Genset sngine monitoring gauges?

I'm putting together a ChangFa 22hp diesel engine and a ST-10 10Kw genhead generator set for shop power and an occasional backup power source for Florida Hurricane season.

I would like to know what engine stats would be a good idea to monitor, i.e. Oil pressure, oil temp, water temp, (running) hours meter (hobbs meter), freq meter. Any others?

I am looking into setting up some kind low oil pressure or low fuel shutdown capability but had concerns about shutting down the genset with loads still applied to the genset.

So, an idea I had would have a high power relay inline before the panel so when a shutdown condition was about to occurred, the relay would open up, dropping the load from the genset then the genset would be turned off in a safe manner.

Genset -->> 240 --> relay -->> fuse panel -->> 120/240 circuits breakers ^ control

Any other idea on how to do this? Then genhead has a capability of 120/240 @ 87/43.5 Amps


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Not exactly engine stats, but I would add two volt meters, one per every leg.

Look at the panel that I made for my Onan DJE diesel generator:

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I have since modified it by adding a three pole 50A switch. makes a control for this sort of purpose.

I am not sure what is the justification for it, but surely you can do it this way. I recently sold two very nice Telemecanique 90A three pole relays with 110v coil, which would be rather nice for this application. I have no more of those relays.

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My thoughts are if you are shutting down on low oil, you need it off right now! I work on standyby generators. None of the units I work on shut down the generator before the engine on a fault of any kind. The controls just kill the engine immediately. I think you are over engineering something. Keep it simple. Greg

Reply to
Greg O

Thanks for your input, the old saying K.I.S.S, you are correct.

My thinking was that I have a well (water) that would need to be run when power is out due to storm or ???, I've heard that if your genset stop running while the well pump is runnng, you risk tearing up the well pump, (how? not sure), which is about 300-400 ft underground, expensive to fix or replace!

If my engine gets to a point of low oil pressure, you are correct, shutdown now! To recharge the winding, due to demagnatizing, when loads are on the genset and engine stops, battery charger and turn the engine over a few time, I'm guessing here on the procedure and the terminology here, so bear with me.

These were my concern, mostly my well getting damaged somehow, I would have to explain to the wife how that happened, if this is the case, Not a fun thing to do!


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Having the power die while the well is running will not hurt the submersible pump.

A close lightning strike or other large voltage surge (well above the motor operating voltage) sure will, though, so make sure the wellhead control box has the biggest lightning arrestor you can get, to try and dump the surge to ground before it goes down the cable.

On modern design alternators you should never have to worry about 'flashing the field' to get them to output power. There is enough residual magnetism to get them started, unless it's been sitting for

20 years.

Even on my 60-year old AC Generator (good-old brush type), I've never had to flash the field on the main exciter or main generator windings, worst has been waiting a few seconds for the brushes to bed through the oxide a bit before the 120V output pops up...

But the stupid little Delco-Remy 12V generator on the engine, that one is a major pain in the butt every time. I just take a 120V battery charger with me and run it off the main generator, which is enough to power the ignition system - till I get around to adapting a modern 12V alternator on there.

And as for emergency shutdown, you have a few choices. If you will be starting the powerplant manually, the simple method is the good old Murphy Switchgauge - it's a set of panel gauges (temperature or pressure) with a contact that the gauge arm hits - simple and reliable. If the oil pressure falls, or the water temp rises, the gauge hits the contact, trips a relay, and kills the ignition. Just about foolproof.

But you have to manually reset the relay and bypass the oil gauge trip during starting, so automatic control is out.

For automatic starting, you use standard automotive "idiot light" senders for the signal inputs, and come up with a time delay to allow time for the oil pressure to build before activating that sender in the kill-switch circuit.


Reply to
Bruce L. Bergman

I have a very old Dayton genset from the early 1960s. It's the older, more robust (but more complicated) rotating wound field, wound stator, as opposed to the newer rotating PM stator designs.

When we first dug it out of the Civil Defense bomb shelter we were de-commissioning, it was in sad shape. It didn't take too long to get the motor running, but even when it ran, and even when the slip rings and brushes were clean, it produced only a couple of volts AC at no-load, and zero into a load.

So we pulled the slip ring end spider and bearing, and tightly clamped some heavy copper wire around the slip rings with hose clamps (to serve as terminals that wouldn't mess up the slip rings). Then we "rang" it with

36VDC from a DC welder. Basically, we just drew and broke an arc to the wire terminals.

It generated after that. There doesn't have to be _much_ residual magnetism in the field... just enough to get it to "self excite". After that, it generates its own field current, and tends to get better with more run time.


Reply to
Lloyd E. Sponenburgh

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