Datasheet

Solid State Relays Common Precautions
●Before Using SSR
1. The SSR in operation may cause an unexpected accident.
Therefore it is necessary to test the SSR under the variety of
conditions that are possible.
For example, as for the characteristics of the SSR, it is
necessary to consider differences in characteristics between
individual SSRs.
2. The ratings in this catalog are tested values in a temperature
range between 15°C and 30°C, a relative humidity range
between 25% and 85%, and an atmospheric pressure range
between 88 and 106 kPa. It will be necessary to provide the
above conditions as well as the load conditions if the user
wants to confirm the ratings of specific SSRs.
■Input Circuit
●Connecting to the Input Side
There is variation in the input impedance of SSRs. Therefore, do
not connect multiple inputs in series. Otherwise malfunction may
occur.
●Input Noise
SSRs need only a small amount of power to operate. This is why
the input terminals must shut out electrical noise as much as
possible. Noise applied to the input terminals may result in
malfunction. The following describes measures to be taken
against pulse noise and inductive noise.
1. Pulse Noise
A combination of capacitor and resistor can absorb pulse
noise effectively. The following is an example of a noise
absorption circuit with capacitor C and resistor R connected to
an SSR incorporating a photocoupler.
The value of R and C must be decided carefully. The value of
R must not be too large or the supply voltage (E) will not be
able to satisfy the required input voltage value. The larger the
value of C is, the longer the release time will be, due to the
time required for C to discharge electricity.
Note. For low-voltage models, sufficient voltage may not be applied to the
SSR because of the relationship between C, R, and the internal
impedance. When deciding on a value for R, check the input
impedance for the SSR.
2. Inductive Noise
Do not wire power lines alongside the input lines. Inductive
noise may cause the SSR to malfunction. If inductive noise is
imposed on the input terminals of the SSR, use the following
cables according to the type of inductive noise, and reduce the
noise level to less than the must release voltage of the SSR.
Twisted-pair wire: For electromagnetic noise
Shielded cable: For static noise
A filter consisting of a combination of capacitor and resistor will
effectively reduce noise generated from high-frequency
equipment.
●Input Conditions
1. Input Voltage Ripples
When there is a ripple in the input voltage, set the input
voltage so that the peak voltage is lower than the maximum
operating voltage and the root voltage is above the minimum
operating voltage.
2. Countermeasures for Leakage Current
When the SSR is powered by transistor output, the must
release voltage may be insufficient due to leakage current
while power is OFF. To counteract this, connect bleeder
resistance as shown in the diagram below and set the bleeder
resistance so that VR is half of the release voltage or less.
The bleeder resistance R can be obtained in the way shown
below.
E : Voltage applied at both ends of the bleeder resistance =
half of the release voltage of the SSR
I
L : Leakage current of the transistor
I : Release voltage of SSR
The actual value of the release current is not given in the
datasheet and so when calculating the value of the bleeder
resistance, use the following formula.
For SSRs with constant-current input circuits, calculation is
performed at 0.1 mA.
The calculation for the G3M-202P DC24 is shown below as an
example.
Precautions for Correct use
R
C
Pulse width
Pulse voltage
10
6
4
2
1
0.6
0.4
0.2
0.1
0.06
0.04
0.02
0.01
20 40 60 100 200 400 600 1000
Pulse voltage (V)
1000 Ω 1 μF
330 Ω 1 μF
1000 Ω 0.1 μF
330 Ω 0.1 μF
1000 Ω 0.01 μF
330 Ω 0.01 μF
330 Ω 0.001 μF
1000 Ω 0.001 μF
Pulse width (μs)
High-frequency
device
Filter
Note: R: 20 to 100 Ω
C: 0.01 to 1 μF
Load
Peak voltage
Root voltage
0 V
Bleeder resistance
R≤
E
I
L−I
Release current for SSR =
Minimum value of release voltage
Input impedance
Release current I=
1 V
1.6 kΩ
=0.625 mA
Bleeder resistance R=
1V×1/2
I
L−0.625 mA
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