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#38969 06/07/04 06:32 AM
Joined: Jun 2004
Posts: 2
cephus Offline OP
Junior Member
During our recent power outage, some of my neighbors had a problem with generators. One owns a gas station and he mentioned that everytime he connects the generators to his gas pumps it destroys the electronic circuit boards of the pumps. I thought that maybe the voltage regulator is not working right in the generator. Has anyone had this problem and if so, what can we do?

#38970 06/07/04 07:27 AM
Joined: Mar 2002
Posts: 582
Ron Offline
Many smaller generators do not have an automatic voltage regulator.

#38971 06/07/04 07:37 AM
Joined: May 2001
Posts: 717
It is often not merely a voltage regulator problem. You need to pay attention to "Total Harmonic Distortion" (THD) and try for the lowest # you can find ( go for under 5%) or the variance will react badly on semi-conductors, sometimes they will not work at all.

#38972 06/07/04 07:44 AM
Joined: Jul 2002
Posts: 8,432
Likes: 3
Hi there cephus,
Welcome to ECN!.
Sounds to me like there is a voltage spike problem, or at the least, a very unstable voltage coming from the generator.
Is there any way that the output can be measured during start-up?.
Failing that, I'd say use some sort of Surge Diversion equipment, could help with the problem.
In the pumps themselves, a type of MOV (metal-oxide-varistor), keeping in mind, that any equipment installed in potentially explosive atmospheres, needs to be rated accordingly!.
Only properly trained persons (petro-chem technicians) should attempt this, I'm telling you!.
Can anyone tell me, are fuel pumps fed by Intrinsically Safe circuits?
Considering they have Fluorescent lights in them.

#38973 06/07/04 08:16 AM
Joined: Jun 2004
Posts: 2
cephus Offline OP
Junior Member
Thanks for the advice about correcting the generator problems. I thought that a buck-boost transformer might eliminate the problems with surges or low voltage occurrences but I didn't think about the harmonics problem. The motors of the pumps might eliminate some harmonics but the circuit boards are definitely seeing some kind of problem.
Do you know of any suppliers that would have a reasonably low cost protection for both the voltage variances and harmonic problems?

I'm not sure there is a MOV on the supply of the circuit boards. If rated correctly, this would eliminate spikes but not the harmonics. Maybe I could place a MOV at the buck-boost transformer, away from the gas pumps.

#38974 06/07/04 10:18 AM
Joined: Apr 2002
Posts: 7,323
Likes: 7
A buck-boost xfr will NOT solve fluctuating voltage problems, and may/could cause additional bad situations. Dependent on the actual load of the circuit that the electronics are on, a good thing may be a "good" UPS unit.

As to the voltage problems, you, or someone, has to stabilize the gen output. In the 'old days', before 'electronics, the gas pumps had no desires for a good 'clean', stable power source, but today it's another story.


#38975 06/07/04 04:52 PM
Joined: Apr 2002
Posts: 2,527
It is possible that the generator is not intended for “smooth” motor starting. The inrush current for most single-phase motors is usually of poor power factor and much greater than the steady-state {nameplate} value.

I would try loading the generator with a purely resistive load—like incandescent lamps—piecemeal approaching the rated load a little at a time. A voltmeter should reflect what you may also see in lamp brightness. That may get you started on resolving the problem. I would not invest in an outboard voltage regulator like a Sola transformer—the results will probably be disappointing. A larger generator, purchased with a guarantee that it will have adequate capacity—may be the only effective solution.

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