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

Claim 0:
1. 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 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, both ends of the first comparative voltage detection circuit being connected to the first and second wiring lines, respectively;
a second comparative voltage detection circuit 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, both ends of the second comparative voltage detection circuit being connected to the first and second wiring lines, respectively;
a first voltage detection circuit to which a voltage is applied from the AC power source when the first relay contact is closed, one end of the first voltage detection circuit being connected to the AC power source via the second wiring line while passing through no other switch;
a second voltage detection circuit to which a voltage is applied from the AC power source when the second relay contact is closed, one end of the second voltage detection circuit being connected to the AC power source via the first wiring line 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.