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Old 9th Feb 2018, 11:54 pm   #8
russell_w_b
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Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
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Default Re: How were annunciator panels signwritten?

Quote:
Originally Posted by Bookman View Post

One type yes; this being a two element version of the normal 4 element withdrawable TAA 41 or was that TA41? In this case, there has been a gas surge detected by the Buccholz device that would be assembled on the power transformer.
I didn't show the non-executive Buchholz alarm relay. The PBO in question was for the 11kV / 8.9kV rectifier transformers on one of the Marconi B6122 250kW HF transmitters, which we no longer have; the OCBs being racked out and shutters locked off. The AR64 excitron rectifiers were swapped out with silicon diodes back in '83 but the annunciator labelling remained the same!

We used to test the PBOs by connecting a foot-pump to the Buchholz pet-cock and filling the chamber with air. Gas tests were with silver nitrate solution.

Before my time the HV mimic panel had the semaphore indicators you mention, but it now has red/gn LED paths and commercially-engraved labels. We still employ Faraday disc IDMT relays in some places, and other PBO annunciators. More fun than MCGG and MiCOM stuff!
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