112CA60
V142CA60
V172CA60
V202CA60
V242CA60
V282CA60
60
60
60
60
60
60
178
220
265
317
377
450
TEMPERATURE (oC)
250
200
150
100
50
0
0 100 200 300 400 500 600 700 800 900
TIME (SEC)
FIGURE 13. TYPICAL BELT OVEN TEMPERATURE PROFILE
MODEL SIZE (mm) MAXIMUM PRESSURE
32 16N/CM2 (23LBs/IN2)
40 8N/CM2 (11.5LBs/IN2)
60 4N/CM2 (5.7LBs/IN2)
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CA Varistor Series
Ordering Information
The CA Series offers optional electrode finish materials and a glass
passivation edge option which must be designated. When ordering, the
code letters suffix as shown in the following table must be selected and
appended to the standard Model number.
NOTES:
1. The 60mm disc types V112CA60 to V282CA60, inclusive, are only
supplied with glass passivation and arc-sprayed copper finish
electrodes. (That is, with the “PC”option suffix code.)
2. The 32mm size discs are only available with silver metallization.
Note also that the CA Series receives no branding on the disc itself.
ELECTRODE
MATERIAL
NON-PASSIVATED
DISC
PASSIVATED
DISC
Arc-Sprayed Copper NC PC
Sintered Silver NS PS
Packaging and Shipping
The CA Series is supplied in bulk for shipment. Discs are packaged in
compartmentalized cartons to protect from scratching or edge-chipping
during shipment.
V251CA40PS
VARISTOR DESIGNATOR
MAX ACRMS WORKING VOLTAGE
(FIRST SIGNIFICANT DIGITS) VM(AC)
SILVER ELECTRODE
OPTION DESIGNATOR
DISC SIZE (mm) DIAMETER
SERIES DESIGNATOR
VM(AC) VOLTAGE DECADE MULTIPLIER
PASSIVATION OPTION DESIGNATOR
