© 2014 Littelfuse, Inc.

Specifications are subject to change without notice.

Revised: 07/11/14

Varistor Products

Radial Lead Varistors > ZA Series

Should transients occur in rapid succession, the average

power dissipation 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

Current Energy and Power Dissipation Ratings

Peak Pulse Current Test Waveform

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:

0

T = Time from 10% to 90% of Peak

T

T

Example - For an 8/20

µs Current Waveform:

8µs = T

20µs = T

100

90

80

70

60

50

40

30

20

10

0

-55

50

60

70

80

90

100110

120130 140150

FIGURE 1. CURRENT, ENERGY AND POWER DERATING

CURVE

Figure 1A - Power Derating for Epoxy Coated

Figure 2

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

100110 120130 140150

device. The operating values of a MOV need to be derated

at high temperatures as shown above. Because varistors

only dissipate a relatively small amount of average power

they are not suitable for repetitive applications that involve

substantial amounts of average power dissipation.

Figure 1B - Power Derating for Phenolic Coated

• Phenolic coated ZA Series devices are available with

improved maximum operating temperature of 125°C

• These devices also have improved temperature

cycling performance capability

• Ratings and specifications are as per standard

ZA Series except Hi–Pot Encapsulation

(Isolation Voltage Capability) = 500V

• To order: add 'X1347' to part number

(e.g. V22ZA3PX1347)

• These devices are not UL, CSA, VDE or CECC certified

• Contact factory for further details

• Product marking:

LF 9

P22P3

YYWW

Phenolic Coated

Option

Identifier

Lead-Free,

Halogen-Free

& RoHS Compliant

Indicator

Phenolic Coating Option -- ZA Series Varistors for Hi-

Temperature Operating Conditions:

Copper Electrode Option:

• Add 'W' to the end of the part

number (e.g. V240ZA05PW)

• Copper electrode option is only available

for V240~V750 for ZA series.

• Product marking:

LF 9

PZ240W

YYWW

Copper Electrode

Option

Identifier

Lead-Free,

Halogen-Free

& RoHS Compliant

Indicator