Need some help to set the GenSet please

H

heinz wittenbecher

New member
Mar 1, 1998
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Got my GenSet (6.5kva power drawer) running again but I'm having problems to
get the correct output.

If I set for 60 cycles my noload voltage is 144, with A/C on 125.

If I get the no load voltage to an acceptable level then cycles are too low
and of course even lower when load is applied.

Does the circuit board have anything to do with this or is it strictly the
mechanical adjustments as per user manual.

Any help/suggestions greatly appreciated.

Heinz
 
>Got my GenSet (6.5kva power drawer) running again but I'm having problems to
>get the correct output.
>
>If I set for 60 cycles my noload voltage is 144, with A/C on 125.
>
>If I get the no load voltage to an acceptable level then cycles are too low
>and of course even lower when load is applied.
>
>Does the circuit board have anything to do with this or is it strictly the
>mechanical adjustments as per user manual.
>
>Any help/suggestions greatly appreciated.
>
>Heinz
>
>
>
 
Sounds to me like you have not adjusted the governor, linkage and sped
adjustment correctly.

have you got the maintenace manual, page 24C-26?

If not I can send you the procedure

>Got my GenSet (6.5kva power drawer) running again but I'm having problems to
>get the correct output.
>
>If I set for 60 cycles my noload voltage is 144, with A/C on 125.
>
>If I get the no load voltage to an acceptable level then cycles are too low
>and of course even lower when load is applied.
>
>Does the circuit board have anything to do with this or is it strictly the
>mechanical adjustments as per user manual.
>
>Any help/suggestions greatly appreciated.
>
>Heinz
>
>
>
 
Got it, tried it, but when I set the speed to get proper volts, I'm short
the cycles and if I set the speed (no load) to get the cycles I'm too high
on volts.

>
> have you got the maintenace manual, page 24C-26?
>
> If not I can send you the procedure
>
>
>

> >Got my GenSet (6.5kva power drawer) running again but I'm
> having problems to
> >get the correct output.
> >
> >If I set for 60 cycles my noload voltage is 144, with A/C on 125.
> >
> >If I get the no load voltage to an acceptable level then
> cycles are too low
> >and of course even lower when load is applied.
> >
> >Does the circuit board have anything to do with this or is
> it strictly the
> >mechanical adjustments as per user manual.
> >
> >Any help/suggestions greatly appreciated.
> >
> >Heinz
> >
> >
> >
>
 
>
> Heinz,
> No, the PC board only controls the B+ to the ignition. It
> turns on/off,
> monitors oil pressure and switches power to ignition between
> battery and
> internal alternator circuit.

Rats... I was afraid that'd be the case ;-)

> tech., give me a call at the shop before 10 AM and I'll let you speak
> with one. No, not me, I have been contemplating expanding my
> work force
> and will be interviewing an Onan tech. tomorrow morning,
> maybe you could
> help me see how well he can diagnose over the phone.

I'll take you up on that. I'll try and get up before 7am so that I can make
it by 10 your time :-)

Heinz

>
> Jim Bounds www.gmccoop.com
>

> >
> > Got my GenSet (6.5kva power drawer) running again but I'm
> having problems to
> > get the correct output.
> >
> > If I set for 60 cycles my noload voltage is 144, with A/C on 125.
> >
> > If I get the no load voltage to an acceptable level then
> cycles are too low
> > and of course even lower when load is applied.
> >
> > Does the circuit board have anything to do with this or is
> it strictly the
> > mechanical adjustments as per user manual.
> >
> > Any help/suggestions greatly appreciated.
> >
> > Heinz
>
 
Heinz,
No, the PC board only controls the B+ to the ignition. It turns on/off,
monitors oil pressure and switches power to ignition between battery and
internal alternator circuit.

If you would like to get some input on your problem from a level 3 Onan
tech., give me a call at the shop before 10 AM and I'll let you speak
with one. No, not me, I have been contemplating expanding my work force
and will be interviewing an Onan tech. tomorrow morning, maybe you could
help me see how well he can diagnose over the phone.

