MEP802 on the House. What's going on here...

[G744]

Most single-phase motors pull around 600% of running current to get up to speed.

Unless it is an inverter-type genset, the 60Hz freq (speed) goes down and things go awry.

The problem with small gensets is that kind of demand has a lower load impedance than the alternator, and can't provide enough energy above a power factor of .8...

IOW, you need a bigger gen or less motor loads.

 

[rickf]

I'll have a look tomorrow and see if I can find a data plate on it.

That plate will also list the running amps and may also list the starting amps if it is a newer unit.

 

[sjc]

It seems like it could be a wiring issue to me ... as rickf has stated, you need to check voltages on your house switchboard ... this will rule out any wiring issues between the generator and the house/appliances

 

[98G]

I'll have a look tomorrow and see if I can find a data plate on it.

 

[98G]

Most single-phase motors pull around 600% of running current to get up to speed.

Unless it is an inverter-type genset, the 60Hz freq (speed) goes down and things go awry.

The problem with small gensets is that kind of demand has a lower load impedance than the alternator, and can't provide enough energy above a power factor of .8...

IOW, you need a bigger gen or less motor loads.

I've been using the twin to the one you got from me. No worries with capacity there.

But I grabbed several of the 802's and wanted to see just how much load balancing would be needed.

 

[Scoobyshep]

That's just the condenser fan. The compressor is the more significant thing to look at. There should be a sticker on the outside of the unit with the overall assembly rating

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[98G]

That's just the condenser fan. The compressor is the more significant thing to look at. There should be a sticker on the outside of the unit with the overall assembly rating

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Yeah, someone saw fit to remove it. I found a sticky square area .

I'm going with the idea that the AC is just way too much for the genset. I just expected a different failure modality. I've overloaded an 802 with my plasma cutter and it simply fell on its face.

 

[nextalcupfan]

I wouldn't take that as the final answer, based on what you're describing it feels like something else is going on.
I've overloaded my 803a 2 times on my house and it was painfully obvious it was in distress, engine slowing down, all lights dimming in the house, pouring black smoke.
I suggest you keep investigating, perhaps somewhere in the transfer switch you're losing a leg?
Like someone tightened a screw over some wire insulation instead of bare wire.
That could in theory allow current and voltage to pass at low load but during the inrush of the AC it loses connection.

I also seem to recall a YouTube video showing an 802a starting a 2.5 ton AC.

 

[Ray70]

I 2nd that notion! Something doesn't sound right to me.
I'd first verify your gages are reading accurately when under heavy load.
There's no reason your other items should be running "slow" if the generator is operating normally.
Something else must be going on.

 

[Farmitall]

An electric motor cannot tell the difference between being under voltage or "mechanically over loaded". If motors are running slow, they are under voltaged and the line voltage should be verified by an accurate meter, not the meter on the generator.

 

[Scoobyshep]

An electric motor cannot tell the difference between being under voltage or "mechanically over loaded". If motors are running slow, they are under voltaged and the line voltage should be verified by an accurate meter, not the meter on the generator.

Frequency too.

There are 3 ways to change the speed of an electric motor. Change the number of poles (think old mechanical fan switches)

Alter voltage (which also alters current so motor damaging)

Alter Frequency

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[98G]

Fluke meter and kill a watt are on the list. When I get them I'll run it again and update this thread with more and better data.

It may be a bit as I've got multiple demands and I'm getting pulled several directions at once.

Thank you everyone for the enlightenment.

 

[Guyfang]

When you are dealing with AC, RPM=Hertz=frequency. If AC things are running slower. You need to check freq, at the outlet servicing the device.

 

[sjc]

When you are dealing with AC, RPM=Hertz=frequency. If AC things are running slower. You need to check freq, at the outlet servicing the device.

synchronous drives/motors, yes ... but in the case of asynchronous induction motors (most motors in a household), lowering voltage will change the speed as the torque produced is voltage dependent ... lower voltage = more slip = lower speed

 

[Evvy Fesler]

synchronous drives/motors, yes ... but in the case of asynchronous induction motors (most motors in a household), lowering voltage will change the speed as the torque produced is voltage dependent ... lower voltage = more slip = lower speed

I'm surprised by the microwave though. It's likely has low voltage motors and perhaps they are DC.

 

[Scoobyshep]

I'm surprised by the microwave though. It's likely has low voltage motors and perhaps they are DC.

Youd be amazed at how bad line power can manifest

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[sjc]

I'm surprised by the microwave though. It's likely has low voltage motors and perhaps they are DC.

in my experience, microwave turntable motors are AC or low voltage DC (poorly regulated, so lower AC voltage probably manifests itself as a lower DC voltage to the drive) or sometimes even synchronous AC ... it might just be a perceived slowdown but in reality be the light being dimmer and the output of the magnetron being lower with a lower AC supply ... in any case, as everyone has said ... test at the point of use, not the source

 

[2Pbfeet]

I think that you just need a little more of the label on the second picture to get a model and serial number. Most data plates aren't easily removable, but it might be behind the service cover. Trane normally has them on the outside, and I can not think of a legitimate reason to remove it. With the model number, you can look up the specifications online. The LRA (Locked Rotor Amps) are in the range of 105-134A from what I can tell, so probably well beyond what even your beefy 802A is up to.

https://www.americancoolingandheating.com/wp-content/uploads/2012/06/22-1842-07.pdf

I would also double check the hot to neutral values for circuits on different hots, and check the ground and neutral paths, especially at the transfer switch and main panel, but I think that this is a case of large overload.

All the best,

2Pbfeet