Patent ID: 11929223
Assignee: SEIKO EPSON CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 1:
2. An abnormality detection circuit comprising:
an AC power source coupled to a load via a first wiring line and a second wiring line;
a first relay contact disposed in a middle of the first wiring line;
a second relay contact disposed in a middle of the second wiring line;
a first comparative voltage detection circuit which is coupled to and located between the first wiring line extending from the first relay contact toward the AC power source and the second wiring line extending from the second relay contact toward the AC power source and to which a voltage is applied from the AC power source irrespective of whether the first relay contact and the second relay contact are open or closed;
a second comparative voltage detection circuit which is coupled to and located between the first wiring line extending from the first relay contact toward the AC power source and the second wiring line extending from the second relay contact toward the AC power source and to which a voltage is applied from the AC power source irrespective of whether the first relay contact and the second relay contact are open or closed;
a first voltage detection circuit which is coupled to and located between the first wiring line extending from the first relay contact toward the load and the second wiring line extending from the second relay contact toward the AC power source and to which the same voltage applied to the first comparative voltage detection circuit is applied when the first relay contact is closed, wherein the second wiring line extending from the second relay contact is connected to the AC power source while passing through no other switch;
a second voltage detection circuit which is coupled to and located between the first wiring line extending from the first relay contact toward the AC power source and the second wiring line extending from the second relay contact toward the load and to which the same voltage applied to the second comparative voltage detection circuit is applied when the second relay contact is closed, wherein the first wiring line extending from the first relay contact is connected to the AC power source while passing through no other switch; and
an abnormality detector that detects abnormalities of the first relay contact by comparing the voltage applied to the first comparative voltage detection circuit with the voltage applied to the first voltage detection circuit and detects abnormalities of the second relay contact by comparing the voltage applied to the second comparative voltage detection circuit with the voltage applied to the second voltage detection circuit.