5 HP 3 phase motor

A mate has just dropped off a 5 HP 3 phase motor which has sat outside for several months, the gasket under the connection cover is damaged allowing water to enter the motor casing, the motor is seized solid. Before I waste my time stripping it down, what are your opinions on whether it's beyond help.

Thank You.

Ian

Scrap, trying to dry the windings will be problematical.

What a shame, I'm after exactly that size motor to beef up my rotary converter i doubt the water will have killed the motor itself, probably just rusted the shaft/bearings. worth stripping and cleaning up if you have a use for it. just make sure its thoroughly dried out before powering up.

Edited By John Stevenson on 27/10/2016 13:59:33

ian j

Strip it out and bake the case inc windings in the oven for a few hours, megger test for satisfactory insulation resistance between windings and case.

Emgee

We had to dry many motors from flooded pits in the factory, a spell in the oven in the rewind shop soon sorted them out. I once had a large Plc panel suite flooded from an overflowing gutter in a summer downpour. Switched it off and pulled all the modules and blew out the water from the backplane with compressed air blew all the water out of the relays and contactors left a large fan blowing in panel for a couple of hours and then switched it back on all ok apart from a couple of fuses in a pilz safety module, replaced and we were good to go. The watch room often "accidentally" spilled coffee in a keyboard so they would get some peace from the bleeper system. I washed it in a bucket of water, blew it dry and put it on the radiator for half an hour, it was lovely and clean inside and out and no longer smelled of coffee, they weren't all that pleased to get it back so quickly though!

Mike

Thanks all for the advice..

I will take it apart , give every thing a good derusting & stick it in front of a fan heater to dry it out. ( I doubt I could lift it high enough to put in the oven )

Ian

It will need more than a fan heater !

You need around 100* C for a few days at least.

Then a Megga test.

Take it apart as others have said, replace the bearings, clean things up as far as possible and dry it out. There are several ways of drying it out, don't think you will have a big enough over, so, fan heater, several bulbs using batten holder type lamp holders mounted on a short length of wood, or do as we used to pass a reduced voltage through the windings allow them to get quite hot to touch, unfortunately can't remember the voltage. It is surprising how quickly thing become safe to run. Check using the electricians favourite tool the 500 volt DC insulation tester the Megger. John

If you can borrow a dehumidifier it will dry it out better than hot air, you'll need to arrange some kind of shroud to blow the dry air through it. Of course if you heat it up as well it will be even better. Electric blanket?

A few weeks ago I pulled apart a 3 HP motor that was in a flood a couple of years back and had been left standing thereafter. The tide mark was half way up the rotor and it was still damp inside.

Hooking the stator up to an old battery charger (good for 4 or 5 amps) for a week sorted the insulation resistance. Cleaned out the rust and silt, fitted new bearings and terminal studs (these were steel) and it now runs silky smooth.

The only hiccup was failing to notice that the two bearings were not the same so had to exchange one - for which a public thank you to Simply Bearings for making this process easy and simple.

In conclusion I would suggest that your motor stands a good chance of being resurrectable. In my opinion you don't need ovens, de-humidifiers or any other fancy equipment unless you are in a hurry. Just be careful not to damage the insulation when pulling it apart.

Mike

Just to update you and thank you for all the advice.

I removed the rotor, took a rather large hammer to get it out,yes there was rust between the rotor and stator, I cleaned all this off.I tried the idea of connecting a battery charger to the windings but the charger got hotter than rhe windings, maybe I did not leave connected long enough. I found a piece of 6mm ally plate which was just the right width to replace the oven shelf and put the stator in for 6 hours at 50*. After it all cooled down I meggered it. .

After replacing the bearings I reassembled it and today connected it up and it runs perfectly.

So once again thanks for your help.

Ian