Question for the generator guys

Brad Buchanan · Aug 8, 2014

Hey guys.

I just serviced my generator which had been
sitting for a year or so with carb problems.

It is an 11hp. 5500 watt Homelite with a Briggs
and Stratton engine.

I rebuilt the carb, fixed a stuck intake valve and
generally cleaned it up.

I fired it up and it is putting out 137 or so on
the 120 outlets and 247 on the 240 outlet. Should
this be ok with no load?

Also how do you determine whether it is putting
out 60 cycles? Do you adjust the voltage with the
rpms?

Thanks,

Brad

Dalex · Aug 8, 2014

Look at "Frequency Meter" on EBAY

JDemaris · Aug 8, 2014

Frequency meter is one way. Another is to just plug an AC powered analog electric clock into it for a little while and see if it keeps perfect time. If he cycles are not dead-on 60, the clock will run fast or slow. Those cheap little $15 Kill-O-Wat meters will plug into the outlet and give you a Hertz reading and voltage.

John T · Aug 8, 2014

I would expect that open circuit unloaded voltage to drop down once a real load was applied, give it a try n see what she does.

Cheap frequency meter on Flea Bay

John T

JMOR · Aug 8, 2014

(quoted from post at 20:17:11 08/08/14) Hey guys.

I just serviced my generator which had been
sitting for a year or so with carb problems.

It is an 11hp. 5500 watt Homelite with a Briggs
and Stratton engine.

I rebuilt the carb, fixed a stuck intake valve and
generally cleaned it up.

I fired it up and it is putting out 137 or so on
the 120 outlets and 247 on the 240 outlet. Should
this be ok with no load?

Also how do you determine whether it is putting
out 60 cycles? Do you adjust the voltage with the
rpms?

Thanks,

Brad

djust frequency with rpms. Those voltages look ok for no load. Two 120v incandescent lamps in series as shown make a good frequency comparator. When gen same as power line or very close brightness stays constant or slowly varying by difference in frequency. If far off, they will flash rapidly. Use two bulbs in series because when frequencies are not the same or absolutely in-phase, the pair of lamps see 240 volts.

souNdguy · Aug 8, 2014

test it loaded with lamps or heating elements...

Billy Shafer · Aug 8, 2014

That is normal under no load. The voltage will drop when the load comes in. I would get a kill a watt meter.To check the hertz.

Butch(OH) · Aug 8, 2014

You can get a Kill O Watt meter at Home Depot for less than $20 and it will tell you a lot about what is coming out of an outlet, watts, volts, frequency plus countless other things. Engine RPM alone is what controls frequency, Set it at 62-3 at no load and check the voltage, if its not too high than place a good load on it and it should settle in around 60 Htz. If the regulator is adjustable you then set the voltage where you want it. Lots of them are not adjustable. As the others have said either frequency or volts could be more important to your load, depends on what the load is and how far they are off from ideal. My home stand by set doesn"t have an adjustable regulator, I set the governor by frequency and the voltage will be anywhere from 128 to 112 depending on the load and how warm the head is.

David G · Aug 8, 2014

RPM determines frequency, voltage regulator determines voltage. Every governor has a little droop so you need to over speed a little with no load.

jeffcat · Aug 8, 2014

Your diagram is correct but you can buy 220 volt bulbs and it will make it a little easier. I have a Fluke meter that does cycles. I have both generators set at a touch over 60. One is 3000 and the other is 8000 watt. Big time power. If you have NEW electrical equipment you MUST have correct cycles. Try blowing up a $200.oo circut board in your new 95% gas heater!

Geo-TH,In · Aug 9, 2014

Brad,
I have a champion 3500 w RV generator, electric start, built in hour, volt and frequency meter. IMHO, that was worth the extra $160 it cost.

As for kw meters. I purchased one off ebay to measure powerfactor. It measured everything else too. Did a good job measuring powerfactor. Frequency was another story. I pluged it in the house, 60 hz. Plugged it to new genny 60 HZ. Frequency meter on genny said 65 hz. So I slowed genny down from 65 to 60. kw meter still said 60 hz. So hope you get a better kw meter than the one I got.

The best way would be to have a good dual trace scope, compare the power company to the genny. Kinda of miss having a good scope, like the one I had at work.

I really don't think the frequency is really that critical. Look at motors and transformers, some say 50 to 60 HZ.

Been scratching my head trying to come up with a way to design a simple device to compair two frequencies without using an expensive scope.

Perhaps our resident rusty electrical engineer could design something.

George

Geo-TH,In · Aug 9, 2014

Jessie,
Interesting idea, but I'm a little chicken. If you
got your genny at 61 hz and the power company were
60 hz, would you could see the bulbs go on and off
1 time a second?

You better make sure your house is wired correctly
and you use a 3 prong plug. I've seen where some
IDIOT wired power to the neutral side of an
outlet.

Is it possible you could get the neutral side of
your genny connected to the hot side from the
power company? Or is the neutral side of a genny
isolated?

I have two gennies and never thought to check.
Been thinking of connecting a gfci to genny and
seeing if I connected a light bulb to the power
side and connected the other side of bulb to a
grounding rod, if it would trip the gfci. Just
going to have to do that experiment when I get
bored. That would definately be a good test to see
if the genny is isolated from ground.

Nice chat Jessie.
George

Billy Shafer · Aug 9, 2014

Except on generators that don't have regulators.

JMOR · Aug 9, 2014

(quoted from post at 08:44:56 08/09/14) Jessie,
Interesting idea, but I'm a little chicken. If you
got your genny at 61 hz and the power company were
60 hz, would you could see the bulbs go on and off
1 time a second?

