putting a soft start on a pump motor. I am chicken.

dsergison · Mar 25, 2015

I need/want to put a soft start on this 3phase 400v 4.5a pump motor. (edm runs off 400v boost transformer) Currently it draws too much startup current when it switches on the high pressure flushing pump and it occasionally trips out the EDM control safety and it all reboots.
That sucks.

the problem wasnt a problem for a while... now it is again..and I am a bit scared to mess with it.

I think I want to install this 3kw in place of the contactor I have now.... is it just that simple?

http://www.mouser.com/ProductDetail...Bn26ok4X16BmeQFqGfWMib7T1vcTNXsaCnhoCVfbw_wcB

motor info
60hz
P2 2.2kw
I~ 4.65 @380v
Imax 5.15 @380v

would seem a 5amp 1hp amp soft start unit would do but the motor also says 2.2kw so here I am a a 3kw soft start

dsergison · Mar 25, 2015

Motor plate

alonzo83 · Mar 25, 2015

Call the number,

They will probably be more than happy to help you chose a starter properly sized for your motor.

Customer Support (EatonCare)

dsergison · Mar 25, 2015

it's not the sizing so much as the question: -Is this a solution to my inrush control voltage problem? And is it really just plug and play solution or are there other gotchas that could possibly harm anything?

I assume I just put it inline downstream of whichever of those breakers/contactors turns the motor on. 3 wires in, 3 wires out, done deal?

I can't see the line voltage drop without capturing it on a meter. it's not much. but the control is VERY sensitive. it only switches about twice per hour so not a lot of start/stops.

RayG · Mar 25, 2015

Short answer is yes, that's what soft starters are specifically designed for.

Although that said, I'm surprised a small motor like that is causing a problem with inrush current. When an induction motor starts up the initial current draw is the same as the locked rotor stall current and that's usually 6x the nameplate rating. Motor contactors are rated for different time constants, the current vs time curve for tripping is a thermal thing, you might have the wrong contactor installed.

One other thing I'd check, and that is put a clamp meter on the pump motor to see what current it's drawing, I notice that for 400V operation it needs to be wired in Y configuration, if the machine was supplied as a 208V machine and the motor wasn't changed from delta, when you installed the 400V boost transformer that might explain the current trips.. ( unlikely but check anyway )

There are better places than Mouser to source Schneider Soft Starters... like a fraction of that price.

Ray

atomarc · Mar 25, 2015

You mentioned pulling the pump contactor and installing the soft start in its place...I think! If the current contactor is dedicated to the flushing pump and has motor protection for it, then the soft start, if it replaces the contactor better has some kind of O/L protection. I have installed a few and they do not have this feature. The ones I installer were put between the existing mag and the motor so the mag retained the protection.

Dedicated, true soft starts have typically been replaced by frequency drives that allow soft start (ramp up) programming, plus they have the capability to protect the load. Your linked soft start is incredibly inexpensive so it may be the real deal. If it isn't, think 'frequency drive'.

Stuart

dsergison · Mar 25, 2015

I don't know what configuration I have or how to tell honestly. I have residential single phase and a phase perfect. I wired the seperate boost transformer (that the used Charmilles Robofil 290 EDM came with) to the output of my 240 phase perfect, I checked the leg to leg output and slightly adjusted the taps, maybe 5 or 10 v worth to get it as close to 400 as I could, which is what the EDM specified for incoming voltage and have run it for a year or two since.

adama · Mar 26, 2015

IMHO you need to start right at your incoming fuse board, isolate it so its safe to work on and go through all your cable connections makeing sure there tight. This fault has the classic symptoms of a fault developing in the wiring some were. Other thing to check is the capacitors on the phase perfect, any bulged - damaged ones?

I think you have a fault some were hence why this is happening. Not just a problem that needs new tech added.

dian · Mar 26, 2015

my 3 x 380v 5.5 kw lathe doesnt trip the 16a breakers.

RayG · Mar 26, 2015

dsergison said:
I don't know what configuration I have or how to tell honestly.