Jim Bounds www.gmccoop.com

>
> Got my GenSet (6.5kva power drawer) running again but I'm having problems to
> get the correct output.
>
> If I set for 60 cycles my noload voltage is 144, with A/C on 125.
>
> If I get the no load voltage to an acceptable level then cycles are too low
> and of course even lower when load is applied.
>
> Does the circuit board have anything to do with this or is it strictly the
> mechanical adjustments as per user manual.
>
> Any help/suggestions greatly appreciated.
>
> Heinz
 
All of the specs for the generator are predicated on it being set to 1800
RPM. Output voltage should be no higher than 126 volts with no load and
minimum of 110 volts with full load. At those voltages governor keep the
engine between maximum of 1890 RPMs and 63 cycles and miimum of 1770 RPMs
and 59 cycles.

If you have an accurate tach and the generator is set to 1800 RPMs with no
load and you are getting 146 volts, than your compounding reactor is bad.

These adjustments to the governor are very sensitive and interreactive and
you need to make sure that you have an accurate tach and freq meter to make
them.

>Got it, tried it, but when I set the speed to get proper volts, I'm short
>the cycles and if I set the speed (no load) to get the cycles I'm too high
>on volts.
>
>>
>> have you got the maintenace manual, page 24C-26?
>>
>> If not I can send you the procedure
>>
>>
>>

>> >Got my GenSet (6.5kva power drawer) running again but I'm
>> having problems to
>> >get the correct output.
>> >
>> >If I set for 60 cycles my noload voltage is 144, with A/C on 125.
>> >
>> >If I get the no load voltage to an acceptable level then
>> cycles are too low
>> >and of course even lower when load is applied.
>> >
>> >Does the circuit board have anything to do with this or is
>> it strictly the
>> >mechanical adjustments as per user manual.
>> >
>> >Any help/suggestions greatly appreciated.
>> >
>> >Heinz
>> >
>> >
>> >
>>
>
>
>
 
Accurate freq and volt meter I do have, tach I'm short on.

Assuming rpm out of whack, i.e. not 1800, how easy to adjust and is adjust
even possible?

What/where is the compounding reactor and how easy to find/replace?

TIA - Heinz


> If you have an accurate tach and the generator is set to 1800
> RPMs with no
> load and you are getting 146 volts, than your compounding
> reactor is bad.
>
> These adjustments to the governor are very sensitive and
> interreactive and
> you need to make sure that you have an accurate tach and freq
> meter to make
> them.
>
>
>
>
>

> >Got it, tried it, but when I set the speed to get proper
> volts, I'm short
> >the cycles and if I set the speed (no load) to get the
> cycles I'm too high
> >on volts.
> >
> >>
> >> have you got the maintenace manual, page 24C-26?
> >>
> >> If not I can send you the procedure
> >>
> >>
> >>

> >> >Got my GenSet (6.5kva power drawer) running again but I'm
> >> having problems to
> >> >get the correct output.
> >> >
> >> >If I set for 60 cycles my noload voltage is 144, with A/C on 125.
> >> >
> >> >If I get the no load voltage to an acceptable level then
> >> cycles are too low
> >> >and of course even lower when load is applied.
> >> >

> >> >Does the circuit board have anything to do with this or is
> >> it strictly the
> >> >mechanical adjustments as per user manual.
> >> >
> >> >Any help/suggestions greatly appreciated.
> >> >
> >> >Heinz
> >> >
> >> >
> >> >
> >>
> >
> >
> >
>
 
I managed to get up early enough :-) Thanks for the opportunity to chat,
Jim.

As it may be of interest to others I'll summarize what I came away with from
the discussion.

A "stretch it's life (genset) a little longer suggestion" was to add an
external AVR (Automatic Voltage Regulator). This was predicated on the
genset being ble to maintain a steady RPM and mine seems to be doing that.
I.e. I can set the hertz and it's an acceptable 125 volts if I keep a load
of a heater or the AC on it. And it stays acceptable even when adding more
load, so I'm considering it to be a steady rpm, though maybe not the right
rpm.

