Generator only producing 160v ( or less!)

Thepipdoc

Thepipdoc

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My on-board genny was working fine earlier this evening but has now decided to produce only 160v when there is no load but when I switch on an appliance of any sort it drops dramatically to less than 100v.
Is this likely to be the voltage regulator and is this an easy ( for easy read cheap) fix?
Genny is HFL 4kw.
 
Can't say about that genny but they are all sort of the same, the engine powers an alternator and the AVR board regulates the power output.

If you put a meter on a manually rev it up the power should go up, if it stays at the same voltage then the chances are its the avr. Smaller generators have a similar device but it's called a regulator. Also check output before fuse panels and RCD as these have shown faults.

Don't throw it away they can be repaired fairly cheap it's just a question of finding someone local who can do it, even a local guy who repairs lawn mowers will prob help.
 
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Old style genset , I'd say the engine rpm is down, check it with a handheld taco, farryman or kubota unit? Single or twin cyl?. Remember a genny can be many volts down as they produce the volts at the top end of the rev range, the voltage to rpm graph will shop a steel curve at the top end so 50 m down can mean a lot of volts down which some appliances don't like.
 
I don't know that particular generator, but given the symptoms, on any other generator I'd immediately suspect one of the three brushes wasn't making contact with the commutator, either because it was sticking in the holder, or because it was shortened due to wear, or else the copper braid forming the electrical contact had snapped. Seen it many times.
 
The genny voltage is controlled by the field current which is fed via the brushes so if these are dirty then the field can't excite properly. However, the frequency and voltage are also inter-dependant, so a very slow running generator will have a low output voltage.

If it is the latter you will hear the speed drastically slow as the load goes on. Most generators will slow a small amount from zero to full load, and with it the voltage will reduce, but for a 240v nominal output the voltage should not fall below say 220v at full load.

I would check the fuel supply filters and screens (fuel pump ?) as well as the brushes. Bear in mind the voltage from the genny is lethal, so be careful when checking with the thing running, and make sure shore power is isolated and unplugged when the brushes are checked. Do not trust the supply source selector switch to provide safe isolation. Same also goes for an inverter if fitted.
 
I had a HFL generator a 6Kw that did the same thing. There are no brushes in a HFL gennie it self excites the rotor. As part of the system there are one possibly two capacitors inside the control box on the top of the generator itself. If you take the cover off (obviously disconnect shore power first and gennie off) you will see inside a white (probably) tube about the size of a toilet roll inner. There may be two wired in parallel. If you disconnect them and take them down to your local electrical factors they should be able to provide equivalents. They are the same as power factor correction capacitors used in flourescent lights so should be a few quid each. Fit the new ones and fingers crossed you will have power back. If the replacements wont fit inside the existing box on the gennie you may need to make a bracket and run the wires through a gland on the control box to the capacitors. Make sure everything is well insulated and refit the various covers.
 
kashurst said:
I had a HFL generator a 6Kw that did the same thing. There are no brushes in a HFL gennie it self excites the rotor. As part of the system there are one possibly two capacitors inside the control box on the top of the generator itself. If you take the cover off (obviously disconnect shore power first and gennie off) you will see inside a white (probably) tube about the size of a toilet roll inner. There may be two wired in parallel. If you disconnect them and take them down to your local electrical factors they should be able to provide equivalents. They are the same as power factor correction capacitors used in flourescent lights so should be a few quid each. Fit the new ones and fingers crossed you will have power back. If the replacements wont fit inside the existing box on the gennie you may need to make a bracket and run the wires through a gland on the control box to the capacitors. Make sure everything is well insulated and refit the various covers.
Click to expand...

Thanks for the replies people.

Re the above - Is there any way to test the capacitors prior to removal? Will a simple continuity test tell me if one of them has "blown"?
 
sorry no - its a capacitor - you need a capacitance meter. Its probably gone open circuit so a multimeter won't reveal anything. If I'm wrong and its gone short circuit that will measure 0 ohms but if it has I don't think you would be generating any voltage.
 
All, the HFL is farryman 15w powered, self exciting (no brushes).

Simplest DIY check is to change the capacitor. Difficult to test properly without the right kit, but a BASIC function check is:

WITH GENERATOR OFF, AND ELECTRICALLY ISOLATED FROM ANY 240v SYSTEM, DISCHARGE CAPACITOR BY SHORTING ACROSS THE TERMINALS WITH AN INSULATED SCREWDRIVER. DO NOT, AGAIN, DO NOT TOUCH THE TERMINALS WITH ANY PART OF YOUR BODY, DONT TOUCH THE SCREWDRIVER SHAFT.

this stops you getting zapped - it may spark a bit, so don't jump!

Remove capacitor - disconnect it completely.
Apply 12v across the terminals for a few seconds (charges capacitor)
Remove 12v source.
Connect ANALOGUE(digital wont work) multimeter across the terminals set to volts (12vdc range) - needle should kick up and quickly (but not immediately) return to zero as the capacitor discharges across the meter.

This shows it will take a charge, but not if its up to spec. For that you need a capacitance meter, and they're not cheap. A basic continuity test won't work.

