Reduced voltage motor starting

[Bob D]

I originally posed this as part of another post, but it was getting confusing so I have opened a new thread.
I am thinking of adding soft start devices to two pump motors to try to get rid of a slight flicker of the lights when the pumps start, and to reduce the inrush current as it seems to me that expecting the inverter to go from 20% to 150% in the blink of an eye is likely not doing it any good.
I have separately contacted Magnum to see if my concerns about any effect on the inverter life are unfounded.
My system consists of a Magnum MS4024 connected to a 790AH industrial battery using 4/0 copper cables about 6 feet long.
The inverter supplies 120V to the distribution panel.
The system works fine - I can easily start things like miter saws, a compressor, and even a 12" planer.

My water system comprises two pumps, each 1/2 hp, each with a running current of about 5A, and a starting inrush of about 25A. When either or both start ( it is possible that they start simultaneously but unlikely) the lights ( OED's and CFL) flicker momentarily, although computers and other electronics don't drop out.
The inverter input current goes from a background of 15-20A to 160 or so for one pump, and 250 if both start. This is all within the specs of the inverter and, as mentioned above, there is nothing other than the light flicker to indicate the pumps are starting.
To get rid of the flicker, and to reduce the spike at the inverter, I am thinking of installing Scheider Altistart (ATS01N106FT) to allow me to increase the starting period to, say, 2 seconds, in an effort to get rid of the flicker by reducing the across-the-line starting spike on the inverter.

My original question was whether anyone had any experience with using a reduced voltage starter on a capacitor start motor.
I am also interested in any comments at all.

btw, I am pretty sure this isn't a wiring issue - I didn't scrimp on wire sizes.
Bob

[Westbranch]

Flicker can be the result of an under torqued connection in C120 V AC systems on grid.... took 3 of us 4 days to find it    in a seldom used ceiling fixture at the end of the line!    

[TomW]

Not sure if it applies:

Our submersible pump installer bored a smallish hole in the pipe just above the submersible pump so it did not start against the full column of water to the pressure tank. The hole let the water drain and never seemed to affect the pump pressure when it got going. That was some years ago and there may be an actual device to do the same thing these days.

Probably rules about releasing that water back to the aquifer now days, as well.

Miss the simpler days.

Just from the depths of what little memory has survived the ravages of time.

Tom

[Westbranch]

Hi Tom, ya it is a long shot but a possibility, that flicker was randomly intermittent. I thought it might have been the most used switch on that circuit, changed it and the problem went into hidinng for about 2 weeks...

And power droops in the house when the pump kicks in..... there since we moved in but the hydro co. says the incoming lines are balanced...

[Powerplay]

Water weighs about 62 lbs/cubic foot and depending on the column height your pumps are lifting, and how old the pumps are, that initial power surge might be required to lift the water past the siphoning point.  Cutting the tops off the start voltage spike might be harder on the pumps than anything.  Maybe a newer pump with more HP?  I looked back through for the pump's age and well depth but did not see it.  But you can probably figure that stuff out yourself anyway.

As to the answer you want, I have no experience with the Schneider device you're referring to.  It is an interesting concept.

[mike90045]

Not sure if it applies:

Our submersible pump installer bored a smallish hole in the pipe just above the submersible pump so it did not start against the full column of water to the pressure tank. .......

And my pump comes equipped with a pre-installed check valve so that the water IS retained to load the pump motor so it does not jump out of it's bearings.  And they warn not to defeat it.

[Bob D]

Thanks for the replies.

Unloading the pump can help, but an induction motor motor has an inrush current draw 5 or so times the full load current, even if the motor is unloaded, assuming full voltage across the line starting.

One of my pumps is a simple low lift jet pump, lifting water about 10 feet out of a well and pressurizing the house system. The second pump is a centrifugal used as a mixer in the water treatment (ozone) system.This pump starts against virtually no pressure, but still causes a very brief but noticeable voltage drop ( seen as a flicker of the lights) as the inverter increases its output.
Both pumps are new, high quality Goulds pumps.
I have talked to Magnum recently, and the drop I am seeing is expected, although it is likely only a few volts, during the 100 milleseconds or so that the inverter takes to react fully. They are not concerned about the inverter's life being compromised by what seems to me is pretty severe demands. So probably I will stop worrying about the inverter.
I'd still like to smooth out the pump starting, just to eliminate the brief flicker of the lights, and in the spring I'll install a couple of the soft start units and see if they accomplish what I hope.

[grgdgreek]

Abb also makes soft starters

George

[CDN-VT]

This was copied from Bob D original post ,so I moved it over :

If it is a deep well submersible I have removed the foot valve in the pump & installed in one way checks in the just before & after the pitless adapter .

That way the pump has no load on the starting , there still a surge , just not full load to overcome , since the pressure is held back and the pump spins up with less load ..
Just a trick I have used .  & I use two units to make them serviceable if need be .


VT

[WillEert]

I use a Grundfos 3/4 HP pump in my well. It is located 20' below normal water level and has a discharge head of about 75'. It comes with a built in discharge check valve and soft starter. My lights flicker with the Magnum inverters when my fridge starts but not when the well pump starts. I have looked around for a soft starter for the fridge but can't find one small enough. I found this company very friendly to talk to.

http://www.hypereng.com/index.html

If you find small soft starter that works for you please let me know.

Will

[CDN-VT]

I use a Grundfos 3/4 HP pump in my well. It is located 20' below normal water level and has a discharge head of about 75'. It comes with a built in discharge check valve and soft starter. My lights flicker with the Magnum inverters when my fridge starts but not when the well pump starts. I have looked around for a soft starter for the fridge but can't find one small enough. I found this company very friendly to talk to.

http://www.hypereng.com/index.html

If you find small soft starter that works for you please let me know.

Will

Any Pricing on these ?

[WillEert]

I bought the pump in 2010 and live in Canada so I am not sure how valid any price I might have would be. The pump model I have is a Grundfos 15SQ07 - 180. As with any pump it should be sized for expected conditions and flow rated required. This will affect the price also. I am very happy with this pump and Grundfos products in general. My radiant floor uses a Grundfos Magna which is also a very good product and very economical for power.

Will