Automotive Contactors for High-Voltage Requirements

Q: What is the difference between a relay and a contactor?
A: In general, both terms designate an electromechanical switching device, working on the same physical principle, where a coil is used to generate a magnetic force that mechanically operates an electric contact. While the term relays is widely used in various industries for low and medium power devices, the term contactor is more common in the high power area. The magnetic “motor” is typically realized with a plunger in the center of the coil body for contactors, as opposed to a hinged armature design, which is normally used for relays.

Q: The new generation of contactors works without a gas-filling. What is the advantage of non gas-filled contactors? Can a gas filled contactor rupture?
A: In order to protect the switching contacts, and to support a quick extinguishing of switching arcs, many contactors are filled with pressurized inert gas. Nitrogen or Hydrogen is commonly used, SF6 (Sulfur-hexafluoride) is also applied, mainly in industrial applications. On the flip side, a pressurized gas filling requires a lot more effort in the design and the manufacturing process, to ensure a reliable holding of the gas throughout the lifetime of the contactor. As such contactors must be hermetically sealed by nature, it also bears the risk of rupture, when extremely strong arcing – in case of high over-currents or short-circuits – generates excess gas pressure inside the contact chamber. TE’s latest contactor designs therefore work with no inert gas, also eliminating the need for a hermetic seal. These designs are still environmentally protected against pollution and allow a gas exchange and an equalization of inside and outside pressure, which practically eliminates the risk of rupture in case of extreme arcing.

Read more FAQs about high voltage automotive contactors and relays