john this is the question in my book that I cant answer???

debbie, June 2009

Indeed-- if the engine was off, and there was no cut out, the dynamo would be trying to turn as a DC motor, and also the dynamo output would rise in accordance with the engine RPM but how relevant would that be these days? Therefore its both A and D....but I'm pleased I don't have that particular textbook! (Long live the alternator with solid state rectifier and voltage regulator) :-)

John, June 2009

It has just dawned on me that the worst case condition is when the engine is not running - without a cutout realy the battery could fully discharge through the stationary generator - and you forget John - Generator = DC and Alternator = AC.

Just what homework are we helping with - 1948 agricultural machinery maintenance course?

There'll be no thanks for either A) or D)...

P, June 2009

I had considered 'A' too, although both are correct.....'A' would be correct if the generator was a DC one...but then thought that the textbook can't be that old! I guess one of us is going to get into trouble.....!

John, June 2009

This is about tractors...

"Cutout Relay - A relay that keeps the battery from discharging through the generator when the generator output is lower than that required to charge the battery. All regulators have a cutout relay. Some earlier tractors had no regulator but had merely a cutout relay."

http://www.antiquetractors.com/terms.htm

So I plump for answer A)

And what book? are we doing your homework for you?

Peccavi, June 2009

Ye gods Debbie and on a sunday too...! I'd go for D really, because if a generator is spinning too fast then the voltage its producing will be too high for the battery to cope with....hence the relay prevents this by opening its contacts. Hope this helps!

John, June 2009