High Energy Industrial

BA/BB Varistor Series

Varistor Products

74

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Power Dissipation Ratings

Should transients occur in rapid succession, the average power dissipation

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 Characteristics 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.

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 8/20

µs Current Waveform:

8

20

FIGURE 3. STANDBY POWER DISSIPATION vs APPLIED

TYPICALTEMPERATURE COEFFICIENT

1.0

0.8

0.6

0.4

0.2

0.1

0.08

0.06

0.04

80

90

100

110

FIGURE 4. TYPICAL STABILITYOF STANDBY POWER

0.5

0.4

0.3

0.2

0.1

0

0

10

100

1,000

Typical Performance Curves

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