2-1
Publication 700-AT001A-EN-E June 2002
Chapter
2
Considerations When Designing SSR Control
Systems
Input Circuit
Input Noise
SSRs need only a small amount of input/control 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 describe measures to be taken against electrical pulse
noise and inductive noise.
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A combination of capacitor and resistor on the input/control circuit 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.
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
SSR’s required input must operate (ON) voltage value. The larger the
value of C, the longer the release time will be, due to the time required
for C to discharge electricity.
Pulse width
Pulse voltage
R
C
E
