Question
Solid-state Relays Output Open Circuit Malfunction: Why doesn’t the Solid-state Relays output turn ON?
Answer
The current-limiting resistor built into the Solid-state Relays may have experienced an open circuit error caused by application of overvoltage to the Solid-state Relays output terminal due to noise surge (including high frequency noise).
Solid-state Relays Internal Circuit with Problematic Section
Note:Depending on the Solid-state Relays, the I/O insulation element may be a photocoupler, and the load switching (output) element may be a thyristor.
Possible Causes:
1.A surge voltage was caused by the load power supply, or other loads connected to the load power supply line.
2.An inverter-controlled power supply was used (including high-frequency noise).
Reference Information Relating to Protection against External Noise
As protection against external noise, it is recommended that an overvoltage protection element (e.g., a varistor) be externally connected to the power supply line.
Connection Example 1
Connection Example 2
Note:Check the manufacturer's information for how to connect the overvoltage protection element.
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