Being 'really' reluctant to spend money to repair/overhaul the 22 year old
genset that has 'many' hours on it, my ears really perked up when he
mentioned that he'd done a couple of conversions of a current 5kva Onan to
fit the power drawer, i.e. no having to sacrifice/scrounge for extra space
back there.

Hopefully you had a chance to get some elaboration on both of these
possibilities and perhaps you decided he's a keeper :-)

I'd definately be interested in either or both of these solutions. If I can
stretch the current gensets life a little for a couple of hundred (adding
the AVR) it would give me time to save up for the 5kva conversion :-). I
would've replaced the genset long ago but everyone always wanted the space
of the drawer and behind the drawer and my big house battery lives there and
I ain't giving that up. There has to be a better way.

Thanks again for the opportunity to chat with the Tech. FWIW, it was a good
chat :-)

I guess in the meantime I'm back to regulating the juice with an electric
heater. A/C doesn't get too much use in my neck of the woods :-). At least
the genset is working again.

Heinz

BTW Jim, the time delay module in the shore/genset switch over relay worked
just fine as a replacement in my electrical panel and the relay went into
the spares box as it too will be a suitable replacement.

BTW-2. The no start at all problem was a foil burnt out on the circuit
board. Bridged it with a piece of wire and all is well, or rather it started
after that.

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto:owner-gmcmotorhome]On Behalf Of Jim Bounds
> Sent: Wednesday, July 15, 1998 11:23 PM
> To: gmcmotorhome
> Subject: Re: GMC: Need some help to set the GenSet please
>
>
> Heinz,
> No, the PC board only controls the B+ to the ignition. It
> turns on/off,
> monitors oil pressure and switches power to ignition between
> battery and
> internal alternator circuit.
>
> If you would like to get some input on your problem from a
> level 3 Onan
> tech., give me a call at the shop before 10 AM and I'll let you speak
> with one. No, not me, I have been contemplating expanding my
> work force
> and will be interviewing an Onan tech. tomorrow morning,
> maybe you could
> help me see how well he can diagnose over the phone.
>
> Jim Bounds www.gmccoop.com
>

> >
> > Got my GenSet (6.5kva power drawer) running again but I'm
> having problems to
> > get the correct output.
> >
> > If I set for 60 cycles my noload voltage is 144, with A/C on 125.
> >
> > If I get the no load voltage to an acceptable level then
> cycles are too low
> > and of course even lower when load is applied.
> >
> > Does the circuit board have anything to do with this or is
> it strictly the
> > mechanical adjustments as per user manual.
> >
> > Any help/suggestions greatly appreciated.
> >
> > Heinz
>
 
Compoounding reactor is located at the rear of armature and shown as key 20
on drawing 28.045 of the parts manual.

I am pretty sure from your description of the problem that everything is OK
you just need some adjustments Remember that you are going to have a
frequency change from no load to full load of about 63 to 59 cycles since it
is RPM sensitive. You appear to have close to the proper voltage drop from
no load to load, ie: 146Volts versus 119 (19 volts vs standard 16).

If you have an accurate voltmeter set the engine RPM to equal 126 volts with
no load. Than turn the Air conditioner on and see if it drops to around
110Volts. If it does I would assume the compounding reactor is OK. Just
have to play with the linkage, sensitivity adjustment and governor to get
everything on the curve. The manual says that these settings are interactive
and takes some tweeking.

think you are OK just have to play with it.

