Help with 115v SlowPump Please

[shaniac]

My 115V Dankoff SlowPump Surface pump just stopped today. Power is still getting to it but all it does is hum. I removed the head to confirm the head is not jammed. I checked the brushes and fuse to make sure all were fine. All looked well.

I removed the cover on the cooling unit (at the back) and that spins freely, so I know the bearings are all fine. The motor spins by hand freely, just not when I give it juice. Even with my finger assisting it.

Any advice or any other testing I can do, before I determine it DOA? I would liek to make it work again so i can at least pump water till a replacement arrives.

Thanks in advance.

- Shane

[wpowokal]

Since it humms it's getting power so a shorted or open winding, time to get the buckets moving water.

Just my opinion, and I have been known to be wrong.

allan down under

[kurt]

does it have a start/run capacitor sometimes a 120v motor will just sit there and hum when the cap is bad.... should be able to buy a new one at a motor shop like johnstone supply  or somewhere like that for $20-30 if it has one. if the motor has a rather large capacitor on it or next to it first disconnect all power to the motor then short the cap with a couple screwdrivers to make sure it is not holding a charge then disconnect all the wires from the cap noting there positions for reassembly then take your multimeter on ohms setting and put one prob on each of the 2 connections on the cap your meter should start reading 0 then the numbers should rapidly start to climb. if it don't do that replace the cap.

[vawtman]

How much slop is in the bearings?It wont take much for the rotor to lock up.It will spin freely with no power applied.

 Just a thought.

[shaniac]

OK, I spend the day testing and this is what I have found.

If I plug the slowpump in to any 110AC receptacle at the house, the electric motor spins fine, so I know teh pump is ok. But if I plug the same pump in to the plug at the pump house, it just hums. The difference is that the pump house is several thousand feet or so away from the inverter, and the 10/2 gauge wire down there that has been working for years and years I think can no longer keep up with the pumps needs. (we are off grid, not that it matters.)

I got some advice from a friend tonight and he suggested that since the pump is several years old that over time the pump is asking for more juice than the 1000 feet of 10/2 can provide.

He suggested I test this by.

Checking the voltage at the house, then testing the same voltage under the motor load.

Next do teh same thing down at teh pump house and see how the numbers compare. He is thinking that i will find that the pump under load at the pump house is requesting too much power and he has some charts to compare what is needed. I am thinking I might need a new pump to replace the old one.

I plan to do these tests in the morning, any other suggestions while I am at it?

I also posted a few questions / answers above, in case they help.

As always, thanks so much for your help.

- Shane

[shaniac]

I do not think it has a start / run capacitor. Any one have any idea if an older Windy Dankoff Slowpump uses a capacitor? I am thinking it is too old school for that. But I do appreciate the suggestion.

[shaniac]

No slop in the bearings. The pump runs fine when I plug it in to a 110AC receptacle closer to my power house. So I think the pump is OK. I need to run some more tests to determine where my failure is. : (

[Flux]

Measure the volts applied to the pump when running near the inverter and then measure it at the end of the line.

It could be that your inverter volts are low for some reason and the line is killing it completely or perhaps there is a bad connection in the line that is dropping the correct inverter volts to something lower than the pump will tolerate.

If this is a msw inverter motors are not too happy anyway so a bit more volt drop may take it over the edge. If sine wave and you measure much under 100v at the pump you are on the low side. If msw then 15v less than you measure at the inverter should make you suspect line problems. The actual ac volts from a msw inverter depends on what you measure it with. True rms such as a Fluke would show about 110v most average reading meters may only show about 90v.

If the pump is free and bearings ok then I suspect something else has changed.

Flux

[DanG]

You say many 100's feet wire run - in conduit? Ground contact? Buried?

With unknown loss first thing is check or re-terminate all the wire splices (wire nuts are horrible outdoors, twist and solder if you can, then wire nut with tape protection) and check every receptacle wire for corrosion or other damage to the plastics or screw clamps or plug socket...

Something you also may want to check is if there is any current flowing through the loop when nothing is connected out at the well head.

We had our house and the next door neighbors underground wire runs to outbuildings gradually go bad - with symptoms starting as incandescent bulbs dimming over weeks until they only produced orangery light and then totally open circuit. Since both went bad within a year so nearby lightning caused insulation damage is suspected.

