Electrical circuits are started as well as cut off by valves built in electrical devices. Such components vary in the amount of current they can withstand. There are low versus strong power fuses. Notably, a high voltage contactor is widely used for controlling extremely great currents. Numerous devices use this and a few are discussed below.

Three elements work together to allow full functioning of fuses. These components are a coil, pole, and auxiliary. To start with, valves are switched on and off by coils. They are spiraled to reduce the distance traveled by signals, hence allow faster action. Poles transmit power signals to fuses. Finally, auxiliaries are used for paneling as well as indicating circuit application.

The first application point is in lighting control. Bigger lighting connections are done in offices, or merchandising buildings require connectors that can withstand great power. Such is sustained by these contacts. They are designed to have two working coils. One is temporarily energized to close connections in valves while the other is used to open switches. Latching strong current connectors are used to prevent a lot of power consumption in the opening and closing coils.

Great current connectors are also used in vacuum contacts. Vacuum connectors are switches which make use of valves compressed in void bottles. These allow suppression of arcs which in turn pushes valves to a smaller size. For this reason, those fuses can be used in dirty processes such as mining. Additionally, vacuum valves are preferred in applications which utilize relatively strong electric energy. This is because they displace oil-filled circuit breakers easily.

Mercury transmitters also utilize connectors. Electric signals in such devices are moved through liquefied mercury. Since mercury reacts easily with air, it is contained in an airtight container. Containers are further lined with insulation materials to prevent heating. For this reason, cycling surfaces which easily corrode with time may utilize such valves. However, usage of mercury relays is reducing since mercury is not environmental friendly. Solid connectors are used in place of these.

Another usage is in mercury-wetted relays. These are transmitters whereby valves are first moistened with mercury before use. However, they may not be categorized as contacts due to the amount of voltage used. Normally, they operate on currents below 15 amperes, unlike other circuits.

Besides the aforementioned applications, contacts are widely used in transformers. Camshafts require a number of fuses to be arranged and used in a sequential manner. Standalone rechargeable magnets are not best suited for such arrangements. Contacts are more efficient since camshafts are controlled by electric engines or gas cylinders. Motor-driven transformers were preferred in plug-in locomotives since they could easily be speed up. They are also used in internally burning locomotives used to control poppet regulators.

Connectors may also be used in magnetic starters. These devices are important in starting electric locomotives. Valves are used to control the amount of energy transferred through coils. At any given time, contacts may not overload. For this reason, they are best for the provision of automatic circuit breaking.