Any generator experts out there?
 

Greetings,

I have a Westerbeke 4.0KW gas genny in my boat, and I'm experiencing
the following: The genny runs like a sewing machine, and when first
started, the voltage settles right at 115. When a load is presented
(A/C for example), I'll get the typical drop from the load while the
genny adjusts, and then the genny will settle back to around 115. All
is well at this point. The problem is, when the load is removed (when
the A/C cycles), the voltage rises to 150 and stays there. I notice
an increase in engine speed as well.

My initial thought is that the voltage regulator might have gone
south, but I don't know if this would explain the rise in engine
speed. I guess if the regulator doesn't control the voltage, the
engine speed will rise accordingly to satisfy the higher voltage, but
I'm no electrical engineer, so it's just a guess.

Any input would be greatly appreciated! I'm planning an anchor-out
this weekend, and with the rains and heat/humidity in FL, I can't be
without A/C!!!

Any generator experts out there?
 

Some generators have a rpm governor that controls the output voltage.
Sounds like yours is one of those and it's sticking open too far. When
you add a load the engine throttle gets opened further to keep the rpm
constant. When the load is removed the engine throttle is not being
backed off thus the increase in speed and voltage.

wrote:
Greetings,

I have a Westerbeke 4.0KW gas genny in my boat, and I'm experiencing
the following: The genny runs like a sewing machine, and when first
started, the voltage settles right at 115. When a load is presented
(A/C for example), I'll get the typical drop from the load while the
genny adjusts, and then the genny will settle back to around 115. All
is well at this point. The problem is, when the load is removed (when
the A/C cycles), the voltage rises to 150 and stays there. I notice
an increase in engine speed as well.

My initial thought is that the voltage regulator might have gone
south, but I don't know if this would explain the rise in engine
speed. I guess if the regulator doesn't control the voltage, the
engine speed will rise accordingly to satisfy the higher voltage, but
I'm no electrical engineer, so it's just a guess.

Any input would be greatly appreciated! I'm planning an anchor-out
this weekend, and with the rains and heat/humidity in FL, I can't be
without A/C!!!

Any generator experts out there?
 

On Thu, 13 Jul 2006 14:38:35 -0400, wrote:

On Thu, 13 Jul 2006 13:30:51 GMT, wrote:

Greetings,

I have a Westerbeke 4.0KW gas genny in my boat, and I'm experiencing
the following: The genny runs like a sewing machine, and when first
started, the voltage settles right at 115. When a load is presented
(A/C for example), I'll get the typical drop from the load while the
genny adjusts, and then the genny will settle back to around 115. All
is well at this point. The problem is, when the load is removed (when
the A/C cycles), the voltage rises to 150 and stays there. I notice
an increase in engine speed as well.

My initial thought is that the voltage regulator might have gone
south, but I don't know if this would explain the rise in engine
speed. I guess if the regulator doesn't control the voltage, the
engine speed will rise accordingly to satisfy the higher voltage, but
I'm no electrical engineer, so it's just a guess.

Any input would be greatly appreciated! I'm planning an anchor-out
this weekend, and with the rains and heat/humidity in FL, I can't be
without A/C!!!


This is an alternator so engine speed only affects frequency. The
regulator may in fact be bad but if it really increases engine speed
there is another problem. I would suggect getting it looked at by
someone with the tools to see what is really going on.

You don't get the power for free, so under load the gas engine driving
that alternator/generator must increase its throttle setting to keep
up with the increased demand. When the demand goes away, the throttle
evidently isn't closing back down, and the engine speed increases
without that extra load on it. If poorly regulated, that can increase
the voltage output as well. Think of your car idling with the lights
on, the rev it up... the lights get brighter. Conversely, keeping the
same engine speed turn the headlights off, and the voltage will rise.

Does the engine speed ever slow back down on its own? Could it be as
simple as a broken/missing throttle return spring? Or maybe a binding
throttle linkage.

Any generator experts out there?
 

