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| V131DA40 Datasheet, PDF (3/4 Pages) Littelfuse – Varistor Products - High Energy Industrial | |||
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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.
100
90
80
70
60
50
40
30
20
10
0
-55 50 60 70 80 90 100 110 120 130 140 150
AMBIENTTEMPERATURE ( oC)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
100
90
50
10
O1
T
T1
T2
TIME
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
FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM
Transient V-I Characteristics Curve
6,000
5,000
4,000
3,000
MAXIMUM CLAMPING VOLTAGE
TA = -55oC to 85oC
DISC SIZE 40mm
130 TO 750 VM(AC) RATING
V751DA/DB40
V661DA/DB40
V511DA/DB40
V571DA/DB40
V481DA/DB40
2,000
V421DA/DB40
1,000
900
800
700
600
500
400
V151DA/DB40
300
V321DA/DB40
V271DA/DB40
V131DA/DB40
V251DA/DB40
200
10-2
10-1
100
101
102
103
104
105
PEAK AMPERES (A)
FIGURE 3. CLAMPING VOLTAGE FOR V131DA40, V131DB40 - V751DA40, V751DB40
88
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