Contact grease

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Contact fat , even e-contact-fat , english contact grease , is an electrically conductive special lubricant with special properties for use in electrical contacts . It is preferably used to improve the electrical contact on relays , switches , breakers and plug contacts that work with low contact pressure. The main objective is to ensure reliable and fault-free electrical contact with a low voltage drop .

Contact bold versus pole bold

Often, contact grease is equated with battery pole grease ( Vaseline ) and in some cases a similar use is implied in product descriptions.

However, like all pure fats and oils, pole fat is not electrically conductive. It does not improve the electrical contact, but protects the contact surfaces from corrosion and the formation of oxide layers due to chemical attack. Pole grease is used in particular for starter batteries in cars, motorcycles, diesel locomotives and aircraft and is also known as acid protection grease .

In contrast, the addition of copper powder , and in rarer cases aluminum powder, makes contact grease electrically conductive.

composition

The basis for contact grease are mixtures of different lipophilic and aromatic compounds which are mixed with electrolytically produced copper powder. Depending on the manufacturer, the appearance of contact grease differs. In most cases, a bronze-like, coppery and shiny color is typical due to the addition of copper. The ingredients and mixing ratios vary depending on the manufacturer.

Contact grease has good compatibility with other materials, including various plastics . It can be used in a wide temperature range, the flash point is over 200 ° C. Contact grease is stable even at moderate minus temperatures.

Material properties

Contact grease is a paste-like lubricant and provides mechanical lubrication, but cannot replace specialized greases for certain applications.

Contact grease protects the treated surfaces or contacts from wear and corrosion. The switch contamination during operation decreases. The electrical erosion of contacts is reduced and maintenance intervals and the resulting service activities can be reduced in many cases. In this respect, the use of contact grease can make sense not only under technical, but also under economic aspects.

Contact grease has a cooling effect on contacts. In the case of manually switched contacts, it supports a consistent feel ("switching feel").

Practical handling

The surfaces of the contacts or connectors to be treated should be clean or bare. As a rule, existing contamination cannot be dissolved by the contact grease, so that its effect remains limited.

Copper paste has a similar composition to contact grease and can serve as a substitute in simple applications

literature

  • Hansgeorg Hofmann, Jürgen Spindler: Materials in electrical engineering . Carl Hanser Verlag, 2013, ISBN 978-3-446-43748-7 , Chapter 7: Contact materials.
  • Hans-Jürgen Blanke, Wilfried J. Bartz, Uwe Jens Möller: Expert Practice Lexicon Tribology Plus. 2010 Terms for study and work, 2nd edition, Expert Verlag, Renningen 2000, ISBN 3-8169-0691-5 .

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