Afternoon chaps,

An old friend of mine who collects scrap and often brings bits round to me for identity and possible sale sold me what said on the label was a DC generator of some 110 volts. As a quick check I tried feeding it with about 50 volts of DC and away it went. I dismantled it as far as necessary, checked it all for brushes, bearings and internal wiring, it was all fine, but the first time I tried to use it, it was spinning around quite fast on the belt drive from a more powerful mains motor. but no sign of any DC output. thinking that it might not be spinning fast enough, I cranked up a big battery charger I had made capable of over 100 VDC and away it went. At top speed, I put a voltmeter across the input and measured the voltage, however as soon as the DC was switched off the voltage died straight away, although the generator continued to rotate for a bit. I did this to prove that it was not an excitation issue as sometimes I have found that generators of various kinds need to have a jolt to get them going.

In fact, I have an ac alternator of some 5 KW 240 VAC and this does a very similar fault I have tried all sorts of ways to get this going as it is a US Wisconsin (?) petrol engine set and I would love to get that to work OK

Come to think of it I have also a set with a 2 cylinder Armstrong Siderly diesel engine of about 10 KW 3 phase and if I put a load on of more than a Kw or 2 it just switches off? There is no overload device or anything.

Is this something to do with me and my suspected magnetic personality or is there a more logical explanation. Or is it as I have always suspected all mechanical devices have secret minds of their own and the best thing is to find ways to live with them. Perhaps they are just getting TOO excited, as getting them excited has been uppermost in my mind.

If anyone has experienced this peculiar behaviour and knows the answer(s) I should be very glad to hear of it.

Thanks and regards George.