Oil filled - Adjustable contactor

[Alan78]

Hi,

I have recently purchased an old workshop that used to run three-phase, and have come across an old contactor with some sort of adjustable dash-pot, this pot contains oil with a small scale signed "TRIP AMPS" .
The contactor was part of wiring for a motor control (this controlled a roller shutter)

Now my question:

I have recently re-wound the motor so that it will work correctly with single phase, and would like to retain the old switch gear that controls it.
What would be the best way to test and measure the current "trip" setting on the contactor, as it does not show a real reading, just a rough estimate.
Also, what would be the best way to safely test the contactor, as i have never worked on oil-filled ones before ?

Thanks

Alan

 

[RF Lighting]

You must remove the contactor from service and replace it with a modern contactor and overload arrangement.

There is no reliable way to test the old dash pots, and it's designed for a 3 phase, not a single phase motor.

Also excercise great care when working on or near the old contactor as the dash pot reservoir will (should) be filled with mineral oil which is classed as a Group 1 carcinogen to humans.

 

[JohnW2]

Also excercise great care when working on or near the old contactor as the dash pot reservoir will (should) be filled with mineral oil which is classed as a Group 1 carcinogen to humans.

Whilst I can't knock anyone for advising caution, I do not think that anyone should get too excited about that, unless they intend to embark on a career of handling mineral oil!

Cancers resulting from skin contact with carcinogens are very rarely seen with less than a number of years of very regular ('daily') exposure. Dramatic though it may sound, 'Group 1' merely means that carcinogenicity has definitely been shown (rather than being 'uncertain'), and has nothing to do with the 'potency' of the carcinogen. There also are 'mineral oils and mineral oils', carcinogenicity only having been definitely established (IARC 'Group 1') for the least refined ones. Most engine oils and many cosmetics and skincare products are, or contain, mineral oils or derivates therefrom. Indeed, a good few food products contain ('safe') food grade mineral oils.

Kind Regards, John

 

[bernardgreen]

You must remove the contactor from service and replace it with a modern contactor and overload arrangement.

Sound advice,

If you want to keep the "antique" appearance of the control panel you could put the new control gear out of sight and operate the originals in parallel with the new without them switching any current.

Is it a dash pot or a heat pot where the oil heats up on the load current and if it expands enough ( on a prolonged over load ) it operates a trip to release the contactor.

Some of the old days engineering was very ingenious in the way it worked.

 

[Alan78]

thank you for the replies, just what i thought really

Thank you anyway

 

[ban-all-sheds]

//www.diynot.com/forums/viewtopic.php?t=216517&start=0