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.

Contacts of a relay may glue together during operation. This state may be measured and a controller may issue a pulse width-modulated signal at a certain duty cycle and frequency in order to vibrate the relay contacts to make them open again. Once this is the case, the process is stopped. This process may be repeated a certain number of times, and if successfully degluing is not possible, a notification may be generated. Also after a certain number of degluing cycles, a signal may be generated to indicate replacement 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 invention relates to the diagnosis of the switching elements in a bidirectional DC-to-DC voltage converter. By charging a capacitor in the DC-to-DC voltage converter and then specifically actuating the switching elements and evaluating the voltage in the charged capacitor of the DC-to-DC converter, it is possible to identify a faulty switching element.

According to one aspect, embodiments of the invention provide a UPS system comprising an input, an output, a neutral connection, an AVR transformer, relays configured to selectively couple a primary winding of the AVR transformer to the input and the output, a bypass relay configured to selectively couple the primary winding to the neutral connection, a DC/AC inverter, and a controller configured to operate the relays, the bypass relay, and the DC/AC inverter to provide output AC power derived from at least one of input AC power and backup DC power, wherein in a backup power mode, the controller is further configured to operate the DC/AC inverter to convert the backup DC power into AC power provided to a secondary winding of the AVR transformer, to monitor the AC output power, and to identify that the bypass relay has decoupled the primary winding from the neutral connection.

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.

The objective of the present invention is to provide a relay-welding detection device and method, the device and method capable of determining, whether a relay is welded, by using an analog-digital converter (ADC). Another relay-welding detection device according to the present invention comprises: a first ADC for measuring a voltage of a relay input terminal; a second ADC for measuring a voltage of a relay output terminal; and a CPU for comparing the voltage of the relay input terminal with the voltage of the relay output terminal and determining whether the relay is welded.

A method for cleaning electrical contacts of an electrical switching device includes displacing a first electrical contact element and a second electrical contact element of an electrical contact relative to each other so that the first electrical contact element and the second electrical contact element are in a closed position; and when the first and second electrical contact elements are in the closed position applying a waveform on the electrical contact so that the first contact element and the second contact element are excited to undergo a mechanical vibration relative to each other.

Systems and methods are provided for releasing welded-shut contactors of a contactor system. An exemplary contactor system may include a contactor and a controller. The controller may be programmed to command a vibration across portions of the contactor as part of a weld release control strategy when the contactor is welded closed. The vibration may be achieved by repeatedly alternating between energizing and de-energizing a coil of the contactor in order to mechanically shock/vibrate a welded contact of the contactor.

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.