Electrical contacts are ever-present in just about everything we use every day. If a piece of equipment, machinery, device or appliance runs on electrical current, there are several electrical contacts powering the current. Here is a brief tutorial of what electrical contacts are and what they’re used for.
An electrical contact is the part of an electrical circuit that completes the power circuit to allow electrical current to flow from point A to point B. When the power circuit opens, that current flow stops; when it closes, the connection is complete, and the current flow powers the electrical machinery being used.
Electrical contacts are used in power distribution applications such as; switches, circuit breakers and relays. Diesel-electric trains, light rail vehicles, historic trollies, nuclear submarines, electric cars, mining trucks, oil and gas drilling motors and basic applications such as a light switch or small appliances.
Electrical contacts and the contact tips are made from a range of materials, based on several variables.
Materials and Why They Are Used
Copper is the common material used for electrical contact backings. The powder metal contact tip is the conduit for the power circuit to complete the flow of power. When selecting materials for the contact tip, the goal is to get the optimal voltage and wear from the material that gives the electrical component the highest ratio of success. A general rule of thumb is that as conductivity increases, resistance decreases. The thermal conductivity rises, but erosion also increases. For example, a silver electrical contact tip is brazed to a copper backing and is a superb conductor, but because the tip is pure silver, the silver tip can degrade and erode quicker. For that reason, even if silver electrical contacts are the least expensive electrical contact tips available, there are alternative metals to be added to the silver to increase the longevity of the electrical contact part.
An electrical contacts manufacturer can mix the silver with metals like carbide and tungsten to make the powder metal contact tips more conductive, resistant and last longer. Often silver electrical contact suppliers offer silver carbide and silver tungsten contacts because these metals combine superior conductivity of the silver with the ability of carbide and tungsten to withstand mechanical and electrical wear for longer periods of time. These tips will cost more upfront but if your train, mining truck or drilling motor runs longer with less downtime, you are saving money in the long run.
There are other materials used for electrical contact tips based on the power and voltage requirements of the devise. Other electrical contact tip materials include:
Gold: It’s highly conductive but very malleable.
Silver Tungsten Carbide: It’s resistant to contact sticking, welding, and oxidation. Because it’s a harder material, it’s more resistant to arc erosion and contact wear.
Copper: Copper is highly conductive and durable.
Copper Tungsten: This is a low-cost alternative to silver tungsten or carbide. These are used in applications such as oil and gas filled devices.
Other materials used in contact tips include silver graphite, silver tungsten carbide graphite, silver molybdenum, silver nickel, and copper graphite.
Electrical contacts have become highly specialized and can be applied to components to achieve optimal functionality, longevity, and effectiveness. The type of powdered metal electrical contact tip for the electrical contact depends on the applications power requirements. For more information about which electrical contact and powder metal tip to use for your application needs, visit Hoyt.