New Install Hz readings

[securitymedic]

Hi Kelly,

I just completed my new 16KW model OF9145 install today and I have some concerns on the freq readings and would like your input. I am running it on natural gas.

Natural gas readings:
6.8" WC static
6.2" WC running no load
6.1" WC running at 30 amp load (sum of both legs).

Engine RPM: 3480
No load voltage: 246.5 to 249.2
30 amp load voltage: 249.7 to 253.1
30 amp load Hz: 58.2 to 60

It seemed to consistently run at 58.2 Hz during the 30 amp load test but I did see an occasional 60 and 60.1 reading now and then.

With the book saying it should be "greater than 60Hz", I'd like your thoughts.

I recommend to other owners buying the Tiny-Tach. 5 minute install and you get the hour meter too!! Works great.

Thanks!!

Jim

[Dick Chimney]

Hi Jim,

Thanks to your posting, I checked my 5241(10KW/9KW) model today.

At idle with no load, tiny tach reading is aroud 3100~3200 rpm, well below 3600 rpm.
According to the manuel, I should stop. I did not and put the load on the genset one breaker at a time until the total 10 circuits are on. The engine run smoothly and I checked the reading again, it read around 3500 rpm. Since the genset seems to power my house without taking a breath, I would assume it is OK. Thanks.

By the way, where is Kelly? Is he taking a vacation?:)

Dick, the quick drawer.

[Dick Chimney]

Oh, Dick!

What an egg head you are! The manual never tells you to measure engine speed using the tiny tech and take it as your electric output frequency. You are supposed to measure the frequency of your electric output using a frequency meter at the transfer switch. You are misleading the public. Please apologize.

The following are Dick?s speculations. Please do not take it too seriously:
If the engine rpm should be the frequency of output electricity, then my engine would have a constant output of 18 hp @ 3600 rpm. By the Kelly?s law of physic, my genset would have a constant output of 9kw of electricity regardless of the load demand. It simply does not make sense because it would waste a lot of unused electricity. Therefore, the engine should be allowed to vary its speed to accommodate the power needs. Then what about the frequency? Well, if we have ?voltage? regulator to regulate the voltage output, why not ?Frequency? be regulated by a ?Frequency? regulator. Guess what! I did find similar products called ?Frequency converter? on the internet. They are capable of changing the input frequency ranging from 50 Hz ~ 63 Hz to an output frequency of 60 Hz. Guardian did mention the ?Voltage Regulator?, but no words found about ?Frequency Converter?. However, there must be something similar in the power board. Maybe Kelly can tell us in more detail.;)
Thanks

Dick, the quick drawer

[Kelly Myers]

Hi! We are moving offices, so I haven't had much time to check the forums here. Anyways, I see we are trying to check output on the new model.

First thing, there are no adjustments to the output frequency. We can still alter the voltage via the voltage regulator though. 99.9% of VR's are properly tuned from the factory.

Now, to the Frequency (hz). For some reason, the 16kw is designed to yield 59.6HZ. This is not a problem for any electronics or motors. It is close enough where you will not notice any difference then when you are on Utility power.

I am guessing your low readings are from the lack of a tuned, or true-RMS multimeter. If you try tuning a generator in with a non RMS meter, you may be doing more harm then good.

Tiny Tach's ARE NOT ACCURATE ON RPM'S!!!!! They serve as an estimate. They are however perfect at keeping track of time, which is very important.

If you want to find out exactly how fast the engine is going, Get ahold of a Digital multimeter capable of measuring HZ. Put one lead on N1, one lead on N2, and multiply the frequency by 60. You will find the engines are running around 3,570 RPM's.

I am at a loss as to why Generac didn't tune the governor's in to 60.00 even, but there must be a reason for it. And again, it will not have any ill-effects except for devices that are designed to function of 100% clean power. In the home, this would apply to lower end UPS systems, and that is about all.

Plasma TV's, LCD TV's, Computers, AC units, furnaces, and all other electronics in your house will not see this as an issue.

[securitymedic]

Kelly and Dick:

Thanks for both replies, I realize now the Tiny Tack is not the way to measure accurate RPM. I bought it for the run time hour metering anyway, so no big deal. As to the Hz readings, I was not using a RMS frequency meter as you suspected (too many $$$ for a good one!), I have a Fluke 337 clamp meter which is not as accurate, but gets pretty close.

I'm happy with the output and do not believe I have anything to worry about. You are also correct about the UPS being sensitive, my $85.00 PC UPS clicks continuously while running on generated power. I have used other portable generators in the past and they all bothered that darn UPS. It is annoying though.

What a beautiful generator though, and now I'm fully automatic too!

