5-5
PVM-14L2/20L2
3. Overvoltage protection and over-current protection circuits
The +115 V power line of the main power regulator has the over-voltage protection and over-current
protection circuits in order to protect the power supply circuits and the loads in the case of abnormal load
and when the voltage-feedback system becomes defective.
When over-current occurs in the +115 V power line, the latch circuit consisting of Q611 and Q612 is
turned on. When over-voltage occurs in the +115 V power line, the latch circuit consisting of Q609 and
Q610 is turned on. Then the drive pulse that is output from IC602 through the isolator PH602 is stopped
in order to stop operation of the main regulator.
This protection circuit is released in several minutes after the input power is turned off.
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