Patent ID: 9202651
Filing Date: 2015-12-01
Classification: H01H

Abstract:
1. A unit for controlling one or more electromagnetic relays, each having a contact point and an exciting coil to which rated power is supplied so as to open and close the contact point, the unit comprising: a control circuit which carries out PWM control so as to keep an electromagnetic relay turned on, after turning on the electromagnetic relay by causing rated power to be supplied to an exciting coil of the electromagnetic relay; and a temperature detecting circuit that detects a resistance value of the exciting coil so as to allow the control circuit to calculate a temperature of the electromagnetic relay, wherein the control circuit changes, depending on external information, a controlling value in accordance with which the PWM control is carried out with respect to the electromagnetic relay, wherein the control circuit detects, from the temperature detecting circuit, a voltage corresponding to the resistance value of the exciting coil, wherein the control circuit calculates the temperature of the electromagnetic relay, and wherein the control circuit changes, depending on the temperature of the electromagnetic relay thus calculated, the controlling value in accordance with which the PWM control is carried out with respect to the electromagnetic relay.