john_morris_uk
Well-known member
A salutary story.
One day left of an extended voyage and our Whisperpower Piccolo Generator suddenly stopped. It was brand-new and had only been in use for a few months.
The Piccolo generators have a diesel engine with a fixed magnet alternator that produces 400+ volts AC that goes to a device called a PMG that controls the generator and also converts the 400+V to 230 V pure 50hz sine wave. When it stopped, the fault came up in the panel as PMG failure.
So I assumed the failure was fatal and a new PMG electronics magic box would be required under warranty.
Emailing the supplier produced no reply. (I’m still waiting two weeks later!) Consulting the local agents and they consulted the manufacturers who said that there were five faults that could produce that warning light indicator. The only one we could reasonably be expected to check ourselves was a fuel failure. Basically, if there is a fuel failure the engine slows down the 400 V goes out of range for the PMG and the PMG shuts down the engine and shows PMG failure as the fault…
We checked through the fuel line and even took the CAV filter out to see if there was a problem. The filter was immaculately clean (it should have been with a brand new fuel tank and only clean fuel for the previous few months ) and we could find no fault in the fuel line at all. Fuel was getting through to the injector pump when we pumped the hand pump (that I’d fitted on the CAV filter to help with the bleeding process) and it was bled perfectly.
The symptom now became that the generator would start and run for a few seconds and then shut itself down with the fault coming up as PMG failure. A multimeter on the stop solenoid show that the PMG was only demanding that the generator stopped when the revs died away. Fuel was obviously not getting through in sufficient quantity, and although there was no sign of contamination or blockage in the coarse filter the only filter left was the fine filter. We reluctantly agreed that the only course of action was to replace this in the hope that there was some sort of blockage in there. However as I groped around the side of the generator I discovered the real fault. When we had been doing initial running checks on the engine a few weeks previously, my friend and colleague had noticed that the exhaust was dripping slightly at one of the junctions. Specifically the exit from the generator itself where the hose connected to the water trap and from there to the water separator before separating water (being discharged below the waterline) and fumes (being discharged above waterline). It’s a slightly complex exhaust system with a lot of connections. Obviously where the hottest connection was, adjacent to the engine, the hose had settled and allowed a drip of seawater to appear from time to time. The T clamp was tightened and the drip stopped and we thought nothing more of it. What we hadn’t noticed was that the drip had gone onto a connector to the electric fuel pump for the generator which was hidden and almost out of sight. The connection was corroded and produced an intermittent fuel pump.
New connections made and subsequently sprayed with anticorrosion spray and the generator is back up and running again perfectly.
So a fault that appeared as PMG failure was actually an electrical fault to the electric fuel pump of the generator causing it to slow and that caused the PMG to stop the generator and signal that it was faulty. A lesson learned.
One day left of an extended voyage and our Whisperpower Piccolo Generator suddenly stopped. It was brand-new and had only been in use for a few months.
The Piccolo generators have a diesel engine with a fixed magnet alternator that produces 400+ volts AC that goes to a device called a PMG that controls the generator and also converts the 400+V to 230 V pure 50hz sine wave. When it stopped, the fault came up in the panel as PMG failure.So I assumed the failure was fatal and a new PMG electronics magic box would be required under warranty.
Emailing the supplier produced no reply. (I’m still waiting two weeks later!) Consulting the local agents and they consulted the manufacturers who said that there were five faults that could produce that warning light indicator. The only one we could reasonably be expected to check ourselves was a fuel failure. Basically, if there is a fuel failure the engine slows down the 400 V goes out of range for the PMG and the PMG shuts down the engine and shows PMG failure as the fault…
We checked through the fuel line and even took the CAV filter out to see if there was a problem. The filter was immaculately clean (it should have been with a brand new fuel tank and only clean fuel for the previous few months ) and we could find no fault in the fuel line at all. Fuel was getting through to the injector pump when we pumped the hand pump (that I’d fitted on the CAV filter to help with the bleeding process) and it was bled perfectly.
The symptom now became that the generator would start and run for a few seconds and then shut itself down with the fault coming up as PMG failure. A multimeter on the stop solenoid show that the PMG was only demanding that the generator stopped when the revs died away. Fuel was obviously not getting through in sufficient quantity, and although there was no sign of contamination or blockage in the coarse filter the only filter left was the fine filter. We reluctantly agreed that the only course of action was to replace this in the hope that there was some sort of blockage in there. However as I groped around the side of the generator I discovered the real fault. When we had been doing initial running checks on the engine a few weeks previously, my friend and colleague had noticed that the exhaust was dripping slightly at one of the junctions. Specifically the exit from the generator itself where the hose connected to the water trap and from there to the water separator before separating water (being discharged below the waterline) and fumes (being discharged above waterline). It’s a slightly complex exhaust system with a lot of connections. Obviously where the hottest connection was, adjacent to the engine, the hose had settled and allowed a drip of seawater to appear from time to time. The T clamp was tightened and the drip stopped and we thought nothing more of it. What we hadn’t noticed was that the drip had gone onto a connector to the electric fuel pump for the generator which was hidden and almost out of sight. The connection was corroded and produced an intermittent fuel pump.
New connections made and subsequently sprayed with anticorrosion spray and the generator is back up and running again perfectly.
So a fault that appeared as PMG failure was actually an electrical fault to the electric fuel pump of the generator causing it to slow and that caused the PMG to stop the generator and signal that it was faulty. A lesson learned.
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