A safety switching device for the fail-safe disconnection of an external consumer has an internal consumer and switching elements for connecting in parallel the internal consumer with the external consumer. Read-back taps are arranged between the switching elements, a first and second pole of the external consumer, and the internal consumer. A signal processing unit includes a testing device and a memory, in which a first error pattern set is stored. The testing device is coupled to the read-back taps and executes a switching test having a minimum of three temporally-separated test intervals. In each test interval, the testing device receives a read-back signal from each read-back tap in order to generate a first test pattern. To identify a fault, the testing device matches the first test pattern with the first error pattern set.

A safety circuit coupled between a first direct current (DC) circuit and a second DC circuit, wherein the first DC circuit supplies power to the second DC circuit. The safety circuit comprises a first series connection between positive poles of the first and second DC circuits (the first series connection comprising a first diode, a second diode and a first controllable switch), a second series connection between negative poles of the first and second DC circuits (the second series connection comprising a third diode, a fourth diode and a second controllable switch), a first energy storage device (coupled between the positive pole of the second DC circuit and the first terminal of the second controllable switch), and a second energy storage device (coupled between the negative pole of the second DC circuit and the first terminal of the first controllable switch). The safety circuit further comprises a first feedback circuit for indicating an active state of the first controllable switch and a second feedback circuit for indicating an active state of the second controllable switch.

A switch control circuit and a switch control system includes a plurality of parallel-connected signal processing units. A first voltage signal and second voltage signal control turning-on and turning-off of the first controllable switch, and converting the first voltage signal into a third voltage signal; and the third voltage signal being connected with the first port of the controller; and the controller, configured to send a switch control instruction to a to-be-controlled terminal based on the third voltage signal. This circuit converts a electrical signal of a high voltage in strong electricity into a stable electrical signal of a low voltage in weak electricity, implements multiplex switch control in conjunction with the controller, and only processes voltage signals in the whole circuit, thereby avoiding processing signals of a plurality of types, and guaranteeing the reliability of the multiplex switch control.

A battery pack includes a main switch configured to electrically connect a battery module and a load, a power supply configured to supply driving power to the main switch, and a power blocking device configured to block the driving power based on a current flowing between the battery module and the load.

A safety switch device configured to perform at least one of connecting a load to a power supply and disconnecting the load from the power supply is provided. The safety switch device comprises a first set of two serially connected controllable switching elements; a safety circuit to verify a switching state of the first set of two switching elements, wherein each switching element of the first set of two switching elements is configured as a toggle; a control circuit configured to provide a test signal to the safety circuit; and decoupling means configured to galvanically decouple the load circuit from the control circuit. The decoupling means comprise a transformer, and the control circuit comprises a transformer driver configured to provide the test signal to the safety circuit via the transformer.

A controller 10 performs a first welding check and a second welding check in any order, and then performs a third welding check before a fourth welding check and also performs a fifth welding check before a sixth welding check. The first welding check is performed by turning on a first relay 18. The second welding check is performed by turning on a second relay 19. The third welding check is performed by turning on an in-phase relay, a third relay 20, and a fourth relay 21. The fourth welding check is performed by turning on an out-of-phase relay, the third relay 20, and the fourth relay 21. The fifth welding check is performed by turning on the in-phase relay, a fifth relay 22, and a sixth relay 23. The sixth welding check is performed by turning on the out-of-phase relay, the fifth relay 22, and the sixth relay 23.

An apparatus includes a circuit breaker having main contacts configured to be coupled within an electrical line. The circuit breaker also has trip contacts and auxiliary contacts. A protection relay is electrically coupled to the trip contacts of the circuit breaker and is configured to trip the circuit breaker. A trip circuit supervision relay has a first coil electrically coupled to the auxiliary contacts of the circuit breaker and a second coil electrically coupled to the trip contacts of the circuit breaker. The first coil and the second coil are magnetically coupled to each other. The trip circuit supervision relay is single circuit supervision relay that includes both first coil and the second coil and is configured to be magnetically operated by either of the first coil and the second coil.

To enable a safe monitoring with a small cabling effort of a modular safety relay circuit, a modular safety relay circuit for the safe control of at least one machine is provided comprising a safety relay unit that has at least one forcibly guided relay for the safe switching on and off of the machine and that generates output signals in dependence on input signals, wherein the input signals are provided by at least one connected signal transmitter and the output signals are communicated to the at least one machine; and at least one expansion relay unit for providing additional output connectors so that additional machines can be connected; wherein the expansion relay unit has at least one respective forcibly guided relay for the safe switching on and off of the machine and is monitored by means of a monitoring signal.

A power distribution system for a vehicle includes contactors that selectively electrically couple a charger to a high-voltage bus. The contactors are closed at the start of a charge event in an order that alternates for successive charge events. Upon completion of the charge event, the last closed contactor at the start of the charge event is opened first and a weld check is performed. If the weld check is indicative of a welded contactor, then the weld check is performed on the other contactor.

A validation device for a machinery safety system including a housing, an electrical processing circuit, at least one switch connected to the housing, at least one indicator, and a quick-connect interface for connecting in series to the machinery safety system. The electrical processing circuit is configured for inducing at least one fault in the machinery safety system, diagnosing the at least one fault, and indicating by the at least one indicator a status of the machinery safety system.