Well pump/frequency question

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  #1  
Old 01-27-11, 11:42 AM
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Well pump/frequency question

I have a 1HP Goulds well pump, looking to figure out if I need to adjust my generator, or get a larger one. I have the generator set for 62-63Hz at about 2 Kw load and roughly 123V.

I found out from the manufacturer that I need 6Kw to start the pump, mine is a 6250 surge. My question is.....how critical is the Hz when starting a pump like this? Seems I may need to be right at 60Hz...is 63 way to fast or within limits?

Generator is a Powermate 5000, I have a 20' gen cord rated at 30A for the larger wire to the inlet with a 20A male end. Entrance is a 30A inlet box then 8' of #8 thick-strand wire to a 50A double breaker....the length of romex to the pump is anyone's guess but the well is 20' from the house and 550' deep.

If I need a larger gen then that's what I need but want to make sure I have everything correct first. Would like to add...the well pump is the only circuit on the breaker and it's the only breaker I have on. I can get noise in the pipes but no start up...seems it's trying to start but no enchilada.
 
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Old 01-27-11, 12:01 PM
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Originally Posted by i6pwr View Post
I found out from the manufacturer that I need 6Kw to start the pump, mine is a 6250 surge. My question is.....how critical is the Hz when starting a pump like this?
Running 62 or 63Hz should be unrelated to the starting problem. Do you have a voltage meter that's fast enough to monitor how low the voltage drops as the motor is trying to start? Does the generator bog down or trip breakers when the pump is trying to start? Given the enormously deep pump, I think the voltage drop at the bottom of the well is probably too extreme to start the motor. You may need a generator that's capable of holding the terminal voltage very close to 120V.
 
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Old 01-27-11, 01:13 PM
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The gen doesn't trip any breakers.....you can hear it load up but keeps running.

I clamped one of the hot leads at the pressure switch, the volts on the Y axis are in amps....appears to have a rather hefty start-up, considering it's 2x the value.

Looks like it spikes at roughly 36A per leg......I think I may have found the prob unless I really don't need that much current.

 
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Old 01-27-11, 01:26 PM
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Oh one other very important question -- is this a 240V pump or 120V pump? Is the generator hookup 240V or 120V?

Also what exactly is the vertical axis on the graph measuring? The scale and label doesn't make sense to me.
 
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Old 01-27-11, 04:56 PM
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The vertical is 1mV per 1A, should have used a different scale, it's an early version and I cannot edit the values, each hash mark is 2A.

Pump is a 240V 2-wire single-phase, gen hookup is via 4-prong 240V, it's a Goulds 7GS10.

Here's the pump: 244 508 90 Super Stainless | 4-Inch | Franklin Electric



I was letting the water run through 3 cycles and the spike was very quick needless to say. The display read 20ish but the spike was so quick the 36 only displayed out of memory.
 
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Old 01-27-11, 06:19 PM
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Answer these questions and we can guide you.

Is the punp 110 of 220?

What is the model # of your pump?

What is the surge watts of your gen? It not known what is the model #?

The pump start up is based on surge watts and has nothing to do with HZ.

Amps X Volts = watts

I looked at your pump and there is no amp rating on site. From my calculation my 3/4 pump on 110 uses 2000 watts to start. You at 220 will use half that say 1000 watts. add in 1 hp and just say worst case you at 1500 watts. Your 5000 watt gen should be plenty and then some.

Mike NJ
 
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Old 01-27-11, 07:08 PM
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I have read many of your posts and you seem to be very competent with your plumbing and I admire that, but in this case, I think you are wrong on one thing. The watts on a pump wired for 240 volts will not be half that of a pump wired for 120 volts. Or....that's the way I read it to say.

From my calculation my 3/4 pump on 110 uses 2000 watts to start. You at 220 will use half that say 1000 watts
If I am interpreting your statement wrong, please correct me. Wattage would be based upon horsepower and not voltage.
 
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Old 01-27-11, 07:24 PM
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Your right I type faster then I think sometimes, its less amps same wattage.

Example: My pump 3/4 HP 110/220 Max amps 110 is 12.4. 12.4 X 110 = 1364watts...... max amps 220 is 6.2. 6.2 x 220 = 1364 watts.

Its been a while since I wired my house for gen use. Most of the time I learn something then forget when I am done with my project. I know I need to slow down when I post things and make sure I give correct info. Its a problem I have had all my life.....

I dont know everything but learn fast and am usally able to find the answer to almost anything online and master it...sometimes. Somethings are over my head....

Hey casualjoe how is the Drury Plaza Hotel at the Arch? I was there on a business trip in 08'.

