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  #1  
Old 03-16-2016, 08:09 AM
steveb steveb is offline
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Default Different Gas Generators power well pump strangely

Hello BHMers!

Thanks for looking at this question. I hope your wisdom will clear this up for me.

I have a very deep well at 78 meters. It is powered by a 220v, 8–12amp, 50hz pump.

When I use an old Honda EW 171 welder generator (with the specs of AC Output of 220v, 3.0 kVA, 60 Hz) to power the pump, when I turn on the control box for the pump, the generator will rev up a bit to take the initial power surge/drain, then quickly settle into a smooth running...but, the pump only brings up about 10 liters a minute. Also, I need to set the control box at 11 amps, or else the control box auto-shuts off after a minute or so of running.

If I use an Einhell BT-PG 3100/1 generator (with the specs of 220v, 11.3 amp, 2.6 kW/max 3.1 kW, 50 Hz) to power the pump, when I turn on the control box for the pump, the generator will buck and rattle like crazy, often conking out immediately (and I need to manually turn the generator on again, which stutters into finally working). It sounds like it is working hard, for sure. And it does work hard: this generator powers the pump so that it brings up about 40 liters per minute. Also, I need to set the control box at 8.5–9 amps, else the box auto-shuts off after a minute or so of running.

I can't figure it out. The Honda needs more amps set at the control box to stay running the pump, but also powers it such that the pump brings up the least amount of water...sometimes not even bringing up water (I restart the system, then it works again).

The Einhell needs less amps set at the control box to keep running, also, the initial power on surge nearly seized the generator until the power drain levels out. But wow, what a greater amount of water being pumped up.

The only difference I can see is that the pump and the Einhell run at 50 Hz, while the Honda runs at 60 Hz. I did some research and read that it should not make a difference.

So why is the stronger generator pumping less water, while the weaker generator more...and why must I set the amps just in order keep the control box from shutting the system?

Thanks in advance,
Steve

*was first posted in the incorrect Thread.
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Old 03-16-2016, 10:47 AM
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Sounds like a common ground issue. The Einhell seems to copy standard proto call. (2-120 v.a.c. legs in reference to the common, or ground) These two legs are 180 degrees out of phase. When tested between the two legs, you see 220 v.a.c. (NOT using the common as reference to either leg)

Perhaps the Honda is only putting out one single "Phase" at 220 v.a.c.? (One leg in reference to common) It is a welder and may not be wired for two legs @180 degrees out of phase to create 220 v.a.c.. That apparently is what the pump wants to see..

Just a guess..
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Old 03-16-2016, 12:46 PM
steveb steveb is offline
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Thanks for the reply.

So, because the Einhell is two legs, it is therefore causing the pump to work at 4x the speed at the Honda?
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Old 03-16-2016, 03:11 PM
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Not faster but stronger. The motor uses the separate phases to work with each other to create double the torque at half the current.

There are two field windings that uses both phases to induce a magnetic flux through the stator, hence a higher flux field, being the phases are 180 degrees out of phase. (Totally opposite of each other)

Think of two magnets with opposite poles pulling towards each other. Same effect. Twice the pull than a single magnet sticking to a piece of iron..

"IF" the Honda is producing a single phase voltage at 220 v.a.c., the voltage is being divided between the two windings in the field but producing only half the torque. Both windings are in phase with each other and only producing half the flux..



Figure 2 represents 120/240V single-phase with two voltages 180 degrees apart with neutral and ground halfway between the two voltages. The voltage measured between the two legs is 240V, and since neutral is halfway between, the voltage from either leg to neutral would be 120V.
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Old 03-16-2016, 07:35 PM
steveb steveb is offline
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Thanks 12vman. Some detailed info there to consider.

Still wondering something, however:

The Einhell needs the control box to be set at 8.5–9 amps, else the control box will auto shut off.

The Honda needs the control box to be set at 12 amps, else the control box will auto shut off.

The Honda is what, 13.6 amps, while the Einhell is 11.3 amps.

If the Einhell is stronger than the Honda, why is it that the Honda seems to "take" the power on surge so easily and runs smoothly, while the Einhell runs like a maniac and has a hard time taking the power on surge (though I think it is because at power on surge, the control box/pump is demanding 4k Watts, while the Einhell has a max W at 3.1 kW)?

Thank you.
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Old 03-16-2016, 10:35 PM
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I'm thinking the Honda is putting the power through both field windings of the pump motor in series instead of going through "Each" coil as a separate load with the ground or common as reference.. (1/2 of the ohmic load but much more inductive load)

Looking at the image I posted above, imagine the Honda applying power at the upper and lower connections of the coils and not using the connection in the center. (the common) This would cause less resistance to the generator (more ohms because it's using both coils in series) BUT the motor is trying to work very hard because of the lack of magnetic flux in "proper amplitude". The "induced load" created between the field and stator will try to keep up with itself. (require more current to try to keep in "time") The potential of the motor would be less than half..

The Enhill is applying the power correctly, it seems. 2 separate 120 v.a.c. sources (2 separate windings in the generator instead of one creating 220 v.a.c.) 180 degrees out of phase and using the center connection as common for both. Each field winding in the motor is getting power from a separate circuit in the generator..

If you do the math, the Honda is creating almost 3k watts. (13.6 amps X 220 volts) **I'm assuming a single coil generator making 220 volts** The ohmic load to the Honda would be half compared to what the Enhill would see. The extra power is being lost in inefficiencies and not being seen as an actual "load" to the generator, hence the ability to handle the load better/easier..

Doing the math on the Enhill, it's making 1356 watts per winding/phase. (11.3 amps X 120 volts) times 2.. 2712 watts. (I'm sure the current monitor circuit only watches 1/2 of the generator_1 phase) The ohmic load is twice of what the Honda sees and the efficiency of the motor is going to be much greater. The actual power demand is going to be greater because the motor can now do its thing properly, hence the grunting of the Enhill..

**Disclaimer**
I'm not an engineer but this is how I see it..
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Old 03-18-2016, 04:11 PM
steveb steveb is offline
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Thank you again for the reply.

I checked a downloaded PDF of the manual for the Honda EW171, but for a 120v version—there is a electrical diagram, but beyond that, there is nothing close to a description of whether or not it is a single coil generator.

Anyway, it is interesting to get a better idea of what is going on here.

I think that since my Honda isn't really strong enough to pump water at the rate I need, and the Einhell seems at the maximum of its power output...I better look into getting a stronger generator, in the near future.

Or better yet: a solar powered 24v pump!

Cheers.
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Old 03-18-2016, 04:39 PM
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Check your voltage to ground on each "leg" , should be 120 and
check your voltage across both "legs", should be 240. That should answer part of the question.
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Old 03-18-2016, 04:40 PM
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The Honda EW171 is a 120 v.a.c. unit only. What model do you have?
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