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Varistor Products

High Energy Industrial

DA/DB Varistor Series

Power Dissipation Ratings

Should transients occur in rapid succession, the average power dissipa-

tion required is simply 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.

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

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

100

90

50

10

T

TIME

T = Time From 10% to 90% of Peak

Example: For an 8/20µs Current Waveform:

Transient V-I Characteristics Curve

FIGURE 3. CLAMPING VOLTAGE FOR V131DA40, V131DB40 - V751DA40, V751DB40

200

6,000

5,000

4,000

3,000

1,000

900

800

700

600

500

400

300

MAXIMUM CLAMPING VOLTAGE

DISC SIZE 40mm

130 TO 750 VM(AC) RATING

V421DA/DB40

V151DA/DB40

V751DA/DB40

PEAK AMPERES (A)

V131DA/DB40

V321DA/DB40

V271DA/DB40

V251DA/DB40

V511DA/DB40

V481DA/DB40

V571DA/DB40

V661DA/DB40

2,000