If replacing the cap doesn't work, there are two diodes and two thermistors (I think?) wired across the self exciting rotor. You can get to them by removing the cover plate on the end of the alternator, just under the control box. Two 8 or 10mm bolts secure it.

They are soldered in place and fiddle to replace, but worth a try or you need to remove the whole stator assembly to really get to them, and that involves removing the genny from under your aft berth. You should be able to check rotor resistance through here. Check the manual, but I think it's 1.8 ohms per winding, 3.6 ohms for the whole winding as they're wired in series. That last bit is from memory - the HFL manual gives you the full spec of both rotor and stator windings, and the readings to expect.

Very good chance it's the cap (good), also reasonably possible one of the windings has a short (bad).

Do the basic engine rpm checks first, as they're easy!

The HFL is a very simple genny, there's only a few bits that can go wrong.

Good luck! :)
 
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rosssavage said:
All, the HFL is farryman 15w powered, self exciting (no brushes).

Simplest DIY check is to change the capacitor. Difficult to test properly without the right kit, but a BASIC function check is:

WITH GENERATOR OFF, AND ELECTRICALLY ISOLATED FROM ANY 240v SYSTEM, DISCHARGE CAPACITOR BY SHORTING ACROSS THE TERMINALS WITH AN INSULATED SCREWDRIVER. DO NOT, AGAIN, DO NOT TOUCH THE TERMINALS WITH ANY PART OF YOUR BODY, DONT TOUCH THE SCREWDRIVER SHAFT.

this stops you getting zapped - it may spark a bit, so don't jump!

Remove capacitor - disconnect it completely.
Apply 12v across the terminals for a few seconds (charges capacitor)
Remove 12v source.
Connect ANALOGUE(digital wont work) multimeter across the terminals set to volts (12vdc range) - needle should kick up and quickly (but not immediately) return to zero as the capacitor discharges across the meter.

This shows it will take a charge, but not if its up to spec. For that you need a capacitance meter, and they're not cheap. A basic continuity test won't work.

If replacing the cap doesn't work, there are two diodes and two thermistors (I think?) wired across the self exciting rotor. You can get to them by removing the cover plate on the end of the alternator, just under the control box. Two 8 or 10mm bolts secure it.

They are soldered in place and fiddle to replace, but worth a try or you need to remove the whole stator assembly to really get to them, and that involves removing the genny from under your aft berth. You should be able to check rotor resistance through here. Check the manual, but I think it's 1.8 ohms per winding, 3.6 ohms for the whole winding as they're wired in series. That last bit is from memory - the HFL manual gives you the full spec of both rotor and stator windings, and the readings to expect.

Very good chance it's the cap (good), also reasonably possible one of the windings has a short (bad).

Do the basic engine rpm checks first, as they're easy!

The HFL is a very simple genny, there's only a few bits that can go wrong.

Good luck! :)
Click to expand...
Thanks for the extensive reply - much appreciated.
I intend to head over to the boat one night this week and will take a look and report back what I find.
 
Spoke to Opal Marine today and have ordered a replacement capacitor and a pair of diodes from them.
The guy I spoke to ( Mark) very helpful and he said he sees this issue all of the time on HFL gennies.
For the cost ( £39) he said it would be easier to eliminate both items and fit new replacements.
They'll be delivered tomorrow and I'll fit them this weekend, so fingers crossed that's all it is.
 
I'd do the capacitors first and try it again before plunging into the diodes
might save a bit of time and skinned knuckles
 
Thepipdoc said:
Thanks for the extensive reply - much appreciated.
I intend to head over to the boat one night this week and will take a look and report back what I find.
Click to expand...
Fitted the new capacitor tonight and it made no difference - it was producing 160v and then after 5 mins of running it stopped producing any voltage!
I couldn't find where the diodes are on the gennie and would appreciate it if anyone out there has a manual for the Farymann 18w model. (Its actually a HFL but I'm reliably informed its Farymann that produce these gennies so either a HFL or Farymann manual would be good.)
 
The diodes are soldered onto the end of the rotor.

Under the ac control box, on the end face of the generator, just above the water pump, you will find a small rectangular cover plate. This may well have the dc charge components (rectifier and metal finned resistor) attached to it.

It's held on with two bolts - remove them and the dc charge bits (if fitted..) and pull off the cover plate. This will reveal the top part of the end of the rotor. The diodes are here, one on each side of the rotor (180deg apart) and wired in parallel with blue thermistors (I think they're thermistors - they may be thermal fuses. They're something to do with temperature, anyway!). You may need to rotate the engine by hand to line the diodes up with the opening in the generator.

They WILL be a bitch to change in situ, but it is possible. Needle nosed pliers, steady hands etc....

Edit: while you're there, probably worth changing the blue things too...

If that doesn't work, you've almost certainly got a failed winding, which sounds plausible with your symptoms. One half goes open circuit, gen output halfs, second part of winding then overheats trying to compensate. This, unfortunately, requires total disassembly and a rewind of the windings. Budget c£800 per winding....Sorry!
 
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Ps you will need the HFL manual. The faryman manual only deals with the engine, not the alternator.

Sorry!

If it needs a rewind, I have personally used http://www.southernrewinds.net/

No connection, they did my faryman powered zeise unit when I accidentally destroyed the stator winding. Annoyingly by my own stupidity!!
 
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