Which Heaters for Allen Bradley Controls?

jbacc · Jan 8, 2021

Folks,

I recently purchased a Gemco 20" Standard Duty Shaper. The 3 HP 3 Phase Baldor motor was wired for 480 which I have since rewired and it works. I have to change the heaters in the Allen Bradley Switch and I am not sure which ones I need for the Baldor Motor. The current heaters are W42 and I have attached a photo of the front and back of the current heaters. The motor plate show it draws 9 amps when wired for 240.

Thank you in advance for any advice, guidance, comments etc as to what I need and possibly a source...

Joe

mjk · Jan 8, 2021

If your lucky inside the switch cover there should be a decal that lists all the different heaters.
If not look up/Gooogle the switch/starter numbers and you should find a chart

Found this

Allen Bradley Heater Tables | Charter Contact

jbacc · Jan 8, 2021

mjk said:
If your lucky inside the switch cover there should be a decal that lists all the different heaters.
If not look up/Gooogle the switch/starter numbers and you should find a chart

Found this

Allen Bradley Heater Tables | Charter Contact

Thank you, as luck would have it, the decal absorbed so much oil, you can't read it...

Thanks again for the link.

Joe

jbacc · Jan 8, 2021

Ok, I used the link to try to identify which heater I would need, please be patient with me but I think I need a W52 because my motor draws 9 peak amps. The heater looks identical to my current one with the exception of a post or protrusion on the back of the W52 and mine had a hole (sorry for the poor terminology). I attached photos of both in the hopes someone can educate me so I don't buy the wrong one.

Again, thank you to those who take the time to help.

Joe

mjk · Jan 8, 2021

Besides the amperage, you'll need to figure out whether you have size 0 or size 1
Probably the mounting ctr/ctr or the width of the heater
Goooogle is your friend
Quick search of Fleabay found W52's for $8/pc, not sure if they were 0 or 1 size

johnoder · Jan 8, 2021

This was replaced by a 509 and I selected W56 (14 amps) for a 5 HP 1740 RPM motor on 240 in a size 1 device.

List says it is for 509 and 709

Can you read the number on your "switch"?

Can you read what it is for at 240 three phase as to HP?

My 509 is a size 1

jbacc · Jan 8, 2021

Yes, that was confusing me too... I attached a picture of the inside of the box. Hopefully someone can guide me.

Thanks for your help.

Joe

Why do all my pictures upload sideways...Oy

jbacc · Jan 8, 2021

johnoder said:
This was replaced by a 509 and I selected W56 (14 amps) for a 5 HP 1740 RPM motor on 240 in a size 1 device.

List says it is for 509 and 709

Can you read the number on your "switch"?

Can you read what it is for at 240 three phase as to HP?

My 509 is a size 1

View attachment 310067

So once again, as usual, John Oder graciously shares his wisdom. I just went out to the garage and took a picture of the decal affixed to the backside of the cover. I could not really read it but it seems I can see the information better in the photo than actually looking at the decal with my two eyes.

I have attached the photo, it looks like it's a 709 control? If so, what heaters to I need for the three phase 3 HP motor that has now been rewired to run on 240 volts?

Thank you John and all those who have taken the time to help me, I truly appreciate it.

Joe

Allend Bradley Switch - Inside Cover.jpg

BTW, if W52 Heaters are what I need, I'm still confused about them having a protruding post and my current ones have a hole to accept the post that is attached to the switch. And, if I decide to go to a 5HP motor at some point, should I put higher amp heaters in?

johnoder · Jan 8, 2021

I can read its a size 1, so that is progress

Next step FLA for 3 HP on 230 (or 240). You could read this off your motor tag

Short of that, I look in the little yellow booklet Electrical Engineering Pocket Handbook

and it says 9.6 amps

List above says your W52 is 9.9 in Size 1

There are no doubt members that will know (better than me) which way they would go - on the money or a little over - or the other way

I will say the 14 amp I selected is low for a 5 HP which says 15.5 amps FLA - but nothing has come of that seemingly insufficient heater selection value since put into service 8 years ago

jbacc · Jan 8, 2021

johnoder said:
I can read its a size 1, so that is progress

Next step FLA for 3 HP on 230 (or 240). You could read this off your motor tag

Short of that, I look in the little yellow booklet Electrical Engineering Pocket Handbook

and it says 9.6 amps

List above says your W52 is 9.9 in Size 1

There are no doubt members that will know (better than me) which way they would go - on the money or a little over - or the other way

I will say the 14 amp I selected is low for a 5 HP which says 15.5 amps FLA - but nothing has come of that seemingly insufficient heater selection value since put into service 8 years ago

John, you're the best, truly.... Attached is the motor tag.

johnoder · Jan 10, 2021

I will say the 14 amp I selected is low for a 5 HP which says 15.5 amps FLA - but nothing has come of that seemingly insufficient heater selection value since put into service 8 years ago

Maybe if I ever take a big enough chip on the 12" P&W vertical shaper it will open up on me

GregSY · Jan 10, 2021

Help me understand just what these heaters are for...are they being used to keep the motor dry inside? Or for their resistance value? or?

kb0thn · Jan 10, 2021

GregSY said:
Help me understand just what these heaters are for...are they being used to keep the motor dry inside? Or for their resistance value? or?