Although I doubt this is the problem, It's easy to check, with power removed, take the cover off the terminal block on the pump motor, and you should see six terminals, they will be labelled U1,V1,W1 and V2, W2,U2 there will be shorting links between the terminals. if the links are between U1-V2, V1-W2, W1-U2 then it's wired for delta and that's wrong for 400 V, if the links are across the three terminals on one side, that is V2-W2-U2 are all linked, then that's wired for Y ( or star ) and that's correct.

If that's not clear, take a picture and post it here.

Ray

andrewmawson · Mar 26, 2015

Is the pump starting against a load, or is it's o/p open? If starting with it's o/p blocked it's starting current could be very high.

dsergison · Mar 26, 2015

It is not tripping breakers or dimming the lights etc... It drops the 400v input to 390v or so and it is so fast I can only see it if I capture it with multimeter min/max function. However this is enough to tell the control to shut it all down. About %5 of times on a bad day.

dsergison · Mar 26, 2015

I bought the machine running on 400v. I'm running it on 400v. I kind of assume my phase perfect or my house supply is to blame but those are not something easily changed. Nor can I unload the pump.

dsergison · Mar 26, 2015

I can buy a bigger newer phase perfect but tats a few grand

gbent · Mar 26, 2015

Can you reconfigure your boost transformer to give you 405 or 410 volts so you won't get a low voltage trip when you loose 10 volts?

dsergison · Mar 26, 2015

Yeah, I pushed it right to the limit of what the incoming power spec said... I am hesitant to go past because it's an old and barely supported very very expensive machine to replace and it is very electrically complex. The manual is pretty adamant about not being outside the spec at all. The control stuff is pretty much unobtanium.

I believe pushing the boost transformer more sort of increases the electrical "leverage" on the upstream load and has diminishing return?

I guess I will just buy and install the soft start and see. It's cheap enough.

wippin' boy · Mar 26, 2015

can you remove the pump from the edm control circuit and just drive it by hand coming right out of the wall and its own cheapo vfd maybe.
better yet how about a single phase pool pump or the like

SAF · Mar 26, 2015

Dsergison,

My .02¢ If it works as supplied sometimes(for years) but not all the time, my guess is that you have a problem with the existing motor starter or the pump itself. Adding a softstart may help the problem temporarily, but it won't cure the real source of the problem, which will probably continue to get worse as time goes by.

A 5A motor is a pretty small load as things go and should be easy to start without too much fuss. If the contacts in the starter are worn and it occasionally single phases when trying to start, this could be your excessive current draw and hence more voltage drop/ unbalance during startup. Likewise if the pump bearings are going bad or the pump is restricted or clogged this will also cause excessive current.

I would suggest you get an amp meter and check the current on each leg during startup and running conditions to try and find the real source of the problem, instead of adding more complexity to it. A softstarter downstream of a bad motor starter won't do you much good, or trying to drive a seizing pump bearing. Also open the starter contactor and inspect the contacts for wear or burning.

SAF Ω

Jraef · Mar 26, 2015

That type of cheap chit soft starter is not going to work in your situation. It soft starts the motor my choking off only 2 of the 3 phases. That reduces the torque of the motor and makes THOSE TWO phases pull less current, but the 3rd phase is still across the line and it creates a sever imbalance. That's OK if its a pump that will start in a few seconds, not very often, AND you have a true stable 3 phase supply. But you don't, you have a fake 3rd phase to start with from that Phase Perfect and all of the power is STILL going to come from your same single phase source anyway. So you will have spent your money and you will get no benefit from it, plus run the risk of damaging the Phase Perfect, the soft start, the motor, or any combination of all 3. Not worth it.

Before you waste that money, do this. In most IEC systems that use 400V, it is 400Y240V, then they use 240V for the control power by tapping off of one phase and the neutral. If you just boosted the Phase Perfect 3 phase 240V to 400V, and did not ground the Y secondary, your neutral connection inside of the machine is floating and subject to wide fluctuations. I would look at the wiring diagram and find out what's going on inside. Then make sure you have these two issues correct:
1) You have a Grounded Wye secondary on the 400V transformer
2) The phase that they are tapping off of to get the control power is NOT the one that comes from the Phase Perfect.

dsergison · Mar 26, 2015

Ground goes all the way to incoming panel. I'll check the contactor guts

putting a soft start on a pump motor. I am chicken.

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