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Generators & Motors General Discussion Antique Generators, Light Plants and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Motors General Discussion

1967 Hercules generator


I recently aquired a '67 military hercules generator. I was told that the generator was toast but...

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  #21  
Old 09-26-2007, 10:43 AM
rasuth rasuth is offline
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Default Re: 1967 Hercules generator

I was not clear.

As long as the MEP-018 is functioning under AVR control, it is fine. Even the 'stock' AVR has 2-3% voltage regulation performance. However, it is pretty common for the stock AVR to fail, and there is no 'safety' circuitry to sense this and turn-off the output. Most new AVRs have this capability, and regulate to <1%.

What is NOT a good house generator is a 'resonant self-exited' generator. I have a little 3kW diesel (military surplus) that is like this, and would work fine for 'reactive' loads (motors), but could cause problems with some electronics (TVs, Stereos, Computers, etc).

In my case, the 3kW barely will run the well head. Since I am out of town alot and my wife is not particularly adept at survival skills under adverse conditions, I needed a 10-15kVA plant to support the Heat Pump (fans and compressor), well head, and the more sensitive electronics. The MEP-018 should be perfect for this as long as I can get the auto-start and AVR issues worked out. Otherwise, it works fine (since it sucks alot of gas, I may opt for the less efficient propane or dual fuel-conversion as well).
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  #22  
Old 09-26-2007, 12:02 PM
Raymond Raymond is offline
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Default Re: 1967 Hercules generator

How about a few pix of the inside of the control panel. The schematic picted is only the on-engine control and apparently the connector bundle is missing from the generator to the panel. It's easy to reconnect because the military units are very logically connected with connection and circuit numbering. The wire numbers use the "from- to" designation like Cat. It's no doubt a stout machine and would make a dependable stand-by but you'll have to deal with the old gasoline problem and it probably burns 1.5 gal.hr. unloaded and the noise will be obtrusive. From the appearance it will take a seasoned pro to get it back in shape and unless the engine is perfect, and the generator stator and rotor not dammaged, not worth fixing.
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  #23  
Old 09-26-2007, 06:23 PM
rasuth rasuth is offline
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Default Re: 1967 Hercules generator

Ok. But out of town now. Will take pictures and post this weekend.

Almost all of the value of the MEP-018 is in the generator head. Agreed, if it's toast don't bother. Anything running at 3600RPM (must be pretty well governed) will drive it, but the 4A-084s have alot of parts availability so should be easy to maintain. I'd stay with them.

There is a 'field flash' spring return switch on the panel, so make sure there is a residual magnetic field before writing off the head.

The AVR is in an aluminum cage with a 14-pin (?) metal shell bayonet connector that is easily removed. The same AVR is used in a 5kVA generator, but is connected along a terminal strip instead.

A neat trick is to bolt the top of the hinge panel to the frame with the 'Dzus' screws and then unscrew the lower panel screws (not Dzus, but standard machine screws) and lift the bottom panel up. You can then see the AVR, which is held in place with four screws on the corners.
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  #24  
Old 09-26-2007, 10:46 PM
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Jim McIntyre Jim McIntyre is online now
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Default Re: 1967 Hercules generator

Quote:
Originally Posted by rasuth View Post
...Since I am out of town a lot and my wife is not particularly adept at survival skills under adverse conditions... The MEP-018 should be perfect for this as long as I can get the auto-start and AVR issues worked out.....
Out of town + wife not adept at 'survival skills' will NOT make a good situation for a 40 year old back-up genset. These MEP series of gensets are fun to tinker at, and make a decent back-up supply, but only if you're around to turn wrenches as needed.

If I were in your shoes, I'd be looking at a brand-new 'packaged' autostart genset, running on LP or natural gas.

As a far distant second choice, convert the MEP to LP, install a new voltage regulator, figure out how to implement a reliable SAFE autostart, and hope for the best...
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  #25  
Old 09-30-2007, 08:37 PM
rasuth rasuth is offline
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Default Re: 1967 Hercules generator

You might be right, but I have hopes :-)

Here are the pictures of the internal compartment. I was wrong about the location of the AVR, it is on the lower left of the compartment. In the upper right is the field flash switch (not on the front panel).
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IMG_0666_1.jpg   IMG_0667_1.jpg  
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  #26  
Old 10-01-2007, 12:16 PM
Raymond Raymond is offline
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Default Re: 1967 Hercules generator

Looks like the exciter is missing but can't tell because there appear to be a lot of Gen lead connections in the upper right corner which is truncated and Mag amp units have a gen coil connection on both ends of all coils. Where does the plug in the lower left corner go?. The field flash switch is commonly used with static exciters because they have no residual and must be flashed every time it is started unless there is an auto flash system.
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  #27  
Old 10-01-2007, 02:20 PM
rasuth rasuth is offline
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Default Re: 1967 Hercules generator

The 'exciter' is the AVR. It senses the output voltage of the generator and controls the current through a field coil (about 30 ohms). Voltage is supposed to be around 32V.

