802a, Hertz dropping under load.

[biz]

when i warm up the unit i set it at 60 hz. under small loads it doesn't drop much. sometimes .5 hz. but when i apply larger loads like 6500 or so it drops 4-5. is that normal or is the unit supposed to hold 60, or whatever its set for, no matter the load?

 

[DieselAddict]

4-5hz is maybe a little more than expected BUT 6.5kw is pretty much maxed out on an 802. If there is residue in the exhaust from wetstacking or if your air filter is not clean you'll loose control of the load and stall.

Normally you would set the frequency for about 61.5 and it would droop down to about 59 when fully loaded.

I would start by examining all the governor linkages and make sure everything moves freely. Some lube never hurts.

 

[biz]

would you normally set the frequency that high while running your home?

 

[DieselAddict]

I personally set mine to 61hz unloaded.

 

[NormB]

6.5 kW should be SURGE draw, not continuous load, and yes, a drop in Hz like that sounds normal under the conditions.

I'm relatively new to this kind of generator myself - bought last June - but I regularly set it for 61-2 Hz (approximately, for parallax error reading on the instrument and inbuilt variances in scale readings) and under loads it may drop to 59.

Safe to run? I used a step-down transformer when I lived in Germany and my cassette player ran slower than normal due to the 50 vs 60 Hz difference in line voltage. Didn't hurt anything, but since the motor was linked to the Hz "signal", it made Sting on my Police tapes sound like Perry Como.

Maybe Guyfang will chime in here.

 

[Triple Jim]

would you normally set the frequency that high while running your home?

In the world of electrical stuff, 5 or 10 percent is not normally a big deal. Running at 62 Hz is only 3-1/3 percent high. The only thing that will care is an old fashioned electric clock, because it'll be 2 minutes ahead after an hour of running.

 

[Dwnorton1]

I, too, run my at 61.5hz unloaded. Might drop to 59hz when loaded. I verified my analog gauge with my Fluke 787. I would verify your gauge as well. If you start with Hertz a little high it seems to help with droop. Might be power band of engine. If I don't go above like TM recommends mine will drop just not sure how much. Tone changes in sound of my engine from 58hz to the 61.5 seems to run better at higher rpm.

 

[Daybreak]

Howdy,
I would not worry so much about the unloaded Hz. I would tweak your settings to see what your average normal load is. After you see what your average load is, I would then adjust it to 60Hz. In other words, you have it powering your house. You have a few lights on and refrigerator running, saw your current draw is 3000 watts, showing about 75% on the gauge, set you Hz here to 60 and then totally unload you system and look at what you unloaded Hz is. The MEP-802A has a mechanical linkage. That is why you physically change the speed of the engine to set you Hz.

In the United States, electrical items are given a UL rating. Manufacturers make things to withstand a variable of 7-10% from normal to still operate. UL wants it to be a variance of 5%. All and all, things like to be at 240volts and 60Hz. That is also why it is wise to have a battery backup on big TV's and computers. Electronics really like to have what is known as clean power.

 

[biz]

6.5 kW should be SURGE draw, not continuous load, and yes, a drop in Hz like that sounds normal under the conditions.

I'm relatively new to this kind of generator myself - bought last June - but I regularly set it for 61-2 Hz (approximately, for parallax error reading on the instrument and inbuilt variances in scale readings) and under loads it may drop to 59.

Safe to run? I used a step-down transformer when I lived in Germany and my cassette player ran slower than normal due to the 50 vs 60 Hz difference in line voltage. Didn't hurt anything, but since the motor was linked to the Hz "signal", it made Sting on my Police tapes sound like Perry Como.

Maybe Guyfang will chime in here.

correct me if im wrong but i thought i read here that 6500 is max load for the 802 and that it could sustain it. mine was running smooth under 6700 watt load and not bogging down other than the 4-5 hertz drop i mentioned earlier. it didnt stall or anything.

 

[JRM]

Even my 803 drops to 58 or so as I approach 10kw

 

[Triple Jim]

Electronics really like to have what is known as clean power.

Clean power without spikes maybe, but they're normally very insensitive to voltage and frequency errors. You can check the labels, but a typical one might say it's OK with 90-130 volts and 50-60 Hz. Some of my electronics are OK with 100-250 volts! My inverter welder automatically adapts to anything from 120v single phase to 240 three phase, depending on what you connect it to. Back in the old days of square wave inverters, I used to run TVs, VCRs, and computers on them and they never complained.

 

[csheath]

Not sure about the 802 but the 803 manual outlines the steps to adjust for frequency droop. That said my 803 drops when loaded and making the outlined adjustment made little to no difference. I only turned the adjuster a couple of turns total but quit when I saw little to no change. If I set my no load hertz to 61 it gets down to 58.8 at full load so mine is within specs.

 

[Guyfang]

Its normal. Some sets a little less, some a tad more. Not to worry. Keep in mind, a house is a load that will vary up and down anyway, as things get turned on and off. So a few hertz won't matter much if at all.

Our bigger gen sets, had a bigger drop under load, until we went to electric governors AND actuators. Before that, we had electric governors, and Hydraulic actuators. Talk about unstable. And they were suposed to be precise gen sets!! No, don't worry about it. Its when your engine slowly dies out that its time to worry.

 

[biz]

Its normal. Some sets a little less, some a tad more. Not to worry. Keep in mind, a house is a load that will vary up and down anyway, as things get turned on and off. So a few hertz won't matter much if at all.

Our bigger gen sets, had a bigger drop under load, until we went to electric governors AND actuators. Before that, we had electric governors, and Hydraulic actuators. Talk about unstable. And they were suposed to be precise gen sets!! No, don't worry about it. Its when your engine slowly dies out that its time to worry.

Thanks! no offense to anyone else but i was really hoping you would chime in.

 

[biz]

ok dont laugh at me...

So i never really paid much attention to the the lines and numbers on the frequency gauge other than just having the needle at 60. So when i ran my unit under that 6800 load and it dropped 4-5 hertz(was 4-5 lines), it was actually only 2-2.5 hertz.

So i guess my unit is running really well lol.

 

[jimbo913]

Been there myself

 

[Triple Jim]

I recently did that with a tire pressure gauge that I thought had marks every 2 psi like another one I have. I had to go back are re-fill about 8 tires when I figured it out.

 

[Guyfang]

I am dyslexic. This sort of thing comes natural to me. I always check EVERYTHING 4-5 times. Work myself up into a tissy, and for the most part am right the first time. BUT, since I don't trust myself, check it again and again.

 

[jimbo913]

When I made this mistake, it was the first gauge I recall encountering with .5 increments. Honest mistake when I typically deal with lines meaning 1 or 2. The good thing is that it is a lesson you do not easily forget.

 

[Guyfang]

You got that right!