Mike NJ
 
  #9  
Old 01-27-11, 07:33 PM
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Originally Posted by lawrosa View Post
Answer these questions and we can guide you.

Is the punp 110 of 220?

What is the model # of your pump?

What is the surge watts of your gen? It not known what is the model #?

The pump start up is based on surge watts and has nothing to do with HZ.

Amps X Volts = watts

I looked at your pump and there is no amp rating on site. From my calculation my 3/4 pump on 110 uses 2000 watts to start. You at 220 will use half that say 1000 watts. add in 1 hp and just say worst case you at 1500 watts. Your 5000 watt gen should be plenty and then some.

Mike NJ
Huh?

All those were answered in the earlier posts of the thread.

I understand about the surge watts...but was also asking if getting the frequency too far out of whack would play a factor aslso.
 
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Old 01-27-11, 07:48 PM
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I'm going say your issue is voltage drop more than anything else. What size wire is going to the pump?
 
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Old 01-27-11, 07:50 PM
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If they told you a 6000 watt gen to start your pump, your gen is 6250. That means at 6000 watts at 110 your pump draws 54 amps??? I find it hard to believe and I would need better info to calculate your issue.

I dont think frequency has much to do with it and is a clean voltage/dirty voltage thing, I think. This is where voltage regulators come in to smooth out the singnal. The sine wave on most gens are sloppy I think until you get into the high end stuff. Colemans are not clean as far as my coleman goes. Anyway I have no reg and the gen naturally puts out 130 volts standing. After load it ramps down to 120 or so. Most gens do this.

Mike NJ
 
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Old 01-27-11, 08:00 PM
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Mike, As mentioned earlier, the pump is 240 volt.

Pump is a 240V 2-wire single-phase, gen hookup is via 4-prong 240V, it's a Goulds 7GS10.

Here's the pump: 244 508 90 Super Stainless | 4-Inch | Franklin Electric
 
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Old 01-27-11, 08:11 PM
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Well in his first post he stated he is running the gen on 120V (123v) Maybe thats his issue....But then said 220 so who knows...

This is why I asked for info. The info seams all haywire..... Not enough difinitive info...

I will leave it the the electricians. But I like to cross over sometimes..

Mike NJ



Mike NJ
 
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Old 01-27-11, 09:06 PM
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I just typed this whole reply up.....and the page went blank

2nd try....

Being that i've been investigating this for awhile, it's becoming redundant in my head....so here's the skinny on my ramblings, trying to help in the blind I can understand your frustrations........

I measured the voltage on my trusty reactor, the Powermate 5000, from the 120V recepticles on the gen when I set the voltage. I was reading [email protected] 62-63Hz with a 2000W load. Across the L1 & L2 of the 240V 4-prong was roughly 245V.

The gen is hooked to the house via the 4-prong 240V.

Originally Posted by Tolyn Ironhand View Post
I'm going say your issue is voltage drop more than anything else. What size wire is going to the pump?
That's the reason I came back to add to this tonight.....was rolling around in my head that the house was built in 1978, the well was from what I remember about 200'. Back in 1997, the well was redrilled to 550' and the new pump was installed.






I haven't been inside the control box at the well yet, but here's the pressure switch....it appears to be #12 and I can only guess that it's the same wire running down to the ancient city of Beijing.

 
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Old 01-27-11, 09:36 PM
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Ok not an electrician but that is a 1 1/2 hp pump. And the SF in amps is on the plate at 9.8 amps max. 2254 watts will start that pump....

Motors are designed to deliver their rated horsepower under voltage variations of 10% of rated and frequency variations of 5% of rated. The combined variation of voltage and frequency is limited to 10%. When operated within these limits, with shaft load at or less than rated, the motor current and winding temperatures will remain within rated values, and normal motor life can be expected.

Ok. So I would think at 54 Hz or 66 Hz you will have an issue but not right away.

Mike NJ
 
  #16  
Old 01-28-11, 04:04 AM
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It is a 1HP, not a 1.5, the sticker depicts this and the model # is listed as a 1HP.

Is amps rated per phase? I'm seeing 10A running per leg.
 
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Old 01-28-11, 09:03 AM
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Your service factor is 1.4. It an uprated motor.

Pool Pump Motors from POOLplaza

Mike NJ
 
  #18  
Old 01-28-11, 11:00 AM
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Your service factor is 1.4. It an uprated motor.
No. Service factor means that the motor can be loaded to the percentage shown (140%) for a short period of time without immediate damage to the windings. This would not be uncommon with a submersible pump.