Yes,it is missing. I was doing this late last night and found that the images had to be decimated (to get to the ~197k jpeg limit) and that I could only upload two at a time.

I got impatient.

The cylindrical connector laying on the floor of the bottom part of the compartment connects to the AVR. Nothing else is missing or disconnected except for the rheostat that 'fine tunes' the AVR voltage, and those are the three wires dangling. I pulled it out to use in going through the AVR diagnostics.

The normal failure mode on the AVR appears to be due to the T0-3 resistor. Unfortunately, mine is more complex.
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  #28  
Old 10-01-2007, 02:21 PM
rasuth rasuth is offline
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Default Re: 1967 Hercules generator

Arrgh.. Transistor, not resistor.
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  #29  
Old 10-01-2007, 08:57 PM
Raymond Raymond is offline
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Default Re: 1967 Hercules generator

The AVR controls the current through the saturable transformers. Their output is connected directly to a diode bridge which feeds the field through the brushes. The avr works backwards ie as the voltage falls, the output is lowered. This is because the DC output to the transformers acts to lower their turns ratio and hence their output. The maximum output of the exciter occures at "0" output of the vr. If the vr fails you can replace it with a rheostat using the original control power supply transformer and diodes to produce the DC. The system is inherently self regulating. I believe the no load operating current in the DC control circuit was around .8 amps at 120 volts gen output. I ran my Bogue 15 KW (SF-15-MD) Military, for 2 years this way before I got around to fixing the regulator. The regulator eliminates the voltage change due to heatup (it drops 3-5 volts) and increase on load pickup (it rises about 5 volts at 50% load). As a quick test just remove the vr output wire that connects to the transformers with it running and the voltage will jump up to around 300V then the unit should shut down on high voltage.
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Old 10-02-2007, 12:06 PM
rasuth rasuth is offline
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Default Re: 1967 Hercules generator

You may be right. Power Electronics is not my field.

But if you look at the schematic, the AC voltage from the generator is fed into a transformer that feeds a bridge rectifier sourcing a high voltage opamp (wow.. it's a hybrid, too. Haven't seen one of those in awhile) that controls the TO-3 current (through a TO-5 transistor.. can't remember if it's a Darlington configuration) by comparing the sensed, rectified voltage to couple of zener references. The field coil is in the collector of the TO-3 NPN, so it looks to me just like a static current control.

Where is the saturable transformer?
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  #31  
Old 10-02-2007, 08:30 PM
Raymond Raymond is offline
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Default Re: 1967 Hercules generator

Not having seen the schematic I couldn't say, but I don,t believe a current control off the stator would work very well as the source voltage variation would produce a unstable field output and suffer gross field foldup on load application. Even though Power-tronics has a static exciter module but it is large and has 100 amp scrs. the power required for the field is roughly 7.5% of the generators output. That's 750 watts for a 10 KW machine and I doubt that a little transistor can handle that kind of power. If you go back on the board and look down there is a thread "international diesel electric & John Reiner 40 KW". At the bottom (last entry) is a picture of a 15 KW static exciter from my 15 KW bogue built in 69. The regulator is on top and the transformers and diode bank below. If yours doesn't resemble this, I don't know what you have. There are three sets of compound wound (shared armature) saturable transformers with current transformers connected directly to the output diodes which feed the field brushes.
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  #32  
Old 04-18-2009, 08:57 PM
Don W Redington Don W Redington is offline
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Default Re: 1967 Hercules generator

Quote:
Originally Posted by buzzboy View Post
I recently aquired a '67 military hercules generator. I was told that the generator was toast but the motor still ran fine. So far I haven't gotten it to turn on quite yet.

I attempted to electronically start it but realized that it runs a 24 volt system. I don't know though whether it will turn over or not on just 12. Will it?

I have also tried to pull start the engine but the compression is high enough that I can do absolutely nothing. The original owner told me that there was a way to lower the compression for pull starting the engine? Is this so? If so where is it located?
Hello,
I have no clue what I am doing with this computer. I am a gears and grease sort of guy. I bid a military surplus generator this week and ended up with 2 of them. My interest is in only the engine. If you are interested in any of all the generation pieces we will be able to make it happen. I highly believe the unit to be servicable as it was being used until the magneto on the engine went south. There were 5 units total, all being used as emergency power for a small town in Kansas. I understand they went to propane for the availability of easy access to fuel when the power was down.
Don W Redington
316 943 6760 316 516 0704
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