In a case where a load current flows in an energized state where a power supply is connected to a load, it is assumed that a measured voltage fluctuates due to a voltage drop caused by contact resistance of a relay contact, and thus the relay state cannot be accurately diagnosed. A relay control device that controls a relay connected between a secondary battery and a load device calculates, in a failure diagnosis during energization with the relay being closed, a contact resistance value of the relay based on a voltage applied to the relay and a current flowing through the secondary battery, and determines a first threshold set as a variable value in accordance with a temperature change amount of the relay and compares the calculated contact resistance value with the first threshold to diagnose a failure of the relay.

A load control device (e.g., a switching device) for controlling power delivered from an AC power source to an electrical device (e.g., a lighting load) may be configured to detect that a relay is stuck closed and attempt to fix the relay. The relay of the load control device may be adapted to be coupled between the source and the electrical device to control the power delivered to the electrical device so as to generate a switched-hot voltage. The load control device may comprise a detect circuit configured to generate a detect signal indicating a magnitude of the switched-hot voltage, and a control circuit configured to monitor the detect signal. The control circuit may be configured to determine that the relay is stuck closed in response to the detect signal, and to control the relay in order to attempt to fix the relay by repeatedly closing and opening the relay.

The disclosure relates to a circuit breaker with a monitoring device having an electronic switch and a mechanical changeover switch, where the mechanical changeover switch has a first terminal, a second terminal and a third terminal, where in a neutral position of the mechanical changeover switch the first terminal is connected to the third terminal and where in an operating position of the mechanical changeover switch the second terminal is connected to the third terminal, where the electronic switch is connected to the third terminal of the mechanical changeover switch as a series circuit, where when switching on the circuit breaker in a first switching state, initially the electronic switch is activated, where a measurement is taken at the first terminal using the monitoring device to determine whether essentially the same potential is present at the first terminal as at the third terminal and, it this is the case, the electronic switch is activated and the mechanical changeover switch is in an operating position in a subsequent additional switching state. Furthermore, the disclosure relates to methods for the circuit breaker.

A non-transitory, computer-readable medium may include instructions executable by at least one processor in a computing device to cause the processor to perform operations that include transmitting, to a first power source, a command to provide power to a coil of a switching device with a fixed current profile. The operations also include receiving one or more voltage measurements associated with the coil during a period of time, determining whether the voltage measurements associated with the coil indicate that one or more movable contacts of the switching device are at least partially welded to one or more contacts of an electric circuit, and transmitting an additional command to a second power source to disconnect a current to the coil in response to determining that the voltage measurements indicate that the movable contacts of the switching device are at least partially welded to the contacts of the electric circuit.

A power supply system includes a power source, a relay, a switch, and a controller. The relay is interposed between the power source and a load. The switch is configured to be coupled to the load in a state where the switch allows or disallows for power supply from the power source to the load when the relay is in a closed state. The controller is configured to control an operation of the switch. The controller is configured to execute forced driving control at a time of a closing operation of the relay. The forced driving control causes the switch to operate independently of a request for driving the load and thereby causes power to be supplied from the power source to the load.

A method of detecting welded contacts in a relay. The method includes performing, at a first point in time, the applying of a drive to the activation coil to conduct a coil current through the activation coil, the coil current increasing to a first current level, the first current level being less than a pull-in current of the relay; responsive to the coil current reaching the first current level, turning off the drive to the activation coil to discharge the coil current at a first clamping voltage; and measuring a first discharge time corresponding to a first inductance from the turning off of the drive to the activation coil to the coil current reaching a second current level, the second current level being less than the first current level. These operations are repeated at a second point in time to obtain a second inductance. Comparison of the first inductance and second inductance determines whether a difference between the first and second inductances exceeds a comparison criterion.

Power interface control device of a vehicle propulsion battery potential ports to carry out differential potential measurements, a current sensor to measure a current supplied by the propulsion battery and a closed container made of insulating material to which said ports and said sensor are associated, wherein said container comprises connection means to allow a mechanical coupling between the container and said electrical conductor.

A method of detecting welded contacts in a relay. The method includes performing, at a first point in time, the applying of a drive to the activation coil to conduct a coil current through the activation coil, the coil current increasing to a first current level, the first current level being less than a pull-in current of the relay; responsive to the coil current reaching the first current level, turning off the drive to the activation coil to discharge the coil current at a first clamping voltage; and measuring a first discharge time corresponding to a first inductance from the turning off of the drive to the activation coil to the coil current reaching a second current level, the second current level being less than the first current level. These operations are repeated at a second point in time to obtain a second inductance. Comparison of the first inductance and second inductance determines whether a difference between the first and second inductances exceeds a comparison criterion.

A load control device (e.g., a switching device) for controlling power delivered from an AC power source to an electrical device (e.g., a lighting load) may be configured to detect that a relay is stuck closed and attempt to fix the relay. The relay of the load control device may be adapted to be coupled between the source and the electrical device to control the power delivered to the electrical device so as to generate a switched-hot voltage. The load control device may comprise a detect circuit configured to generate a detect signal indicating a magnitude of the switched-hot voltage, and a control circuit configured to monitor the detect signal. The control circuit may be configured to determine that the relay is stuck closed in response to the detect signal, and to control the relay in order to attempt to fix the relay by repeatedly closing and opening the relay.

The disclosure relates to a circuit breaker with a monitoring device having an electronic switch and a mechanical changeover switch, where the mechanical changeover switch has a first terminal, a second terminal and a third terminal, where in a neutral position of the mechanical changeover switch the first terminal is connected to the third terminal and where in an operating position of the mechanical changeover switch the second terminal is connected to the third terminal, where the electronic switch is connected to the third terminal of the mechanical changeover switch as a series circuit, where when switching on the circuit breaker in a first switching state, initially the electronic switch is activated, where a measurement is taken at the first terminal using the monitoring device to determine whether essentially the same potential is present at the first terminal as at the third terminal and, it this is the case, the electronic switch is activated and the mechanical changeover switch is in an operating position in a subsequent additional switching state. Furthermore, the disclosure relates to methods for the circuit breaker.