Provided is a relay unit that is inexpensive and has a long life, and a method for controlling a relay circuit. A series circuit of mechanical switches is connected in series to a load and a load power supply, and a control unit selects one of the mechanical switches as a selected switch, and performs a switching timing shift, which is constituted by at least one of a first operation in which the selected switch is switched to the closed state after the mechanical switch other than the selected switch, and a second operation in which the selected switch is switched to the open state prior to the mechanical switch other than the selected switch.

A circuit breaking system includes an output device for outputting an output signal; a control device controlled by the output signal; a power input terminal provided in the output device, for supplying power to the control device; a power supply to the output device, which has a ground terminal; a break circuit disposed between a power output terminal and the power input terminal; a switching circuit disposed between the break circuit and the power output terminal; and a short circuit disposed between a ground and a node which connects the power input terminal and the break circuit. The break circuit and the short circuit are operated so as to not be closed at the same time. When the switching circuit is closed, the break circuit is closed while the short circuit is open. When the switching circuit is open, the break circuit is open while the short circuit is closed.

A miniature and inexpensive relay device is provided. A relay device, i.e., a relay unit, includes a breakdown detection unit that does not detect breakdown of an operation of a first switching element and detect breakdown of an operation of a second switching element. When a switching control unit switches an external load circuit from non-conductivity to conductivity, the switching control unit switches the second switching element from non-conductivity to conductivity after switching the first switching element from non-conductivity to conductivity. When the switching control unit switches the load circuit from conductivity to non-conductivity, the switching control unit switches the first switching element from conductivity to non-conductivity after switching the second switching element from conductivity to non-conductivity.

For providing a very simple and reliable monitoring of the functionality of contacts together with a high flexibility of selection of the contacts a method for monitoring the functionality of redundantly interconnected contacts is provided, preferably within a load current circuit, wherein said n contacts, n=2, provide an electrical connection between a power supply and a load, wherein said n contacts are switchable by a controller and wherein each of said n contacts is designed for providing the electrical connection between the power supply and the load all alone. The method is characterized in that the controller switches on said n contacts during n subsequent activations according to a defined schedule according to which at the first of said n subsequent activations one of said n contacts is switched on first and the remaining n1 contacts are switched on afterwards, so that a verification regarding the functionality of said one of said n contacts is possible, and according to which at each of the n1 remaining subsequent activations a further one of said n contacts is switched on first with switching on of the remaining n1 contacts afterwards, so that after said n subsequent activations each of said n contacts has once been switched on first and a verification regarding the functionality of each of said n contacts is possible. Further, a corresponding method for subsequent deactivations and corresponding apparatuses are provided.

To enable an increase in a service life of a modular safety relay circuit, a modular safety relay circuit is provided for the safe switching on and/or off of at least one machine comprising at least one relay module to which the at least one machine is connected, wherein the relay module comprises at least two relay contacts that are connected in series and that can be brought from a first position into a second position and vice versa; and wherein one relay contact switches in advance by a delay of the other relay contact; and a control unit controlling the relay contacts that alternatingly controls the relay contacts in accordance with a state detection of the relay contacts with the delay.

A method of controlling positive and negative contactors in a high voltage electrical system includes sensing current flowing through each contactor prior to opening of the contactor and/or after closing of the contactor. A negative contactor weighted value is computed based at least partially on the sensed current flowing through the negative contactor during opening and/or closing. A positive contactor weighted value is computed based at least partially on the sensed current flowing through the positive contactor during opening and/or closing. The order of opening and/or closing of the contactors is determined utilizing at least one of the negative contactor weighted value and the positive contactor weighted value.

Provided is a relay unit that can sufficiently suppress defects that are caused by an insulation failure of insulating member that insulates and separates a load power supply from a device power supply, and a method for controlling a relay circuit. A control unit includes an insulating member diagnosis unit that performs diagnosis of an insulation failure of the capacitor.

A relay control circuit includes a relay module, a drive module, and a control module. The relay module comprises a plurality of relays and an auxiliary diagnostic unit electrically coupled to the relays. The drive module comprises a drive chip electrically coupled to the relays. The control module comprises a control unit electrically coupled to the drive chip and the auxiliary diagnostic unit. Each of the drive chip and the auxiliary diagnostic unit detects an operating state of each relay, and outputs the operating state of each relay to the control unit. When the operating state of each relay detected by the drive chip or the operating state of each relay detected by the auxiliary diagnostic unit indicates any relay fails, the control unit controls the drive chip to stop operating, and each relay is turned off.

The reliability of testing a normally closed contact in a relay unit may involve the following. Sending a first test signal to the first normally closed contact and detecting a return state of the first test signal sent, sending a second test signal different from the first test signal to the second normally closed contact and detecting a return state of the second test signal sent; and assessing an abnormality when at least one of the detection result for the return state of the first test signal does not satisfy a first predetermined criteria, and the detection result of the return state of the second test signal does not satisfy a second predetermined criteria different from the first predetermined criteria.

A safety circuit for fail-safe shutdown of a dangerous technical system with a plurality of disconnectable system component groups comprises a plurality of safety switching devices electrically connected to one another in series to form a closed-loop monitoring circuit in which electric monitoring current flows through the safety switching devices. Each of the safety switching devices includes: a fail-safe control unit that detects and evaluates information about a current operating state of any system component group assigned to it; and a current flow adjuster that changes the current flow within the monitoring circuit to interrupt the monitoring circuit in response to detection of a safety command by the safety switching device. The fail-safe control units generate a shutdown signal in response to an interruption of the current flow within the monitoring circuit, which causes the fail-safe shutdown of any of the system component group not already shut down.