PS - I went a step further on my install and added a Fire Dept emergency generator disconnect beside my meter base, and had a placard engraved and put it on the meter base saying: "THIS RESIDENCE HAS A FULLY AUTOMATIC NATURAL GAS GENERATOR AND AUTO SENSING TRANSFER SWITCH WHICH
WILL START AND POWER THE RESIDENCE IF PRIMARY POWER IS LOST. USE THE GENERATOR DISCONNECT SWITCH LOCATED TO THE RIGHT, TO DISCONNECT THE GENERATOR POWER."
Don't want to endanger unsuspecting firefighters.

Thanks again,

Jim

[Kelly Myers]

PS - I went a step further on my install and added a Fire Dept emergency generator disconnect beside my meter base, and had a placard engraved and put it on the meter base saying: "THIS RESIDENCE HAS A FULLY AUTOMATIC NATURAL GAS GENERATOR AND AUTO SENSING TRANSFER SWITCH WHICH
WILL START AND POWER THE RESIDENCE IF PRIMARY POWER IS LOST. USE THE GENERATOR DISCONNECT SWITCH LOCATED TO THE RIGHT, TO DISCONNECT THE GENERATOR POWER."
Don't want to endanger unsuspecting firefighters.

Thanks again,

Jim

That is a really good idea! On all of our installs we put a sticker that says "This Residence equipped with an automatic standby generatore" on all the meter cans.

UPS systems and generators usually don't work too well together. Unless you're going with a digitally controlled generator. The problem with lower end UPS systems is they normally look for a 2% change in voltage then resort to battery backup.

A basic explanation, without all the tech garble:

Power outage - UPS on battery
Generator fires - makes clean power
Transfer to generator
UPS - Sees clean power, starts to recharge battery
UPS - The battery charge puts a new load on generator
Generators - bogs (for sake of statement) 3% before the governor controls it back to "clean" power
UPS - Sees drop in voltage, Resorts to battery
Generator - Recovers and makes clean power
UPS - Sees clean power, starts to recharge battery.

Its a neverending loop.. Causing low end UPS systems to cycle on/off.

You can purchase a Line-Interactive or ONLINE UPS system that cleans the power, and it will work fine. Normally these have a 7% tolerance in the ability to clean power, without cycling to the battery

I did a big write up on this for a customer who purchased a couple hundred generators a while back, including detailed tech data. I'll see if I can find it.

[securitymedic]

Thanks Kelly for the dissected UPS explanation, it makes sense of all the racket it makes. I'll look forward to your tech data if you come across it.
I'll get some pics for you too on the disconnect and placards.

[Dick Chimney]

Hi, Jim and Kelly

Thank you for all the postings.:)

I was so convinced by the readings on my Tiny Tach meter that I conjured up a ?variable speed? generator, which is obviously not the case for air-cooled Guardian generators. To support my imagination, I even twisted the interpretation on engine performance spec.:confused: I want to clarify here: For 5241 model, 18hp@3600 rpm for engine GT-540 should not be interpreted as ?when the engine speed is 3600 rpm, the only output is 18 hp?. 18 hp is the maximum output but not the only output at 3600 rpm.:eek: It is like riding a bicycle. When you are going up a ramp, you can still keep the bike at the same speed as that on a level as long as you increase the muscle force for every stroke on the pedal. Therefore, a governor is used to adjust the ?muscle? strength at every power stroke of the engine to accommodate the utility load demand while keeping engine spin at 3600 rpm.:D

I bought a True RMS multimeter on line last night and I wanted to use it to check the output voltage and frequency of my generator at the transfer switch. I hope that I can get a good reading as Jim?s and declare that the Tiny Tach is too easy to install to be accurate in terms of engine rpm readings.:(

It is obvious that Kelly has a lot to share with us like the explanation of why generators do not work well with low-end UPS. Members of this forum should ask him more questions so that he would tell us more. Thanks.:)

Dick, the quick drawer.

[wwarren]

The problem with lower end UPS systems is they normally look for a 2% change in voltage then resort to battery backup. [...] You can purchase a Line-Interactive or ONLINE UPS system that cleans the power, and it will work fine. Normally these have a 7% tolerance in the ability to clean power, without cycling to the battery

For what its worth, APC and their generic brand Conext UPS come with configuration software called "Shutdown Manager" that lets you customize their performance. Noisy power sensitivity has high, medium (default) or low settings. Voltage kick-in range can be adjusted from a low of 94V to high of142V (98V/139V default).

After you make your settings, the battery remembers them and you can shutdown the configuration software, or even move the battery to a non-computer load. I bought two 950VA Conext models from CompUSA last October for $89 each and use one at my computer and one at my Tivo.

Walter