Output issues with MEP701A - Power outage issue.

[skinnyR1]

Hello,

We've been out without power for several days here in CT. I've been running my MEP701A. I have it wired for 120/240 split single phase. L0- Ground L1- HOT L2 - Hot. It has the jumper inside the unit. It is wired directly into a sub panel.

The issue is that it will not power my 3/4 hp well pump. On paper, it should, the pump demands 8 amps. If I isolate to only the well pump, it just does not have the power to turn it on, or so it seems. I turn on the well pump, the capacity meter jumps to 75% quickly and then the volts drop from 240 down to 50 or so on the generator. It falls on its face. It does not bog down rpm, just cuts power seemingly.

Any thoughts on what the issue inside the generator could be? It runs all my 120v stuff just fine wired just the same here into my subpanel. Turns on 3 fridges at once, coffee machine, lights. Runs a microwave no issue. It just seems like the generator fails or shuts off when pushed to levels over or near 75% capacity.

 

[Scoobyshep]

Sounds like it doesnt like the inrush of the pump. Is this a new problem or have you never run this pump on this generator before?

Sent from my SM-G973U using Tapatalk

 

[skinnyR1]

To add, I've put 15 hours on it over the past 3 days. Runs along no issue at 60hz. It is a low hour machine. I just don't know why it won't turn on a 240v well pump that probably surges or draws what I think is 8 amps max or something like 3000w.

 

[skinnyR1]

Sounds like it doesnt like the inrush of the pump. Is this a new problem or have you never run this pump on this generator before?

Sent from my SM-G973U using Tapatalk

I recently moved into this home, and haven't tested this machine at this house before this outage.

 

[Scoobyshep]

Check the start capacitor on the pump and see if its in tolerance. You may be able to replace it with a "hard start cap". The unfortunate truth may be the generator may be too small.

Sent from my SM-G973U using Tapatalk

 

[skinnyR1]

Check the start capacitor on the pump and see if its in tolerance. You may be able to replace it with a "hard start cap". The unfortunate truth may be the generator may be too small.

Sent from my SM-G973U using Tapatalk

This well pump is 35 years old and has no capacitor to start it. It runs; panel > on/off switch > Pressure tank switch > out to the well.

Is that my issue? There should be a capacitor to kick this thing off for gen power?

 

[Scoobyshep]

Some motors dont have them.

Sent from my SM-G973U using Tapatalk

 

[skinnyR1]

This is an older Franklin well pump, a 2 wire as its called, and they apparently don't have control boxes with start capacitors.

 

[Scoobyshep]

Well if you're up for trying it, you could install a soft start on the pump

Sent from my SM-G973U using Tapatalk

 

[nextalcupfan]

From what I've heard motors can have an in-rush current 2x or even 3x of the "Nominal" run rating.
For Example (keep in mind this is a tad extreme)

This A/C unit's LRA is 64A while the RLA is 12.8, that means the in-rush is 5x the run rating.

Now normally this isn't a big deal because the motor only draws this for a split-second. This is just a guess but your in-rush might be so high its tripping the short circuit protection.

I second what Scoobyshep says in that you should install a soft start.

 

[Light in the Dark]

As stated above, I think its the LRA thats beating up on this genset. Hopefully you get power back soon. We were out for about 42 hours, back on now thankfully.

 

[skinnyR1]

Ok. So it sounds like I have an old motor that has a huge inrush draw. Running amps are 8 amps but it could be drawing anywhere from 24 - 40 amps at start up?

What is the max amp output of a mep701a wired for 120v/240v split? On each leg, is it 16 amps max for a total of 32?

 

[Light in the Dark]

I couldnt find a data plate online to check (the manual I saw for the MEP-016B didnt show this). Doing some quick math though against the 3kw listed figure, I believe thats about 28A (@.8PF). So assuming that, you should have 28A in 120V, and 14A per leg in 240V.

 

[nextalcupfan]

The 701a is a 3kw generator (de-rated a bit from the military).
You asked 16A or 16A per leg, since 16A at 240 is 3840 Watts I'm going to go with 16A Total.
A 5kw MEP-802a is rated for 26A at 240V for comparison.

I think you only add the amperage together for 3 phase power.

 

[skinnyR1]

The 701a is a 3kw generator (de-rated a bit from the military).
You asked 16A or 16A per leg, since 16A at 240 is 3840 Watts I'm going to go with 16A Total.
A 5kw MEP-802a is rated for 26A at 240V for comparison.

Well, I guess this is my issue then. The generator is likely fine. If it only puts out 16 amps then it is likely the old well pump is just drawing too much.

 

[Scoobyshep]

Ok. So it sounds like I have an old motor that has a huge inrush draw. Running amps are 8 amps but it could be drawing anywhere from 24 - 40 amps at start up?

What is the max amp output of a mep701a wired for 120v/240v split? On each leg, is it 16 amps max for a total of 32?

Its 3000 watt at 240 volt (approx 12 amps). And yes its quite common to have a motor draw 300% FLA on startup. In the NEC there is an entire section for motor protection because of this.

Sent from my SM-G973U using Tapatalk

 

[dependable]

If the well pump is 35 years old, consider replacing at some point before it fails on you. That is a good run for one of these. Chances are new pump will not draw as much when starting. Is this an immersible pump or shallow well type?

I had my immersible(80 ft down) go out a couple years back, was kind of a pain to replace, and the plumbing stores were about to close for long weekend. Got it done but wish I could have done at leisure. Make sure you replace wires that go down there too, as insulation can fray on casing.

My old pump had external capacitor, the new one did not require, but is 1/4 more HP. Both of them starting make just a slight amp gauge swing on 002 and 802.

 

[skinnyR1]

If the well pump is 35 years old, consider replacing at some point before it fails on you. That is a good run for one of these. Chances are new pump will not draw as much when starting. Is this an immersible pump or shallow well type?

I had my immersible(80 ft down) go out a couple years back, was kind of a pain to replace, and the plumbing stores were about to close for long weekend. Got it done but wish I could have done at leisure. Make sure you replace wires that go down there too, as insulation can fray on casing.

My old pump had external capacitor, the new one did not require, but is 1/4 more HP. Both of them starting make just a slight amp gauge swing on 002 and 802.

Its a 3/4 hp 2 wire immersable. You bring up a good point though, that I should replace it due to age.

 

[uniquify]

Do you know how far down the pump is? I'm curious if the length of wire down to the pump is causing voltage drop.

 

[Scoobyshep]

Do you know how far down the pump is? I'm curious if the length of wire down to the pump is causing voltage drop.

nice thought, but they usually increase wire size if its that deepdown. not to mention it would have to be fairly deep to have enough drop to impact current draw significantly