traction current bleed resistors

[neilw]

Hi there

Has anyone got any information and/or photos about the traction current bleed resistors at the end of the traction current sections, please? We're in need of something for the Tramway Museum so any information would be helpful, thanks. Info such as current rating, resistance value, and potential suppliers (sorry for the pun....)

many thanks

[goldenarrow]

I think resistance stood at 220 ohms on the negative rail and 110 ohms for the positive rail. This was in the early 2000's, I'm unsure if the 750V upgrade on the SSR has changed this though.

[roythebus]

As a matter of interest, what do they do?

[bananaman]

May 7, 2018 8:18:36 GMT roythebus said:

As a matter of interest, what do they do?

They provide an Earth reference, which is how we end up with a +420v rail (the posi) and a -210v rail (the negi). This known earth reference makes it easier to detect unwanted earths, i.e. a short between a con rail and a running rail.

[bananaman]

Or +500v and -250v to my SSR colleagues....

[neilw]

many thanks goldenarrow