On Thu, 13 Jul 2006 19:32:34 -0400, wrote:

On Thu, 13 Jul 2006 22:13:39 GMT, Jack Goff wrote:

Think of your car idling with the lights
on, the rev it up... the lights get brighter. Conversely, keeping the
same engine speed turn the headlights off, and the voltage will rise.
That is only true until the setting of the voltage regulator is met.
In the case of your car it is not a case of the voltage going too
high, only that at very low RPMs it can't meet the regulated voltage
under load.
With a 120v generator (actually alternator) the engine should maintain
a constant 3600 RPM to keep the 60 cycles constant. The throttle may
have to open or close to maintain the output power but the RPM should
stay the same.
If the RPMs did run away the voltage regulator should be decreasing
the excitation voltage to the rotor.
There are "inverter" style alternators that alter engine speed for the
load but the voltage fluxuating is still a function of the regulator.
I would be as concerned about the wrong frequency as the voltage.
Induction motors run at a multiple of the frequency, or at least they
try till they die.
He should really have this checked by a guy with a frequency counter
and a good meter before something blows up

Of course what you're saying is correct. I was just trying to explain
why the voltage could rise in the case of the throttle not being able
to close after the load is removed. In my car example, even if it
were fully into regulation, there will be some voltage flunctuation.
But it wasn't a very good analogy.

On the genset, if it's outside the regulator's capability to reduce
exitation enough, the described runaway could happen. Unlike the car,
the voltage regulator is designed to operate in an environment where
the motor will be maintaining a constant RPM regardless of load.
Since it's not, the regulator may not be able to compensate. It still
may be just a binding throttle or broken throttle return spring. It
definitely needs to be looked at before things escalate.

Any generator experts out there?
 

Agreed. I'm surprised he hasn't damaged something plugged into it
already. A testament to the power supplies in modern electronics no
doubt.

Jack Goff wrote:
On Thu, 13 Jul 2006 19:32:34 -0400, wrote:

On Thu, 13 Jul 2006 22:13:39 GMT, Jack Goff wrote:

Think of your car idling with the lights
on, the rev it up... the lights get brighter. Conversely, keeping the
same engine speed turn the headlights off, and the voltage will rise.
That is only true until the setting of the voltage regulator is met.
In the case of your car it is not a case of the voltage going too
high, only that at very low RPMs it can't meet the regulated voltage
under load.
With a 120v generator (actually alternator) the engine should maintain
a constant 3600 RPM to keep the 60 cycles constant. The throttle may
have to open or close to maintain the output power but the RPM should
stay the same.
If the RPMs did run away the voltage regulator should be decreasing
the excitation voltage to the rotor.
There are "inverter" style alternators that alter engine speed for the
load but the voltage fluxuating is still a function of the regulator.
I would be as concerned about the wrong frequency as the voltage.
Induction motors run at a multiple of the frequency, or at least they
try till they die.
He should really have this checked by a guy with a frequency counter
and a good meter before something blows up

Of course what you're saying is correct. I was just trying to explain
why the voltage could rise in the case of the throttle not being able
to close after the load is removed. In my car example, even if it
were fully into regulation, there will be some voltage flunctuation.
But it wasn't a very good analogy.

On the genset, if it's outside the regulator's capability to reduce
exitation enough, the described runaway could happen. Unlike the car,
the voltage regulator is designed to operate in an environment where
the motor will be maintaining a constant RPM regardless of load.
Since it's not, the regulator may not be able to compensate. It still
may be just a binding throttle or broken throttle return spring. It
definitely needs to be looked at before things escalate.

Any generator experts out there?
 

Many thanks for everyone's input!

I spend a couple of hours troubleshooting the genny on Saturday
morning, and found the culprit. The governor was working properly,
but wasn't returning the throttle to the idle position after the load
was removed. Adjusted the linkage from the governor to the throttle
body did the trick, in association with adjusting the governor to
attain the proper voltage.

I now need to throw a hertz meter on it to finalize the adjustement,
but it now purrs at 120V, settles in at 120V under load, and returns
to 120V when the load is removed.

Now if I can figure out how to keep my A/C from cycling so much, I'll
be in good shape!!

Any generator experts out there?
 

Yes, much of the wear on an ac compressor is from starting up.

wrote:
Many thanks for everyone's input!

I spend a couple of hours troubleshooting the genny on Saturday
morning, and found the culprit. The governor was working properly,
but wasn't returning the throttle to the idle position after the load
was removed. Adjusted the linkage from the governor to the throttle
body did the trick, in association with adjusting the governor to
attain the proper voltage.

