A relay control circuit configured to control opening and closing of a contact of a non-latch relay, the non-latch relay including the contact and a coil configured to operate the contact, the relay control circuit comprises a high-voltage power supply; a low-voltage power supply; a power supply switching circuit; a first capacitor; and a reference voltage node, wherein the power supply switching circuit and one end of the first capacitor are connected to one end of the coil, the other end of the first capacitor and the reference voltage node are connected to the other end of the coil, and the power supply switching circuit is configured to switch a power supply connected to the one end. of the coil between the high-voltage power supply and the low-voltage power supply.

A safety switching apparatus for switching on or off a technical installation has a failsafe control/evaluation unit with an input for receiving an input signal. The failsafe control/evaluation unit is designed to process the input signal in order to produce an output signal for switching on or off the technical installation at a defined output signal time. The failsafe control/evaluation unit has a first output for transmitting the output signal to an electromechanical switch. The electromechanical switch has an operating contact for switching a load circuit of the technical installation and has a positively guided auxiliary contact in an auxiliary contact current path. The auxiliary contact can be used to carry a current for checking the switching position of the operating contact. A switching element is arranged in the auxiliary contact current path. The failsafe control/evaluation unit is designed to produce a switching signal at a defined switching signal time which has a time gap relative to the output signal time. The failsafe control/evaluation unit has a second output for transmitting the switching signal to the switching element in order to selectively allow or disallow the current through the auxiliary contact current path.

Systems and methods of detecting current leakage in a heating element are provided. An alternating current signal can be applied to the heating element. The heating element can have an associated line relay and an associated neutral relay coupled to a line terminal of the heating element and a neutral terminal of the heating element, respectively. A control system can be configured to control a sequence of operations of the line and neutral relays such that the magnitude of a leakage current flowing through the heating element to ground is increased. Such increased magnitude can facilitate detection of the leakage current. The detected leakage current can be compared with a leakage threshold. The control system can cease the operation of the heating element if the leakage current is greater than the leakage threshold.

A contactor assembly is provided for a battery module of an electric work vehicle comprising a battery management system. The battery module is configured to be charged and discharged via a first circuit. The first circuit comprises the contactor assembly, the contactor assembly comprising a first contactor in series with a second contactor. Each of the first contactor and the second contactor is configured to have a higher resistance to welding for a switching current flowing in a preferred direction than in a nonpreferred direction. The first contactor and the second contactor have opposite preferred directions. In response to an instruction to switch the contactor assembly, the battery management system is configured to determine whether the switching current direction is in the first direction or in the second direction, and to break or complete the first circuit with the contactor having a preferred direction in the switching current direction.

A charging device includes: a plurality of main relays forming a connection between an electric vehicle (EV)-side connector and an outlet-side connector; a relay welding sensing unit connected to the plurality of relays to sense the presence or absence of welding of the plurality of relays; a welding monitoring relay opening and closing between the relay welding sensing unit side node and a main relay side node; and a control unit controlling the open and close of the welding monitoring relay.

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.

A safety switching device for switching on and safely switching off an electrical load, comprising a failsafe evaluation/control unit, an output terminal for providing a potential, a switching element having a first working contact, wherein the potential is connectable to the output terminal via the first working contact, and an input terminal for receiving an input signal for operating the switching element via the evaluation/control unit. Additionally, the safety switching device comprises a separator having a connecting piece, a drive element and a separating element. The drive element is configured to mechanically move the separating element from a first position into a second position and the connecting piece and the first working contact electrically connect in series with one another the potential to the output terminal. Further, in the second position the separating element irreversibly separates the connecting piece into two pieces.

A protected switch includes first and second electromechanical relays with guided contacts, each including an electromagnet and electrical contacts. A first contact of the first relay and a first contact of the second relay are connected in series in order to form a switching circuit. The switch further includes an interconnection circuit which connects at least a portion of the other electrical contacts of the first and second relays. The excitation of the first electromagnet is conditional on the state of the second relay and the excitation of the second electromagnet is conditional on the state of the first relay.

A relay fault diagnosis device includes: at least one C-contact relay that has a common terminal, a normally open terminal and a normally closed terminal; a read-back circuit that is connected to the normally closed terminal of the relay; and a diagnostic section that outputs a test signal to the common terminal to diagnose a fault in the relay.

A relay arrangement includes at least two series-connected relays, which are mechanically and electrically connected to a main printed circuit board via first terminals and second terminals, and at least one flat conductor for conducting current between the at least two series connected relays. The flat conductor is mechanically connected to the main printed circuit board and electrically and thermally connected to the first terminals of the relays, and the at least one flat conductor is configured to dissipate heat produced during operation of the relays.