A switch system includes a system main relay, a temperature measuring unit, and a controller. The system main relay is configured to electrically connect a battery and an onboard device to each other by turning on a contact point, and to electrically disconnect the battery and the onboard device by turning off the contact point. The temperature measuring unit is configured to measure temperature of the contact point of the system main relay. The controller is configured to cause the system main relay to repeatedly turn on and off the contact point at a predetermined timing, (i) when the temperature of the contact point of the system main relay is a predetermined temperature or more or (ii) when an amount of rise in the temperature of the contact point is a predetermined amount or more.

The magnetic coil driving circuit of the magnetic contactor according to the present invention comprises a semiconductor switch configured to open or close a circuit for magnetizing or demagnetizing a magnetic coil; a pulse width modulation unit configured to output a pulse signal as a control signal for turning on or off the semiconductor switch; a control unit configured to output a control signal for changing a pulse width of the pulse signal to the pulse width modulation unit; and a temperature detection and protection unit configured to detect a temperature inside the magnetic contactor, output an output signal for turning off the semiconductor switch when the temperature exceeds an allowable temperature, and control the semiconductor switch by the pulse signal from the pulse width modulation unit when the temperature is within the allowable temperature.

Disclosed is a method for closing the contacts of an electrical switching device during a switch-on process, wherein for a fixed first time period, the first time period and the first voltage being selected in such a way that the armature is not set into motion during the first time period, or the first voltage is applied to the coil until a certain current value is reached, the first time period being the time period until said certain current value is reached, and the first voltage being selected in such a way that the armature is not set into motion during the first time period, wherein a suitable second voltage is defined, the second voltage being greater than the first voltage and being applied to the coil during a second time period in order to move the armature from the open position into the closed position.

A signal conditioning circuit for monitoring at least one parameter of an electrical signal in an electrical conductor. The signal conditioning circuit can include an integrator circuit having an input for receiving a signal from a current sensor coupled to the electrical conductor. A first analog switch has an input coupled to the output of the integrator circuit, wherein the first analog switch is controlled by the output of a time delay circuit. A power stage circuit has an input coupled to the output of the first analog switch. The signal conditioning circuit can be used for line fault detection.

The present invention relates to a relay protective device, a construction machine, a relay protection control method and apparatus, and a computer readable storage medium. The relay protective device includes: a power supply input contact; a relay protective module comprising a bistable relay and an output contact, wherein the bistable relay comprises a contact, a pull-in coil, and a release coil; an input terminal of the contact, an input terminal of the pull-in coil, and an input terminal of the release coil are connected to the power supply input contact; an output terminal of the contact is connected to the output contact; and a central control unit comprising a first port connected to the output contact, a second port connected to an output terminal of the pull-in coil, and a third port connected to an output terminal of the release coil; the central control unit is used for controlling the pull-in coil and the release coil to be alternately powered on so as to oscillate the contact when a voltage of the output contact is less than a first threshold and is not less than a second threshold, wherein the first threshold is less than a standard working voltage of the bistable relay, and the second threshold is the minimum allowable working voltage of the bistable relay.

With a power supply control device, if semiconductor switches of a switch circuit are on and a relay contact is off, a controller determines whether or not a switch electric current detected by an electric current sensor is at least a threshold. If the controller has determined that the switch electric current is at least the threshold, then an electric current supply unit switches on the relay contact, and a drive circuit switches off the semiconductor switches. The controller changes the above-described threshold in accordance with the length of the lapse of time from when an electric current flows through the switch circuit.

An electromagnetic relay deicing system includes an electromagnetic relay that includes a common terminal, a normally open terminal, and a normally closed terminal and that supplies electric power from an electric power supplier to an electrical apparatus when the common terminal and the normally open terminal are connected, and a control circuit that controls an on-state and an off-state of the electromagnetic relay. During the on-state of the electromagnetic relay, the common terminal and the normally open terminal are connected by a movable piece. During the off-state of the electromagnetic relay, the common terminal and the normally closed terminal are connected by the movable piece. The control circuit deices the electromagnetic relay by causing, during the off-state of the electromagnetic relay, electric conduction between the common terminal and the normally closed terminal connected by the movable piece so that ice on a surface of the normally open terminal melts.

With a power supply control device, if semiconductor switches of a switch circuit are on and a relay contact is off, a controller determines whether or not a switch electric current detected by an electric current sensor is at least a threshold. If the controller has determined that the switch electric current is at least the threshold, then an electric current supply unit switches on the relay contact, and a drive circuit switches off the semiconductor switches. The controller changes the above-described threshold in accordance with the length of the lapse of time from when an electric current flows through the switch circuit.

A switch system includes a system main relay, a temperature measuring unit, and a controller. The system main relay is configured to electrically connect a battery and an onboard device to each other by turning on a contact point, and to electrically disconnect the battery and the onboard device by turning off the contact point. The temperature measuring unit is configured to measure temperature of the contact point of the system main relay. The controller is configured to cause the system main relay to repeatedly turn on and off the contact point at a predetermined timing, (i) when the temperature of the contact point of the system main relay is a predetermined temperature or more or (ii) when an amount of rise in the temperature of the contact point is a predetermined amount or more.

An electromagnetic relay deicing system includes an electromagnetic relay that includes a common terminal, a normally open terminal, and a normally closed terminal and that supplies electric power from an electric power supplier to an electrical apparatus when the common terminal and the normally open terminal are connected, and a control circuit that controls an on-state and an off-state of the electromagnetic relay. During the on-state of the electromagnetic relay, the common terminal and the normally open terminal are connected by a movable piece. During the off-state of the electromagnetic relay, the common terminal and the normally closed terminal are connected by the movable piece. The control circuit deices the electromagnetic relay by causing, during the off-state of the electromagnetic relay, electric conduction between the common terminal and the normally closed terminal connected by the movable piece so that ice on a surface of the normally open terminal melts.