more motor starter heater questions.

j king · Aug 31, 2006

Hi all.I need to change the heaters on my cincinatti mill.I thought this would be easy but electrical never is for me.

I thought the heaters were on the sides of the starter but then got to thinking that there are only 2 so where is the third leg?Then a friend says to me that the heater is the little box in the middle with red writing on it.I disagree.Who is right? Is there only 2 heaters?here is a pic.Not the best .

BMyers · Aug 31, 2006

You are right. The little box with the red tag is the coil. Old A-B starters (and others) only had overloads on 2 of the 3 phases.

Carl Darnell · Aug 31, 2006

The two things with N29 are starter overloads. Some have two and some have three. It's hard to tell from the photo but I think the red box is the relay coil.

edit: Geez, I went to the shop to look in my book and posted without refreshing and got beat to the draw.

j king · Aug 31, 2006

Thanks guys.I just went thru this on my surface grinder but it was a newer type an d had 3 heaters.That is what had me confused.well,one of the things.
Since I have that straight can you tell me where I can find a chart that has the amp ratings or what the n29 or n19 stands for. Thanks alot.

Carl Darnell · Aug 31, 2006

You could go to the web site for the starter maker and do a search.

j king · Aug 31, 2006

I tried Carl.I have spent an hour looking at page after page.I need a lessen on google seaching.I dont think I ever find what I am looking for.I usually get sidetracked.

Carl Darnell · Aug 31, 2006

Tell you what. Tomorrow I will try to find something for you. What kind of starter and size, model# or part number is it?

j king · Aug 31, 2006

Without removing it to get all infro this is what I know. Its an A-B and size 0.It has N19 and N29 in it now and it was wired for 460.I changed it to 230 volts.Thanks for any help.If you need more I will remove it this weekend.
Jim

Carl Darnell · Aug 31, 2006

The heaters should be the same. How many amps are you going to draw or what is the Hp of the motor?

j king · Aug 31, 2006

I dont know off hand Carl.The one motor is 5 hp.The other 2 are smaller.The motor tag doubles the amps when running on the lower voltage.The heater keeps tripping on the hydrolic pump.I dont know why unless it is too low of a amp rating.
If you are thinking I have 2 different heaters numbers on the same starter I dont.I have 3 starters to change the heaters in. Jim

Carl Darnell · Sep 1, 2006

Oh, ok, Jim, I found this site that lists the heater elements but they suggest calling them to get the right ones. The chart on their site just lists the numbers available and does not tell what size starter or amp draw they work on. The site is www.southlandelectric.com and I found it by googling for allen-bradley motor starters. There are other sites listed in the google you may want to look at but give them a call and see what they have for you.

tools · Sep 1, 2006

EUREKA!

Found an old AB starter with the chart:

N19 3.85 full load amps
N29 10.1 full load amps.

EVERY old starter I've got only has 2 heaters, got no clue why, but it's normal.

Someone just put one in that fits. Match the correct N series element to the desired motor, voila, you're in business.

Available online at electrical surplus places for as little as $4 ea.

Rather than type the whole list, just post back as to the full load amps of your motor, at the operating voltage and I'll give you the N number.

Tools

PS Furthermore, may want to google Bulletin 609, size 0, 3 phase, ac manual starter (Allen Bradley) and see what pops. Catalog number 609-AAW, series E. That's the bulletin that details the N series heater elements. I noticed some on the AB website, learned all about 300 series controllers, but they're solid state...

Utilizing search engines requires EVERY BIT of my (albeit) rather dated computer science degree!

Geesh!

John Michael · Sep 1, 2006

In the old days motor starters only had heaters in 2 of the 3 legs. Sombody decided it wasn't safe and all 3 legs should have heaters. So - if you have a motor starter with only two heaters it is just flat old.
The AB heater tables have about 100 charts. A certain size heater may not be rated for the same current in a size 0 starter as in a size 1 or 2 starter. You have to check the exact chart for the starter or overload relay you have.
After AB got bought by whoever it is that owns them now their catalog got terribly complicated and non-user friendly.

j king · Sep 1, 2006

jeesh.nothings ever easy is it.

wippin' boy · Sep 2, 2006

replace the old starter
you'll be glad you did

Jraef · Sep 3, 2006

2 leg overload heaters were made illegal in the 1976 NEC! From that point on manufacturers were not allowed to sell them, but in reality they started phasing out old styles from inventory before that. That should give you a clue as to how old that starter is.

2 leg OL protection was "valid" in that on a 3 phase motor, you can never have power pulled from 1 leg without it going through the other 2. So you only absolutely needed to look at 2 out of 3 and that extra $1.13 it cost for the 3rd OL heater was a significant portion of some corporation's profit structure. The danger was that in the even of a grounded high resistance short on the un-monitored leg, the OL relay would not sense it and drop out the starter. After a few fires and losses, the NFPA decided the corporate profits of the starter manufacturers were less important.

tools · Sep 3, 2006

Referencing the above two posts, considering a well monitored motor in a home or small shop, the price of new starters...

How about just adding a third heater?

How about a carefully fused disconnect?

Any other options?

Tools

Carl Darnell · Sep 3, 2006

You can't add a third heater to a two heater starter relay. You could fuse the unprotected leg marginally low so it would blow easy. But that would create other problems. The best thing to do is replace the starter relay if you are uncomfortable with the two leg heater.

John Michael · Sep 3, 2006

You could also buy a freestanding 3 pole overload relay with 3 heaters. They are used regularly when one motor starter is used to start 2 motors thus requiring one starter and 2 sets of heaters. A freestanding overload relay is probably cheaper than a new starter.
They also sell a cheap line of motor starters called dedicated purpose starters. The overload relay on them usually contains no heaters and have a calibrated dial to set the motor current. Usually the starter and overload relay come separate. The overload relays cover a small range, you have to select the one that applies for your motor current. Dedicated purpose starters usually aren't repairable with new coild or contacts, they are throwaways if bad. They are also smaller than regular starters.

wippin' boy · Sep 4, 2006

----"They also sell a cheap line of motor starters called dedicated purpose starters."----

as a rule these don't have the latching contacts of a "regular motor starter"
with the missmatched mess you got now your protecttion is shakey at best
this old stuff IS going to "let the smoke out"
and if your unlucky it's going to take motor with it.
just move on

.
5 to 8 amp adjustable #7603K61 $126.82
mcmaster carr

and there's cheaper out there if you look around
try e-bay

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