I now need to throw a hertz meter on it to finalize the adjustement,
but it now purrs at 120V, settles in at 120V under load, and returns
to 120V when the load is removed.

Now if I can figure out how to keep my A/C from cycling so much, I'll
be in good shape!!

Any generator experts out there?
 

On Mon, 17 Jul 2006 12:39:10 -0400, wrote:

Now if I can figure out how to keep my A/C from cycling so much, I'll
be in good shape!!

Is the unit oversized? That is the first suspect in short cycling.
If it is sized right you can try more insulation, location of the
thermostat or better air flow. Is it creating one small cool spot near
the thermostat. That will cause short cycling. As the air spreads out
it calls for cooling again. A fan might help. If the whole area is
heating up quickly you need to reduce the heat load (insulation,
window covering etc). That will also save money. I assume this is a
boat so it is probably going to be hard to


It's a 12,000 BTU unit on a 30' Sea Ray, so I think it's sized
properly. It's the same BTU as the old unit, but the old unit seemed
to bring the temperature of the boat down faster.

During the day, it runs almost constantly, so under high heat load, it
works overtime bringing the cabin temperature down. The heat load is
pretty horrendous on these boats, especially here in Florida.

I went from the tried and true copper tube thermostat to a new digital
thermostat when I installed the new A/C, and I think the old
technology is more fitting for a boat, because I did not have cycling
problems with the old A/C system.

The problem is, the A/C will bring the cabin down to temperature, but
the temperature rises so quickly after the A/C cycles off, that it
cycles right back on again. I bought and installed the optional
remote temperature sensor, which I mounted in the return air duct, and
this helped a little bit, but did not cure the problem.

My next experiment will be to see if I can set the system so the fan
runs continuously, and does not cycle off with the compressor. I'm
thinking this may keep the air "mixed" better. I have two small fans
in the cabin, but they sound like a P-51 Mustang at takeoff, so
they're not something you can run at night!

Any generator experts out there?
 

If you could find a thermostat with different on and off temps that
might help. Then you set it to come on at 72 but not go off until 68.
I know that heater thromostats have anticipator circuits to compensate
for cycling but I don't think ac ones do.

wrote:
On Mon, 17 Jul 2006 12:39:10 -0400, wrote:

Now if I can figure out how to keep my A/C from cycling so much, I'll
be in good shape!!

Is the unit oversized? That is the first suspect in short cycling.
If it is sized right you can try more insulation, location of the
thermostat or better air flow. Is it creating one small cool spot near
the thermostat. That will cause short cycling. As the air spreads out
it calls for cooling again. A fan might help. If the whole area is
heating up quickly you need to reduce the heat load (insulation,
window covering etc). That will also save money. I assume this is a
boat so it is probably going to be hard to


It's a 12,000 BTU unit on a 30' Sea Ray, so I think it's sized
properly. It's the same BTU as the old unit, but the old unit seemed
to bring the temperature of the boat down faster.

During the day, it runs almost constantly, so under high heat load, it
works overtime bringing the cabin temperature down. The heat load is
pretty horrendous on these boats, especially here in Florida.

I went from the tried and true copper tube thermostat to a new digital
thermostat when I installed the new A/C, and I think the old
technology is more fitting for a boat, because I did not have cycling
problems with the old A/C system.

The problem is, the A/C will bring the cabin down to temperature, but
the temperature rises so quickly after the A/C cycles off, that it
cycles right back on again. I bought and installed the optional
remote temperature sensor, which I mounted in the return air duct, and
this helped a little bit, but did not cure the problem.

My next experiment will be to see if I can set the system so the fan
runs continuously, and does not cycle off with the compressor. I'm
thinking this may keep the air "mixed" better. I have two small fans
in the cabin, but they sound like a P-51 Mustang at takeoff, so
they're not something you can run at night!

Any generator experts out there?
 

On 18 Jul 2006 10:49:31 -0700, "jamesgangnc"
wrote:

If you could find a thermostat with different on and off temps that
might help. Then you set it to come on at 72 but not go off until 68.
I know that heater thromostats have anticipator circuits to compensate
for cycling but I don't think ac ones do.

This actually may be a function within the digital control, setting
the temp differential......I need to dig into the manual for the
controller.....