Grease for sliding electric switch contacts must meet similar demands as other mechanical sliding surfaces: film strength, appropriate low and high temperature fluid range, and stay-in-place capability. In particular, a switch grease’s ability to prevent wear is critical. Wear debris creates two problems. It can inhibit current flow when the contact is closed, increasing millivolt (mV) drop. When the contact is open, conductive wear debris can cause open circuit resistance (OCR) problems. In either case, switch performance is compromised. When selecting a switch grease, also note that the viscosity of the base oil should complement the contact force of the switch. Low current/low contact force applications require lighter base oils. High current/high contact force applications benefit from more viscous base oils.
The most commonly used switch grease is listed below with more specialist/niche switch grease listed below.
|Product Name||Temp Range (°C)||Rec Contact Force (g)||Up to 1 Amp||1 - 10 Amps||Over 10 Amps||Product & Application Notes|
|RHEOLUBE 362HT||-54 to 125||50||*||*||Light viscosity grease intended for electrical switch contacts. Enhanced temperature stability, plastic compatible. Rust inhibitor.|
|RHEOLUBE 368||-40 to 125||150||*||Medium viscosity, grease for sliding surface applications. Cost effective. Plastic compatible. Used extensively in switchgear.|
|RHEOLUBE 716A||-54 to 150||20||*||*||*||Light viscosity grease intended for electrical contact applications with extended high temp exposure. UV tracer.|
|RHEOLUBE 789DM||-40 to 150||80||*||*||Light viscosity ester grease intended for electrical contacts requiring wide temperature serviceability. Good water/salt water resistance. Plastic compatible. Copper deactivator.|
Lubricants for arcing contacts.
Because the temperatures reached in an electric arc are sufficiently high to degrade any organic molecule, a lubricant’s tendency to “burn cleanly” is a definite advantage. Greases for arcing contacts should be formulated with fluids and thickeners that degrade with fewer by-products than traditional greases. Product recommendation – Nyogel 782D.
Non-burning switch lubricant technology.
Greases that oxidise under arcing conditions pose a special problem for low load/low current applications. Traditionally, cleaner burning glycols (mentioned above – products such as 782D) are used to minimise carbon build-up. A new approach to eliminating problems associated with oxidation is to use Uniflor non-burning perfluoropolyether-based greases. Dispersed in a non-flammable, ozone-safe, fluorinated solvent, these lubricants leave a thin film of grease, ideal for low load/low current applications. Product recommendation – Nyetact 570H-25-UV.
A note about damping greases.
Nye damping greases are widely used on the mechanical elements of many switch assemblies. They serve to reduce noise, improve the tactile feel and improve the perceived value of the mechanical motion involved with electrical switches, that could be hinges, springs and even sliding components. See our application page on Damping Grease for details.
The products mentioned above are the more popular from the range. If you do not find a product that fits your needs then please contact us as we have many more formulations on file for a large variety of switch types.