FAQ No. FAQ02150
What are the main causes of SSR failure and
what can be done about it?
Large Load Inrush Current:
Motors, lamps, and other loads with a large inrush current will cause the
output elements to be damaged if the inrush current resistance value of
the SSR is exceeded.
Consider using an SSR with larger capacity.
1. Counter-electromotive Force from Load :
Output elements may be damaged if there is a large counter-electromotive
force using valves, solenoids, and other inductive loads. Provide an
element that absorbs counter-electromotive force.
2. Failure due to External Surge:
External surges may cause sudden damage to input and output elements. Load
short circuit may also cause failure.
For safety, use a circuit that turns OFF the load if there is an
abnormality with the SSR by using a contactor or breaker installed on the
load power supply side. As a countermeasure against overcurrent, it is
recommended to add a quick-burning fuse in parallel with the load.
3. Installation Environments
Output elements may be damaged if the ambient operating temperature
exceeds the specified value. Take heat dissipation into account when
installing the SSR, such as by not obstructing the airflow to the heat
sinks. The SSR may be damaged by heat generated when the power is ON if
the screws are not tightened sufficiently or the SSR is used with
incomplete soldering. Wire and solder correctly.
Other Solid-state Relay
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