>Accurate freq and volt meter I do have, tach I'm short on.
>
>Assuming rpm out of whack, i.e. not 1800, how easy to adjust and is adjust
>even possible?
>
>What/where is the compounding reactor and how easy to find/replace?
>
>TIA - Heinz
>
>
>> If you have an accurate tach and the generator is set to 1800
>> RPMs with no
>> load and you are getting 146 volts, than your compounding
>> reactor is bad.
>>
>> These adjustments to the governor are very sensitive and
>> interreactive and
>> you need to make sure that you have an accurate tach and freq
>> meter to make
>> them.
>>
>>
>>
>>
>>

>> >Got it, tried it, but when I set the speed to get proper
>> volts, I'm short
>> >the cycles and if I set the speed (no load) to get the
>> cycles I'm too high
>> >on volts.
>> >
>> >>
>> >> have you got the maintenace manual, page 24C-26?
>> >>
>> >> If not I can send you the procedure
>> >>
>> >>
>> >>

>> >> >Got my GenSet (6.5kva power drawer) running again but I'm
>> >> having problems to
>> >> >get the correct output.
>> >> >
>> >> >If I set for 60 cycles my noload voltage is 144, with A/C on 125.
>> >> >
>> >> >If I get the no load voltage to an acceptable level then
>> >> cycles are too low
>> >> >and of course even lower when load is applied.
>> >> >
>
>
>> >> >Does the circuit board have anything to do with this or is
>> >> it strictly the
>> >> >mechanical adjustments as per user manual.
>> >> >
>> >> >Any help/suggestions greatly appreciated.
>> >> >
>> >> >Heinz
>> >> >
>> >> >
>> >> >
>> >>
>> >
>> >
>> >
>>
>
>
>
 
Thanks for all the info Thomas.

I'm going to temporarily settle for 128/55 at no load. Turning AC on it
drops to about 114 and the hertz stays at 55. If I lower the volts more the
hertz go down as well so I'm considering this as a compromise.

As I've not had a hertz meter until recently it could've been this way for a
while and only surfaced when the genset crapped out during the last trip
running away on startup ).

I'm still hoping for a new one some day.

Heinz

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto:owner-gmcmotorhome]On Behalf Of Thomas G.
> Warner
> Sent: Thursday, July 16, 1998 10:01 AM
> To: gmcmotorhome
> Subject: RE: GMC: Need some help to set the GenSet please
>
>
> Compoounding reactor is located at the rear of armature and
> shown as key 20
> on drawing 28.045 of the parts manual.
>
>
> I am pretty sure from your description of the problem that
> everything is OK
> you just need some adjustments Remember that you are going to have a
> frequency change from no load to full load of about 63 to 59
> cycles since it
> is RPM sensitive. You appear to have close to the proper
> voltage drop from
> no load to load, ie: 146Volts versus 119 (19 volts vs standard 16).
>
> If you have an accurate voltmeter set the engine RPM to equal
> 126 volts with
> no load. Than turn the Air conditioner on and see if it
> drops to around
> 110Volts. If it does I would assume the compounding reactor
> is OK. Just
> have to play with the linkage, sensitivity adjustment and
> governor to get
> everything on the curve. The manual says that these settings
> are interactive
> and takes some tweeking.
>
> think you are OK just have to play with it.
>
>
>
>

> >Accurate freq and volt meter I do have, tach I'm short on.
> >
> >Assuming rpm out of whack, i.e. not 1800, how easy to adjust
> and is adjust
> >even possible?
> >
> >What/where is the compounding reactor and how easy to find/replace?
> >
> >TIA - Heinz
> >
> >
> >> If you have an accurate tach and the generator is set to 1800
> >> RPMs with no
> >> load and you are getting 146 volts, than your compounding
> >> reactor is bad.
> >>
> >> These adjustments to the governor are very sensitive and
> >> interreactive and
> >> you need to make sure that you have an accurate tach and freq
> >> meter to make
> >> them.
> >>
> >>
> >>
> >>
> >>

> >> >Got it, tried it, but when I set the speed to get proper
> >> volts, I'm short
> >> >the cycles and if I set the speed (no load) to get the
> >> cycles I'm too high
> >> >on volts.
> >> >
> >> >>
> >> >> have you got the maintenace manual, page 24C-26?
> >> >>
> >> >> If not I can send you the procedure
> >> >>
> >> >>
> >> >>

