MV Sw Gr - Wiping Contact/Momentary contact

[xabproject]

Client's specification calls for two (2nos) Wiping Contacts as part of the Auxiliary Switch Contacts of a 11kV Sw Gr Breaker. It also calls for "slow closing device". Can some one help me with what purpose do these serve?
thanks in anticipation!

 

[rcw retired EE]

I was told by old electricians that wiping contacts are a type of contact that slides or wipes the surface in the process of closing or opening. Idea is to clean off the contact surface during each operation. (I'd take that definition with some skepticism.)

A slow close device is a maintenance tool, usually a lever that allows the switch to be closed manually in slow motion so the contact sequencing and operation can be observed.

 

[RalphChristie]

Wiping action contacts are "self-cleaning" contacts that wipe or slide against each other when opening or closing a circuit. This wiping action helps prohibit the build-up of any non-conductive deposits on the contacts themselves. Wiping contacts are typically used in AC applications, but are also suitable for low voltage DC applications.

Wiping action contacts can include some limitations on current, voltage, and lifecycle, and they require some form of lubricant, such as grease, to facilitate movement. With repeated arcing, the level of contaminants can increase and be captured by the lubricant around the contact area. This could eventually affect the operation of the switch.

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