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Author Topic: Powertec Gen need help  (Read 2153 times)
YeomansEagle
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« on: March 31, 2008, 01:42:12 PM »

Alright Guys

I have a 15 kw Powertec generator. When I started it this weekend everything was fine for 4 or 5 mins. Then I lost all electrical power (engine still running. ) After checking things out I found the reset switch on the generator and reset it. Worked fine for 3 or 4 min. I can reset it but it keeps tripping every few min. Any help would be appreciated.
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JackConrad
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« Reply #1 on: March 31, 2008, 02:14:53 PM »

    Check the bearing in the end cap of the generator. I know several people that have had these fail, some resulting in major generator repair. The clearance between the armature and the fields is very close. The least bit of play in the bearing will cause the armature and fields to touch. Hopefully, yours will not have significant damage.  Jack

PS: PowerTech told a friend of mine that they recommend changing this bearing every 3000 hours. This after his failed @ 400 hours totaling destroying his generator head.
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DrivingMissLazy
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« Reply #2 on: March 31, 2008, 04:24:04 PM »

The first thing I would do is disconnect all the output power leads, at the alternator. Sounds like a simple overload. Also check the output voltage.

Richard
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YeomansEagle
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« Reply #3 on: March 31, 2008, 05:18:11 PM »

I think I may have found the problem. Checking output voltage when everything is working 239-241 volts ac. Just before it trips the reset switch it goes up tp 310-320 volts ac. So my thinking is bad voltage regulator. Thanks for the response.


Leonard Yeomans
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Stan
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« Reply #4 on: March 31, 2008, 06:11:00 PM »

Testing a voltage regulator is a chicken and egg thing. It is in a closed loop where a change in anything makes everything else change.

They are easy to bench test and if it is a time/temperature failure, just apply a fixed voltage  to the input and  a resistor to the output so that it is producing rated field current and let it cook. It should be capable of producing full rated current forever.
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DrivingMissLazy
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« Reply #5 on: March 31, 2008, 07:06:24 PM »

I think I may have found the problem. Checking output voltage when everything is working 239-241 volts ac. Just before it trips the reset switch it goes up tp 310-320 volts ac. So my thinking is bad voltage regulator. Thanks for the response.


Leonard Yeomans

Not necessarily so. The regulator is designed to go to full forcing voltage in case of an overload. If you have something that is shorting out some the voltage regulator would detect a lowering of the output voltage and go into the forcing mode to try and maintain the output voltage. A clamp on ammeter would be the ideal tool to detect a problem such as this.

Richard

You could also probably detect this type of failure by measuring the DC output voltage of the regulator going to the field windings of the Alternator. Probably the leads are identified as F1 and F2 or by a + and - sign.
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« Reply #6 on: April 01, 2008, 05:14:22 AM »

Richard: I thought of that but then I wondered if it was possible to push the generator that high if it was overloaded.
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DrivingMissLazy
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« Reply #7 on: April 01, 2008, 05:39:23 AM »

Richard: I thought of that but then I wondered if it was possible to push the generator that high if it was overloaded.


Stan, you may be correct. Typical exciter maximum input voltage is 63 volts and the regulator typically operates in the 20+ range, so there is plenty of range but an overload may keep the voltage from rising that high.

In order to try and isolate a problem like this I usually used either a variable voltage DC supply to check the operation or several 6 volt lantern batteries connected in series to get up to the correct operating voltage.

It is really important that he disconnect any possible load before trying anything. It will be interesting to find out what the real problem is.

Richard
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« Reply #8 on: April 01, 2008, 06:05:09 AM »

Richard: I completely agree on removing the external load. My main point was that you cannot check a regulator by taking measurements on the generator. Using an external source to excite the field or a bench test of the regulator is the only way to test each part of the system. The regulator response is so fast that an intermittent short or intermittent open will drive the whole system wild.
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Tom Y
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« Reply #9 on: April 01, 2008, 08:57:44 AM »

Have you tried Powertech for help? And if so did they help?  Goodluck  Tom Y
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