You better make sure your house is wired correctly
and you use a 3 prong plug. I've seen where some
IDIOT wired power to the neutral side of an
outlet.

Is it possible you could get the neutral side of
your genny connected to the hot side from the
power company? Or is the neutral side of a genny
isolated?

I have two gennies and never thought to check.
Been thinking of connecting a gfci to genny and
seeing if I connected a light bulb to the power
side and connected the other side of bulb to a
grounding rod, if it would trip the gfci. Just
going to have to do that experiment when I get
bored. That would definately be a good test to see
if the genny is isolated from ground.

Nice chat Jessie.
George

es, one time per second. BTDT. With little portable generators, they are basically like a bird on a power line so, neutral/line doesn't really matter as long as you don't get you body into the circuit.

Brad Buchanan · Aug 9, 2014

Thanks for all the helpful replies.

I always learn something when I am on this board.

Brad

Geo-TH,In · Aug 9, 2014

What is you touch the metal on genny? Is the genny
isolated from metal frame? If it, then why does
some RV people think they need to have a grounding
rod. OH MY, I REALLY DIDN'T ASKING THAT QUESTION.
Ground and neutral seems to push some buttons.
Only good reason I could think of for grounding an
RV when using a genny is lightning.

Cas · Aug 9, 2014

I had the same generator and it did the same thing yours is doing. It does not take much of a load to bring the voltage down.
The thing I did not like about it is that it runs wide open. Made a lot noise. I put it outside and closed the garage door Worked good and used it as a whole house generator and never had a problem. Overloaded it quite a bit. Ran ererything when every needed including 1 hp submerisble.
Remember it is a little generator and not a Caterpillar 125 KV generator.

ss55 · Aug 9, 2014

"If you got your genny at 61 hz and the power company were 60 hz, would you could see the bulbs go on and off 1 time a second?"

George, that's a good one!

I'm not sure it would be safe to have a generator connected to the grid unless it had the proper safeguards and you were setup to sell power to the grid.

If you had your generator connected to the grid without the proper safeguards, some politician could use the power from your generator to reverse all the hydroelectric turbines in Hoover Dam and refill Lake Mead from the Gulf of California using your power! Your generator would then use a lot more fuel than normal.

guido · Aug 9, 2014

Hello Brad Buchanan,

You can use a electric clock with a swept seconds hand and a stop watch. The voltage will vary with load, so you will need to check it while under load. High end gen set have isochronous(zero droop) governor. That keeps the output at 60 Hz,

Guido.

Geo-TH,In · Aug 9, 2014

Jessie,
I checked, my genny is totally isolated from the metal case. I guess when I get bored, I'll make your device. Be interesting experiment to set the one genny I have with built in frequency meter. Set it as close to 60 hz, say 60.1 and watch the bulbs take about 10 seconds to go bright and dim. It will be like tuning a musical instrument and listening for the beat frequency. Also be a way to compair the frequency meter to the power company.
George

John T · Aug 9, 2014

On many off the shelf small gensets the Neutral would be bonded to the metal case frame and no connection to a "Grounding Electrode" is required if you feed cord and plug connected tools via onboard mounted receptacles.

If you want to use the genny as emergency 120/240 volt backup to feed your home panel via a transfer switch and you want to use ONLY a 2 pole (2 hots) transfer switch, the gennys Neutral would be disconnected from the frame,,,,,,,,the gennys Neutral would bond to the utility Neutral (often inside the transfer switch),,,,,,,,,The Equipment Grounding Conductor from the homes panel would run out and bond to the gennys frame,,,,,,,,In this situation the genny is NOT configured as a Separately Derived Source.

If youre simply just using the genny to feed your home period i.e. no transfer switches etc., the Neutral would remain tied to the case, the Neutral would be tied to a "Grounding Electrode" (such as a driven rod) and this configuration is a Separately Derived Source similar to a utility transformer which has its Neutral tied to the can plus to a bare No 4 copper grounding electrode conductor ran down the pole to a Grounding Electrode (driven rod)

John T

IH2444 · Aug 9, 2014

You can also use a tach to read engine speed. On most generators 3600 RPM = 60 HZ output.

big fred · Aug 10, 2014

Feed both frequencies into speakers. Synchronize them by ear. Should be able to get within 1 hz easily, even if you're tone deaf, since all you're listening for is the beating sound..

buickanddeere · Aug 10, 2014

120V into a 4 ohm speaker is going to make some kind of sound.

Geo-TH,In · Aug 10, 2014

I think it's might be more like 240vac into 4
ohm's. When one genny is producing a + peak, the
other genny is producing a negative trough, I
think the two waves will cancel each out producing
0 vac. Will the two waves add together, 240 vac
when both are in phase? Or do I have it backwards?

I have an idea. In my younger days, I and a friend
both had honda 305 dreams. If we were riding side
by side, going exactly the same speed, the exhaust
from the two engines would produce a beat
frequency, the sum and difference of the exhaust
pulses. The closer the rpm's got, the more in tune
the sound. But that only says the rpm's are the
same, producing the same frequency. Doesn't
confirm both gennies are producing 60 hz. Would
have to do like Jessie posted using the power
company as the standard 60 hz and compare a genny
at a time to the power company.

big fred · Aug 10, 2014

That's pretty much what I was driving at. I synch the twin engines on my boat like that.

mkirsch · Aug 11, 2014

Get yourself a "Kill-A-Watt" meter. It plugs into a normal outlet and gives you Volts, and Hz. Plug something into it and it also gives you Amps, Watts, and Kilowatt-Hours of whatever is plugged in.

I keep one in my camper to monitor the quality of the electricity coming from the generator.

Question for the generator guys

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Similar threads