Converting a Motor Starter

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Rick_B

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Good morning folks - I have a machine that came to me with a 1-1/2 HP 3 phase motor. I changed that out to a 1 HP single phase motor. The new motor is a 1725 RPM, 60 cycle, 115/220 dual voltage. I plan to wire it for 220 which has a nameplate FLA of 6.8 amps.

The machine came with an A-B 609T-AOW motor starter. From what I can find this is a 3 phase starter rated for a max of 3 HP. My plan is to use this with single phase input using terminals L1, L3, T1 and T3. I believe this is OK but would like to get that verified.

The bigger question are the heaters. The starter came with W68 heaters - from what I have found on the web this starter is NEMA 0 (and is marked as such) - the confusing part is that W68 heaters are not rated for NEMA 0 equipment (too big). From this chart http://www.discountfuse.com/W68_Allen_Bradley_Heater_Element_p/w68.htm (click on the selection chart tab)
it seems I need to change them out to W48 or W49 heaters.

Here's a picture of the starter in question

Starter2_zps3ad2a6d6.jpg

My questions:
1. what is the right size heater - are they sized based on FLA and is a little over OK?
2. Will any "W" heater fit the starter?
3. Is my overall plan electrically sound?

Thanks for any thoughts/suggestions you may have.

Rick
 
First things first, I am an electrical engineer, but in the UK, our systems are similar, but not the same, although I am familiar with AB control gear.
You seem to have got the basics ok, you will have to make sure that the contactor coil is connected between the two sets of terminals you intend to use so that the coil gets 220V between live and neutral, as opposed to between two phases. By "heaters" I assume you mean the overload heater coils. these are generally adjustable and you set the overload to the FLA (full load amps) of the motor, or slightly more, for instance for 6.8 amps you would set between 6.8 and 7 amps. If I understand you correctly, you seem to be on the right track, I should hang on a bit and see if you can get a USA confirmation!

Phil UK
 
Thanks Phil - I'll doble check that terminal strip to be sure it is connected. When I say heater I am referring to the overload but I'm not sure how you would adjust it or why they would have a whole series of W heaters based on FLA if it was adjustable?

You may have answered the question though - I need a heater very close to the motor FLA. I was thinking that maybe I would have to factor up for starting load?

Rick
 
Not all heaters are adjustable. Some are simply fixed coils of (probably) Nichrome wire. You do need the correct heaters for your motor, and using 2 poles of a three pole starter is fine. They are designed to trip out if any one of the current paths is overloaded.
 
Good morning Gents;

You size your heater from a chart that lists it for use in a single enclosure. Then pick one that matches the full load amps (FLA) on the motor nameplate. Start up currents do not last long enough to bother a over load if things are working correctly. Overloads are already sized to account for the 125% overload factor allowed by code. Normal overloads used in the USA are a class 30, meaning they are designed to carry 100% overload for 30 seconds before tripping. The enclosure factor is to compensate for the heat generated by other equipment in the same enclosure to try and avoid nuisance tripping. You have a single device in a single enclosure. You have a manual starter, the British fellow's remarks pertain to a magnetic starter, so you have no coil to connect.
 
Thanks Tony and Russ - sounds like my plan is workable. I will use W48 heaters in a NEMA 0 enclosure which should put me just under the FLA of the motor (6.65 versus motor FLA of 6.8)

Thanks
Rick
 
Not sure on the manual starter, but with an A-B starter with a coil, you want to connect your line in to L1-L2. The motor is connected to T1 and T3. Run a jumper from T2 to L3. The trip relays want current on all three legs for correct calibration.

John
 
I've been scouting ebay for W48 heaters - is there a reasonable way to test overload heaters to insure they are working?

Thanks
Rick
 
Rick_B said:
I've been scouting ebay for W48 heaters - is there a reasonable way to test overload heaters to insure they are working?

Thanks
Rick
Click to expand...

You should be able to pick up the eutectic alloy heaters at a local wholesale electric supply house.

Some instructions are here on Page 10 and 11 for these heaters on an automatic Nema starter

http://literature.rockwellautomation.com/idc/groups/literature/documents/pa/509-pa001_-en-p.pdf

Wiring for your manual starter A-B 609

http://literature.rockwellautomation.com/idc/groups/literature/documents/wd/gi-wd005_-en-p.pdf


John
 
I purchased a couple of W48 heaters from ebay (advertised as new) but I would like to be able to test the overloads. Giving this a little more thought - it seems the manual motor starter is just a sophisticated switch with overload and reset capabilities. The starter mechanism doesn't care about voltage or current. To test the overload and reset I need to apply a load exceeding the heater rating.

Assuming the above is true then I am thinking that I can leave the motor wired for 110. The source black would go the the L1 terminal, the load black to the T1 terminal and the neutrals (whites) would be tied together outside of the starter. This would allow 110 to pass through the switch and 1 heater. The motor should run for about 20 seconds drawing 13+amps then the overload should engage and shut it down. There should be no continuity between L1 and T1 at this point. Resetting the starter should restore the continuity between L1 and T1. Repeat above for L3 and T3.

Does this sound like a reasonable test?

Thanks
Rick
 
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