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External warning circuit
The abnormality detection circuit, when activates, causes an external warning relay in the unit to acti-
vate. Major and minor failure relays are provided as the external warning relay.
Major failure relay
The abnormalities described below, when detected, forcibly stops operation and at the same time
causes a major failure relay in the unit to activate.
Detection of overcurrent
Temperature rise abnormality
Fuse disconnection
Thyristor open/short and load short to be detected by self-diagnosis function
Use the output of the major failure relay contact to monitor any abnormality.
The output of the major failure relay contact informs multiple abnormalities detected. So, check the indi-
cation of abnormality detection to know what abnormality was detected as a cause of activating the
relay.
Minor failure relay
The abnormalities listed below, when detected, causes a minor failure relay in the unit to activate.
Power supply undervoltage
Abnormal frequency
Load open to be detected by self-diagnostic function
Detection of heater disconnection (optional)
There may be the cases that power supply undervoltage and abnormal frequency are detected when
the control power supply is turned on/off. Therefore, the relay does not activate for about 3 seconds
after detection of such abnormalities even when they are actually detected.
Use the output of the minor failure relay contact to monitor any abnormality.
The output of the minor failure relay contact informs multiple abnormalities detected. So, check the indi-
cation of abnormality detection to know what abnormality was detected as a cause of activating the
relay.
Normal Between 1A and 1C Opened
Abnormality Between 1A and 1C Closed
Specifications for
relay contact
AC 250V 0.1A-1A
DC 30V 0.1A-1A
Normal Between HA and HC Opened
Abnormality Between HA and HC Closed
Specifications for
relay contact
AC250V 0.1A-1A
DC30V 0.1A-1A
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