> >> >> >Got my GenSet (6.5kva power drawer) running again but I'm
> >> >> having problems to
> >> >> >get the correct output.
> >> >> >
> >> >> >If I set for 60 cycles my noload voltage is 144, with
> A/C on 125.
> >> >> >
> >> >> >If I get the no load voltage to an acceptable level then
> >> >> cycles are too low
> >> >> >and of course even lower when load is applied.
> >> >> >
> >
> >
> >> >> >Does the circuit board have anything to do with this or is
> >> >> it strictly the
> >> >> >mechanical adjustments as per user manual.
> >> >> >
> >> >> >Any help/suggestions greatly appreciated.
> >> >> >
> >> >> >Heinz
> >> >> >
> >> >> >
> >> >> >
> >> >>
> >> >
> >> >
> >> >
> >>
> >
> >
> >
>
 
>Got my GenSet (6.5kva power drawer) running again but I'm having problems
to
>get the correct output.
>
>If I set for 60 cycles my noload voltage is 144, with A/C on 125.
>
>If I get the no load voltage to an acceptable level then cycles are too low
>and of course even lower when load is applied.
>
>Does the circuit board have anything to do with this or is it strictly the
>mechanical adjustments as per user manual.
>
>Any help/suggestions greatly appreciated.
>
>Heinz

One possibility is a bad freq. meter since both no load and full load are
running too high.
My book says normal is 123 volts no load and 113 full load.

Sometimes rpm can be checked with a fluorescent light plugged into your
garage outlet which is 60 cps. A moving part on the motor such as the
flywheel can be seen to synchronize with the light at 1800 rpm. If engine
speed is too fast, flywheel will appear to slowly move in one direction, too
slow, the other direction.

Along with engine rpm , the Compounding Reactor, a Thyrector across the
Reactor and the Bridge Rectifier are in the regulating circuit and might be
creating a problem.

Book says bridge rectifier output to field winding should be 50 volts DC
with no load.

Reactor pole piece spacing is critical on other gensets I am familiar with,
so presumably is on this one as well. If pole piece spacing has increased
for whatever reason it will decrease the regulation.

Don

ps enjoyed your site
 
I sometimes use a fl light plugged into the MH 110 outlet and monitor via
phototach which will read line sync freq = 120 Hz or 7200 RPM. Adjust speed
accordingly
- -----Original Message-----
From: Donald W. Miller
To: gmcmotorhome
Date: Thursday, July 16, 1998 8:16 PM
Subject: Re: GMC: Need some help to set the GenSet please

>
>>Got my GenSet (6.5kva power drawer) running again but I'm having problems
>to
>>get the correct output.
>>
>>If I set for 60 cycles my noload voltage is 144, with A/C on 125.
>>
>>If I get the no load voltage to an acceptable level then cycles are too
low
>>and of course even lower when load is applied.
>>
>>Does the circuit board have anything to do with this or is it strictly the
>>mechanical adjustments as per user manual.
>>
>>Any help/suggestions greatly appreciated.
>>
>>Heinz
>
>
>One possibility is a bad freq. meter since both no load and full load are
>running too high.
>My book says normal is 123 volts no load and 113 full load.
>
>Sometimes rpm can be checked with a fluorescent light plugged into your
>garage outlet which is 60 cps. A moving part on the motor such as the
>flywheel can be seen to synchronize with the light at 1800 rpm. If engine
>speed is too fast, flywheel will appear to slowly move in one direction,
too
>slow, the other direction.
>
>Along with engine rpm , the Compounding Reactor, a Thyrector across the
>Reactor and the Bridge Rectifier are in the regulating circuit and might be
>creating a problem.
>
>Book says bridge rectifier output to field winding should be 50 volts DC
>with no load.
>
>Reactor pole piece spacing is critical on other gensets I am familiar with,
>so presumably is on this one as well. If pole piece spacing has increased
>for whatever reason it will decrease the regulation.
>
>Don
>
>ps enjoyed your site
>
 
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