I strongly suspect that undervoltage at the pump motor is the problem. Single-phase motors will draw anywhere from three to six times their running current when starting and with your particular motor three times would be approximately 30 amperes. Even with #10 conductors you are going to be experiencing something on the order of 20% voltage drop (or worse) when trying to start that pump and I'll bet that even when running on utility power it has a hard time starting. Using the generator it is really dropping the voltage to an abnormally low level. The frequency drop is only a secondary concern.

Voltage drop calculator
 
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Old 01-28-11, 05:15 PM
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Hey casualjoe how is the Drury Plaza Hotel at the Arch? I was there on a business trip in 08'.
As far as I know, it's still there! I was near there yesterday, just a few blocks west of there actually on the other side of the convention center, but don't tarry when traveling through the hood.
 
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Old 01-29-11, 06:07 AM
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Originally Posted by Furd View Post
Single-phase motors will draw anywhere from three to six times their running current when starting and with your particular motor three times would be approximately 30 amperes]
So to understand this fully, if i'm clamping one leg and reading a 36A spike with roughly 10A running, my total draw is twice this correct?

When the utility is connected, the pump starts immediately, could be I believe it starts immediately but if I throw the switch, it clicks, them builds pressure within a second.

I've been eyeing a 50A gen that's 8KW continuous but has a 12KW surge which is generally higher than most surges on portable generators....usually it's 20-30% but this one has a 50% higher rating for surge.

I know I won't know until I try but I would think based on the graph, that a 50A surge should start the pump.

Debating a 10Kw surge NorthStar Generator — 614cc, 10,000 Surge Watts, 8500 Rated Watts, Gasoline | 10,000 - 29,999 Watts | Northern Tool + Equipment

But heard mixed reviews of this one: Generac Portable Generator — 12,000 Surge Watts, 8000 Rated Watts, 410cc Generac OHVI Engine, Model# XP8000E | 7,000 - 9,999 Watts | Northern Tool + Equipment
 
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Old 01-29-11, 07:48 AM
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So to understand this fully, if i'm clamping one leg and reading a 36A spike with roughly 10A running, my total draw is twice this correct?

When the utility is connected, the pump starts immediately, could be I believe it starts immediately but if I throw the switch, it clicks, them builds pressure within a second.
No, you don't double the amps to get the total draw. I think you suspect you need a bigger generator and I would agree.
 
  #22  
Old 01-29-11, 09:40 AM
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I have 3 gen. and they are all factory set to put out 132 volts and the 240 will be 264 volts
Just about all electric devices are made to operate 10% over or under rated volts. At this
out put i run my home in a power outage. I am only using one 5000 watt gen. so a can't run every thing in the house. When i want to turn on my 240 volt 1HP pump i turn off all other breakers and then turn on pump. I have never checked out volts or amps, but it does run it. Later Paul
 
  #23  
Old 01-29-11, 02:19 PM
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Without knowing the total length of wire between the generator and the pump along with the wire size(s) I cannot do the arithmetic to fully explain the problem. You stated that the well was 550 feet deep but it is possible that the pump is only 200 feet (or some other number) deep.

Since the utility power seems to easily start the pump I can only guess that it is a problem of the size of the generator, most specifically the rotating mass of the generator rotor itself. When the pump attempts to start the sudden increased output requirement slows down the generator faster than the governor on the engine can respond. This slower rotation causes the voltage output to drop (along with the frequency) and all this combined with what appears to be a very long electrical run to the motor causes a severe voltage drop at the motor preventing it from starting. A larger generator (higher output rating) will have more mass in the rotor and will not slow down as much before the engine governor supplies more engine power and therefore may start the pump without problem. This is often a problem with using standby generators of modest size (compared to the utility load) for well pumps.
 
  #24  
Old 01-31-11, 07:02 AM
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I agree with furd's analysis. The HZ problem is secondary. The generator is not robust enough to start the pump.

Ways to solve the problem:

1. Get a bigger/ better generator. Im partial to honda, but thats just me.

2. If possibile, run larger wires to pump. Think 10 or 8.

3. all of the above


P.S. Trying to start the pump with an inadequate genny could damage the pump, the genny or both.
 
  #25  
Old 01-31-11, 10:50 AM
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Originally Posted by Auger01 View Post

P.S. Trying to start the pump with an inadequate genny could damage the pump, the genny or both.
I agree, i've accepted the fact I need a larger gen...no sense trying to damage something. A 25A menu won't satisfy a 36A appetite.
 
  #26  
Old 01-31-11, 11:19 AM
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Yep I think that is the issue here, especially given the very long circuit conductors. If you only had 50' of wire between the genny and the pump I think there's a good chance it would start, but with that much wire you essentially lose 10-20% of the power you put in by the time it gets to the bottom of the well. That means you really need a good sized genny to keep that voltage as high as possible at the top of the well so enough gets to the bottom to start the motor.
 
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