26
Fig 2
V
C
V
B
V
S
I
T
’
I
L
t
a
t
b
I
P
I
P
V
C
I
P
/
2
V
S
:Stand-off voltage
V
B
:Break down voltage
V
C
:Maximum clamping voltage
I
L
:Maximum leakage current
I
T
:Test current
I
P
:Peak pulse current
I
T
L
1
L
2
1.5 max.
Paper
I
P
V
B
’
Fig 1
Fig 3
Fig 4
Fig 5
Fig 6
5 or 7
2 max.
1 max.
6
1 max.
6
52
L:26 or 52
Unit:(mm)
10
5
10
4
10
4
10
3
10
2
10
1
10
2
10
1
10
3
10
2
10
Time (ms)
P
Ambient temperature ( C)
Time
C
Time
Peak current
Test pulse waveform
Maximum clamping voltage
V
C
Z6 type
Z2 type
ZD, Z1 type
clamping voltage waveform
100
80
60
40
20
20
40
60
80
100
120
140
160
V
RD
suppressor used for protecting electric
circuits from surge voltage and thus
preventing breakdown.
VRD has superior surge suppression
characteristics, such as extremely fast
response time, very low clamping voltage,
and high surge capacity. Unlike metal oxide
varistors, VRD does not have characteristics
to change with surge variations within the
rated capacity. This feature comprises
another superior characteristics of the VRD
as a transient voltage suppressors.
Electrical characteristics
Figure 1 shows the electrical characteristics. Bipolar
type has almost symmetrical breakdown Voltage (V
B
)
The reverse breakdown voltage of the ZD type is 200
Volts or more at 10 A DC.
Surge capability
Allowable surge capability (Pm) is determined by the
following equation:
Pm Ip V
C
Ip:Peak current
Vc:Maximum clamping voltage
The allowable surge capability (peak pulse power) of
VRD is shown in following Figure 3 and the surge ca-
pability derating characteristics are shown in Figure 6.
Surge suppression characteristics
When EXP waveform is applied to the circuit
below, the surge suppression waveform shown in the
figure 5 can be observed.
Power derating
Surge waveform
There are many types of surge waveform depending
on the source of the surge. For the VRD surge
suppression characteristics test, the EXP waveform
shown below is used. The EXP waveform is shown as
ta
/
tb depending on the time width, however 10/1000
waveform is used as the standard test waveform.
Taping
One of standard taping is as shown in Figure.
L
1
L
2
Z1 type
Z2 type
Z6 type
ZS1 type