What was happening was shorts were developing that also lowered the carry capacity of that chunk of wire beyond that point. If the conductors are not melted outright over the years the ground moisture produces copper oxide which builds up and spreads a thin layer until current starts flowing in a short circuit that is less than the fuse or breaker rating, which makes heat which accelerates the process until a full arc burns open the circuit or leaves it very high resistance.

Good luck, post back your findings.

[shaniac]

OK, using Google earth I mapped the wire run at about 850 feet. Using Windy Dankoff's wire chart the 10/2 wire I have in the run should be fine. But we could have guessed that from the ten years this thing has been working.

The local supplier of these pumps had some more great ideas too, so along with the other tests mentioned above I am going to check the circuit breaker the pump is on for a loose wire or any corrosion on the bus behind the breaker. That would certainly cause the loss as well as some of the great suggestions you have made. Sadly the wire is direct burial (AKA no PVC) so there may be issues with the RUN. "I HOPE NOT!"

I am also going to take a test strip down with me to the pump site and measure the current with about a 200W load, which is what we are estimating the slow pump to run at.

I will post all my finding later today. thanks so much for ALL your help gents, you guys are great!

[shaniac]

Ugggggg! What a day. I think I have tried everything. I pulled the breaker. It looked fine. I tightened all the connections I could find. Checked every connection box I could locate and everything looked wonderful. But each time I try a load at the pump, my voltage goes from 110 to 2 or 4. (two when trying the pump under load and 4 when i tried a kitchen blender under load. So unless I am missing something, somewhere in the 800 or so feet of 10/2 run, there is a problem. : (

So before I surrender entirely and run a new 800 or so feet of 10/2 (EXPENSIVE!!!) I am going to try and dig up the wire in mid run and check it out. If the same problem occurs that I see at the pump, then i know I am downstream from the issue. But if the pump works, then i know I only have to run new romex from the mid run. Agreed?

Now my only problem is finding the buried cable. It was trenched before I bought the property and I have no map. I spent half the day digging where I thought the line was and have not found it yet. Oh well.

Notes:

Voltage at house 110.

Voltage at house under 400W load - still 110.

Voltage at pump. with no load 110.

Voltage at pump with load. 4.

... at a loss. But as always thanks for any thoughts, in advance.

- Shane

[Flux]

There are ways of locating cables by applying an audio tone between cable and a remote ground point and detecting with a coil and amplifier but I doubt that you will have the kit to do that. There are commercial cable locators that do similar and you may be able to borrow or hire something.

I suspect electrolytic corrosion somewhere where moisture has got in, it is effectively open circuit apart from a bit of high resistance corrosion.

Flux

[DanG]

There are also electronic wire fault locators that use radar-like pulses for timing the end of wire reflected signal return to calculate distance to the fault. A good electrician's business should be equipped with them & know how to use it. You might even check the tool rental places to see if you could rent one for a day...

[bobopool]

  hi all

    to find wire under ground it very cheap to make get 2 metal coathangers and make each one in a [ l  ] shape on one end make it about 8 inches and the other end 4 inches now have one grip in each hand hold them out strait and keep them about 4 to 5 inches away from each other and walk slow about where the wire is buried and as you cross the buried wire the coat hanger will x and that wher the wire is buried try it it works for me good luck  tu  ......

[thirteen]

Some of this may sound stupid but you never know. Sometimes where the wire is clamped  either going into or out of a power box the wire will break inside. Since you do not know where it was buried and I'm sure you have thought of this but has there been adding or removing of a fence or gate where the wire might be buried or been disturbed. A tree may have fallen tearing it's roots up and catching the wire. Even where someone may have gotton stuck with an automobile. Maybe someone drove a nail into the wall where the wire runs. I do not know how deep it was buried. Could you possibly call the former owner and get some information. I always put a map inside the breakerbox of where things are either plumbed or wire run or buried. That is just me. Just some ideas? Best of luck.  If you find the break and are able to correct it you might get some heatshrink tubing and to help get a water tight seal.

[Airstream]

I'm curious how shaniac resolved this problem... Just another post trailed off into oblivion...