User`s manual

Power supply module specifications Specifications
MELSEC System Q, Hardware 12 – 55
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Overvoltage protection
The overvoltage protection device shuts off the 5 V DC circuit and stops the system if a voltage of 5.5 V DC is
applied to the circuit.
When this device is activated, the power supply module LED turns off. If this happens, switch the input power off,
then a few minutes later on. This causes the initial start for the system to take place.
The power supply module must be changed if the system is not booted and the LED remains off.
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If the momentary power failure time is within 20 ms, the system detects an AC down and suspends the operation
processing. However, the system continues operations after the power comes back.
If the momentary power failure time exceeds 20 ms, the system either continues or initially starts operations
depending on the power supply load. In case that the operation processing is continued, the system operates the
same as when the momentary power failure time is within 20 ms.
Supplying the same amount of AC to both the power supply module and the input module (such as QX10) can
prevent the sensor connected to the input module from being switched to the OFF status when the power supply
turns off.
Note, however, that if only the input module (such as QX10) is connected on the AC line, which is connected to
the power supply, an AC down detection in the power supply module may be delayed due to the internal capacitor
of the input module. To avoid this, connect a load of approx. 30 mA per input module on the AC line.