Question for electricians

[John_Mc]

What do the last 3 have to do with the OP’S Question

Topic drift is a way of life on TBN.

 

[grsthegreat]

it has nothing to do with THD for ups's hating the generator, its because they expect the hertz to stay within .5hz, non inverter models tend to drift around 1 to 2 hz depending on load, this is what causes them to trip over and over.

computers can give 2 sh*ts about thd quality they uses switching power supplies.

Even my generac standby has the frequency float more than 0.5hz, and my ups devices can care less. But i honestly have no idea what my UPS devices are monitoring that affects their operation. But im sure generators that output truer power with lower THD will also have better electronics and such ( like voltage regulators) which all contribute to better operation.

No 2 pole or 4 pole generator will give absolutely pure 60 hz. Inverter units are way better at this.

 

[LittleBill21]

Even my generac standby has the frequency float more than 0.5hz, and my ups devices can care less. But i honestly have no idea what my UPS devices are monitoring that affects their operation. But im sure generators that output truer power with lower THD will also have better electronics and such ( like voltage regulators) which all contribute to better operation.

No 2 pole or 4 pole generator will give absolutely pure 60 hz. Inverter units are way better at this.

is the generac mechanical or electronic governor? I never played with a generac, inverter units don't move off 60hz.

I have 13 ups's, i have only seen inverter models not cause grief. That said this is based on cheap consumer ups's they make ups's that are generator tolerant in commercial settings. some of the apc units have sensitivity settings as well.

 

[Jimbo913]

Topic drift is a way of life on TBN.

Can you wire in something like this so you can monitor from inside?

 

[grsthegreat]

is the generac mechanical or electronic governor? I never played with a generac, inverter units don't move off 60hz.

I have 13 ups's, i have only seen inverter models not cause grief. That said this is based on cheap consumer ups's they make ups's that are generator tolerant in commercial settings. some of the apc units have sensitivity settings as well.

Larger standbys use electronic stepper motor for control, but still not rock steady on frequency.

 

[rontaki]

The THD issue has to do with excess heat being created in electronic parts, due to the non-sinusoidal waveform, I have read. It all feels the same to me when it bites.

 

[John_Mc]

The THD issue has to do with excess heat being created in electronic parts, due to the non-sinusoidal waveform, I have read. It all feels the same to me when it bites.

From what I've heard, that's at least part of the issue. Excess heat can shorten the life of electronic components. If it gets hot enough, it can fry them in short order, but temperatures short of that can still shorten the life, and from waht I understand, it can be a cumulative effect: repeated slight overheating will eventually kill some electronics.

The other issue is that some electronics simply will not function if the power is too "dirty". I don't know if this is a safety thing that is built in to protect them or if the poor power just causes a malfunction. I've run in to two heating systems that had issues like this. One simply would not function when connected to a generator with known dirty power (the generator rating, when we were eventually able to find it was 24% THD). The other control system would not start up on the owner's generator (don't recall the brand of generator or it's THD), but it was OK if it was started up on cleaner power and then switched over to a generator. Both systems ran fine on my generator. Both owners eventually switched to a better generator so they could run their heating systems with it in an emergency.

 

[WinterDeere]

it can be a cumulative effect: repeated slight overheating will eventually kill some electronics.

See Arrhenius plots of failure due to electromigration, if you're interested in this. Although not really even the primary failure mechanism in most circuits, this is most often used to predict their MTTF (mean time to failure). And yes, it's a direct 1/log(T) relation to operating junction temperature of the transistors.

In most classic electronics, it's actually the electrolytic (or dreaded tantalum) capacitors that fail, way before the transistors. But new ceramics have become available over the last few decades that have allowed the elimination of more and more electrolytic capacitors.

The other issue is that some electronics simply will not function if the power is too "dirty". I don't know if this is a safety thing that is built in to protect them or if the poor power just causes a malfunction.

I would expect that if THD is claimed as a problem, it's because with high THD there is much energy contained in frequency components other than 60 Hz. A circuit designed to operate on 60 Hz is usually going to have large filter components designed to cut out lower frequencies (transients) and higher frequencies (intermodulations / spurs, and harmonics), and the more power that the generator puts into these non-60 Hz components, the more energy these filter circuits must dissipate = heat. Of course, these are usually just made of cheap capacitors and inductors, even transients can be removed downstream of DC conversion by a few large capacitors.

In absence of these filter circuits, on the power supply portion of the electronic device, then you need to consider how susceptible the downstream circuitry is to these artifacts. Again there, things like transients and spurs bleeding thru can cause additional heating or unwanted behavior.

 

[Hoho223]

Same. I run the whole house on a 7 kW portable, including 3/4 hp well pump, by shutting off breakers to things like AC compressors, air compressor, pool heater, etc.

The primary trouble I have with the portables is power quality, as my Lutron low-volt lighting goes absolutely nuts (flickering wildly), and my small fleet of computer UPS's constantly squawk about voltage or frequency variations.

For those switching from portable to standby, did you notice a big difference in power quality, and how things like UPS's respond to it?

I'm not overly taxing the portable, voltage is not dropping because of overload, so that's not the trouble here. I honestly wonder if the frequency variation may be causing more trouble than the voltage variation, as the regulation seems reasonably good.

I should mention that I had to have the stator rewound. I never had any flickering lights, we watched TV, the hot tub was shut off. Not sure of well pump size but the well is 287 feet deep but was not home when pump was placed…so at least a 3/4 hp pump.

 

[WinterDeere]

…so at least a 3/4 hp pump.

Probably even bigger than that, at your depth. I think they usually recommend over 1.5 hp when going that deep, and usually more than that if you want reasonable pressure and flow rate.

I'm no expert, just going off the graphs I see online. But I think 2hp delivers about 13 gpm at 400 feet, and lands pretty neatly in the sweet spot for best efficiency.