ABB Test Switch Configuration 1

[mls1]

With regards to ABB FT-1, 10 pole test switches, we have for years used the part number 129A514G01 which has four PT poles and six current poles. That specific configuration has one of the PT poles on one side of the current switches and the other three on the other side. ABB has a different part number that puts all four PT poles side by side. Is there any reason to have one PT pole on the other side of the current poles? It is usually used for the PT neutral connection so it would become a spare on delta connected PTs. Is there any technical reason this configuration would be preferred?

 

[davidbeach]

Maybe no technical reason, but your field personal may give you heck if you change.

 

[JG2828]

I don't see any real technical reason. However 129A514G01 is extremely popular.
The other switch is # 670B197G18. 129A514G01 has an In Service test plug available, while the other switch does not. In service test plugs were popular in the electromechanical days before relays had built in metering / displays. Also, electromechanical relays had the trip outputs on switches 1 and 10, so that could be the reason it is a popular configuration.

http://ft1switch.com/DataSheet.aspx?FTSw=129A514G01

http://ft1switch.com/DataSheet.aspx?FTSw=670B197G18