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Operation of the pivot lamp of multiple Junction Indicators

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Operation of the pivot lamp of multiple Junction Indicators

Unread postby John Webb » Wed Mar 16, 2016 5:34 pm

We're now starting to sort out the way in which we will work our recently acquired LED signals. I was trying out our position 4 and 5 'Feathers' this afternoon and realised that I was uncertain how the common 'pivot' lamp was lit when one or other JI was selected. Did it have it's own relay operated by the interlocking when either JI was to be lit? Or did they use contacts on the appropriate JI relays wired in parallel so that the pivot lamp was lit when either JI relay was operated? (The Green IRSE book only looks at a single JI situation.)
Last edited by John Webb on Fri Mar 18, 2016 3:00 pm, edited 1 time in total.
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Re: Operation of the pivot lamp of multiple Junction Indicat

Unread postby JRB » Wed Mar 16, 2016 11:28 pm

I don't know, but would be prepared to bet that it has varied over the years and over the regions/railways.
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Re: Operation of the pivot lamp of multiple Junction Indicat

Unread postby Mike Hodgson » Thu Mar 17, 2016 12:23 am

another complication to think about on that - don't forget that JI proving calls allows up to 2 of the 5 bulbs to fail but the main aspect should not clear to a proceed if more than two fail
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Re: Operation of the pivot lamp of multiple Junction Indicat

Unread postby AN106 » Thu Mar 17, 2016 8:26 am

The latest typical circuit is can be found on NR code of practice sheet T28430 version 3, which is for a position1 and 4 PLJI. This shows a 110V AC circuit, with a common UECR (PC065) current proving relay, which picks if the current drawn is equivalent to 3 or more bulbs. The four Position 1 lights are driven over the 'A' Route UHR, Position 4 lights over the 'C' Route UHR and the pivot light over both UHRs in parallel. There is a common NX110 return which uses both UHRs in parallel for double cutting.

Additional - I forgot to add that this assumes the bulbs (if filament type) are driven from transformer/rectifiers (TJs) mounted in the PLJI units. If you have an older style of head with the bulbs directly fed, obviously you would use DC circuits of the right voltage, with a different specification of UECR. LED signals don't have the TJs.
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Re: Operation of the pivot lamp of multiple Junction Indicat

Unread postby John Webb » Fri Mar 18, 2016 11:15 am

My thanks to AN106 for more information sent direct to me. The Pivot lamp is lit by extra contacts on each JI selection relay wired in parallel so that the operation of any one JI also lights the pivot lamp without the use of a separate relay.
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