Varistor Products
High Energy Industrial
HA Varistor Series
Power Dissipation Ratings
PERCENT OF RATED VALUE
40
30
20
10
0
-55
50
60
70
80
90
100
110 120
130 140 150
AMBIENT TEMPERATURE (
o
C)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
PERCENT OF PEAK VALUE
100
90
50
O
1
= Virtual Origin of Wave
T = Time From 10% to 90% of Peak
T
1
= Virtual Front Time = 1.25 • t
T
2
= Virtual Time to Half Value (Impulse Duration)
Example: For an 8/20µs Current Waveform:
8µs = T
1
= Virtual Front Time
20µs = T
2
= Virtual Time to Half Value
T
T
1
T
2
TIME
10
O
1
FIGURE 2. PEAK PULSE CURRENT WAVEFORM
Transient V-I Characteristics Curves
10000
10000
Maximum Clamping Voltage
HA32 Series
110 to 750V AC Rating
V321CA32
V331CA32
V351CA32
Voltage (V)
V301CA32
TA = -55 C to 85C
V661HA32
V511CA32
V551CA32
V751CA32
V681CA32
V481CA32
Maximum Clamping Voltage
HA40 Series
110 to 750V AC Rating
TA = -55 C to 85C
V661
V751
V681
V571CA32
V441CA32
V421CA32
V421
V391
V441
V481
V511
V551
V571
Voltage
(V)
V391CA32
V351
1000
V331
V321
V301
1000
V271
V251
C111CA32
V131CA32
V151CA32
V271CA32
V251CA32
V201CA32
V181CA32
V141CA32
V201
V181
V131
V111
V141
V151
100
0.001
0.01
0.1
1
10
Current (A)
100
1000
10000
100000
100
0.001
0.01
0.1
1
10
Current (A)
100
1000
10000
100000
FIGURE 3. MAXIMUM CLAMPING VOLTAGE (V111HA32 - V751HA32)
FIGURE 4. MAXIMUM CLAMPING VOLTAGE (V111HA40 - V751HA40)
93
w w w. l i t t e l f u s e . c o m
VARISTOR
PRODUCTS
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 for average power dissipation.
100
90
80
70
60
50
2
LITTELFUSE [ LITTELFUSE ]
