Data Sheet
Panasonic Corporation Electromechanical Control Business Division
industrial.panasonic.com/ac/e/
Cautions for Use of Solid State Relays
Panasonic Corporation 2020
Protection Circuit
High-reliability SSR circuits require an adequate protection circuit, as
well as careful study of the characteristics and maximum ratings of the
device.
Over-Voltage Protection
The SSR load power supply requires adequate protection against
over-voltage errors from various causes. The methods of over-
voltage protection include the following:
1) Use devices with a guaranteed reverse surge withstand
voltage
(controlled avalanche devices, etc.)
2) Suppress transient spikes
Use a switching device in the secondary circuit of a transformer
or use a switch with a slow opening speed.
3) Use a surge absorption circuit
Use a CR surge absorber or varistor across the load power
supply or SSR.
Special care must be taken so power on/o surges or external
surges do not exceed the device’s rated load voltage. If a surge
voltage exceeding the device’s rated voltage is anticipated, use a
surge absorption device and circuit (e.g. a ZNR from Panasonic
Corporation).
Choosing the rated voltage of the ZNR
(1) Peak supply voltage
(2) Supply voltage variation
(3) Degradation of ZNR characteristic (1 mA
±10%)
(4) Tolerance of rated voltage (±10%)
For application to 100 V AC lines, choose a ZNR with the
following rated voltage:
(1) × (2) × (3) × (4) = (100 × √2) × 1.1 × 1.1 × 1.1 = 188 (V)
Example of ZNR (Panasonic)
Types
Varistor
voltage
Max. allowable
circuit voltage
Max.
control
voltage
Max.
average
pulse
electric
power
Withstanding
energy
Withstanding
surge current
Electrostatic
capacitance
(Reference)
(
10
/
1000
µ
s)
(
2
ms)
1
time
(
8
/
20
µ
s)
2
time
V
1
mA (V)
ACrms (V)
DC (V)
V
50
A (V)
(W) (J) (J) (A) (A)
@
1
KHz (pF)
ERZV
14
D
201
200
(
185
to
225
)
130 170 340 0
.
6
70
50 6
,
000 5
,
000 770
ERZV
14
D
221
220
(
198
to
242
)
140 180 360 0
.
6
78
55 6
,
000 5
,
000 740
ERZV
14
D
241
240
(
216
to
264
)
150 200 395 0
.
6
84
60 6
,
000 5
,
000 700
ERZV
14
D
271
270
(
247
to
303
)
175 225 455 0
.
6
99
70 6
,
000 5
,
000 640
ERZV
14
D
361
360
(
324
to
396
)
230 300 595 0
.
6
130
90 6
,
000 4
,
500 540
ERZV
14
D
391
390
(
351
to
429
)
250 320 650 0
.
6
140
100 6
,
000 4
,
500 500
ERZV
14
D
431
430
(
387
to
473
)
275 350 710 0
.
6
155
110 6
,
000 4
,
500 450
ERZV
14
D
471
470
(
423
to
517
)
300 385 775 0
.
6
175
125 6
,
000 4
,
500 400
ERZV
14
D
621
620
(
558
to
682
)
385 505 1
,
025 0
.
6
190
136 5
,
000 4
,
500 330
ERZV
14
D
681
680
(
612
to
748
)
420 560 1
,
120 0
.
6
190
136 5
,
000 4
,
500
320
W L
3 max
T
0.8 dia.
20 min
H
D
D
T
H
W
: 17.5 dia. max.
: 6.5 max.
: 20.5 max.
: 7.5 ±1
(Unit: mm)
Over-Current Protection
An SSR circuit operated without overcurrent protection may result in
damage to the device. Design the circuit so the device’s rated junction
temperature is not exceeded for a continuous overload current.
(e.g. Surge current into a motor or light bulb)
The surge-on current rating applies to over-current errors which occur
less than several tens of times during the service life of a
semiconductor device. A protection coordination device is required for
this rating.
Methods of over-current protection include the following:
1) Suppressing over-currents
Use a current limiting reactor in series with the load power supply.
2) Use a current shut-o device
Use a current limiting fuse or circuit breaker in series with the load
power supply.
Example of executing fuse selection of over-current protection
cooperation
NHR15 (fuse 15 A)
AQ-A (15 A type)
NHR10 (fuse 10 A)
No. of cycles at 60Hz
1
10
100
1,000
10 100 1,000
Fuse cut-off current
Surge ON current
(A peak)
ASCTB400E 202003
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