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Electrical AC Phase power distribution.


Zaherk
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Had a AC phase distribution diagram where each and every switch,light,valve,pump,instrument,etc. power source was shown, whether it was 3 phase or single phase, from what phase on a specific Bus. Can anybody help, please? Only the fairies will know what happened to my copy.

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Tiny Clark,

Our Herc Ser no 4475, Model L100-30 1972.

We had the Ess AC B phase CB\'s popping on us during just about every flight. No bus off light but during taxi when you check your Aux feather pump motors for a load increase there is no loadmeter increase but your Ess bus off light illuminate. Releasing the Condition lever the Ess bus off light goes out and everything looks normal until you open the 245 to find the B phase CB\'s popped. Changed the Aux hyd pump, no CB popping for two flights and then she was back to popping. The Sparkies found some of those B phase CB\'s popping at 17 amps instead of the rated 35 amps. They changed the CB\'s. So far no problems.

If you\'ve got a schematic of the Ess and Main, what gets fed of each phase would be greatly appreciated.

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  • 3 weeks later...

n1dp,

The Sparkies found some of the Ess AC Bus B phase CB\'s popping at 17 amps instead of the rated 35 amps. They changed the CB\'s. So far no problems. Suppose that\'s why we thought it was the Aux pump, the initial spike when you switch the pump on caused a higher than 17amp current draw which popped the damaged CB. Not once did one of the auxpump CB\'s popped. In hindsight, only the Ess Ac bus B phase CB\'s popping and not the Aux pump CB\'s was trying to tell us something but we did not listen.

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  • 1 month later...

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