They are overload protection. They open up if the motor is overloaded too long.

Me? I rewired a bandsaw from 480 to 208 and I just replaced the 3 overloads with new solid state overloads. Just a potentiometer to adjust the trip values. It didn't cost substantially more than buying heaters would have.

J Henricksen · Jan 10, 2021

It looks like your heater has come apart. W style heaters have the shaft sticking out to insert into the pocket between the mounting screws. N style heaters have a hole for the shaft sticking out between the screws. Try pulling the shaft out of the socket the heater goes over.
Overload heaters have a shaft with a ratchet gear on the end of the shaft. It is held in position by a lower melting point metal, lead/zinc, something. The coil in the heater housing gets hot enough to melt the lead when a certain ampreage is reached and the spring pawl inside the overload housing is released. When the lead cools, you push the reset and it catches the pawl on the gear and it on again.

beckerkumm · Jan 10, 2021

That starter originally used N style heaters. The N style were a little problematic, mainly if tripped and reused so many starters were switched to the later W style by removing the post in the starter. I believe there are some threads over at owwm.org about doing that. N heats are very cheap to buy for this reason. I have a whole box of them as i run vintage starters on my old woodworking machines. W are more expensive but still only a few $ each. The 509 is a newer and better starter but square and deep so it doesn't look right on old curved surface machines if that matters. Finding old starters is fairly easy, finding the enclosure is hard. Dave

Bill D · Jan 10, 2021

The heaters are just that, heaters made of resistance wire. Just like the wires in a toaster. Different diameter and length wires have more or less resistance. All the electrical current goes through the heaters and out to the motor or the other loads. If that current gets too high the heater warms up and that warmth trips a bimetal spring to flip the contacts open and shut off power. They are mechanically interlocked so if one gets too hot it switches off all three contacts at once.
More modern devices use an adjustable reostat instead of switching out heaters. The separate heater design does allow one contactor to cover a huge current range. You might have top stock several resostat models to cover that same range. I have never heard of a heater element going bad.
Bill D

markz528 · Jan 10, 2021

I tried to post the complete pdf file but was unsuccessful. I included the most important pages. This bulletin does not cover 709 starters but describes how to select an overload.

I think you would be fine with W52.

Allen Bradley Heater Selection Chart1.jpg

Allen Bradley Heater Selection Chart2.jpg

Allen Bradley Heater Selection Chart3.jpg

Allen Bradley Heater Selection Chart4.jpg

Cole2534 · Jan 10, 2021

Timely thread. I'm rewiring a lathe from 480 to 240 and learning about heaters in the process.

If I don't change them, it seems my 20hp motor would only be able to develop 10hp of power due to the reduced current capacity. That may or may not be an issue for the work I intend, but there's no reason not to try it.

Is that a fair assessment?

Sent via CNC 88HS

markz528 · Jan 10, 2021

Cole2534 said:
Timely thread. I'm rewiring a lathe from 480 to 240 and learning about heaters in the process.

If I don't change them, it seems my 20hp motor would only be able to develop 10hp of power due to the reduced current capacity. That may or may not be an issue for the work I intend, but there's no reason not to try it.

Is that a fair assessment?

Sent via CNC 88HS

Not quite. The amps is not linear to torque because of magnetizing current. Magnetizing current is usually 25 to 40% but as high as 50% of full load amps. So at half amps you would have less than 10 hp available.

3 phase motor hp = volts x amps x 1.73 x efficiency x power factor/746. At 50% amps power factor is fairly low due to magnetizating current.

I used a 460 volt 3 phase Siemens 20 hp 1800 rpm motor as an example. Power factor at 50% load is 66%. So I don't have all the necessary info to come up with precise hp but if I used 66% it would be 8 hp. My guess this motor would make around 6 - 7 hp at 50% amps.

jbacc · Jan 10, 2021

J Henricksen said:
It looks like your heater has come apart. W style heaters have the shaft sticking out to insert into the pocket between the mounting screws. N style heaters have a hole for the shaft sticking out between the screws. Try pulling the shaft out of the socket the heater goes over.
Overload heaters have a shaft with a ratchet gear on the end of the shaft. It is held in position by a lower melting point metal, lead/zinc, something. The coil in the heater housing gets hot enough to melt the lead when a certain ampreage is reached and the spring pawl inside the overload housing is released. When the lead cools, you push the reset and it catches the pawl on the gear and it on again.

I tried to pull the shaft out on both sides, they will not come out. It's odd becuase the heater is marked as a W style and yet, it has no shaft. I ordered 2 W style heaters but I have a feeling they aren't going to work.

I appreciate your help.

Joe

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