Starter puzzle

google

Member
Join Date
Aug 2002
Posts
11
Hi,

This is an interesting puzzle !!!! I recently came across a NEMA size 3 starter wired in a really weird way..... Has anybody seen anything like this before.....what's going on here

starter1.jpg
 
Its reversing the motor, probably a make shift replacement because the original reversing system went bad.

The reason for using the 4 pole contactor and one leg going thru a NC contact is to act as an interlock.
 
ARE YOU sure

The way this is drawn. When the starter on the left comes in the motor is going to single phase ??? The only starters i`ve seen wired simlair to this is a part winding starter which have two sets of overloads. How does this one work?

:site:
 
rsdoran: This starter is used for a pump so no question of reversing. Also this is working for 15 years now at customers site so I don't think this was something temporary. Also they have 3 more starters just wired like this.
 
The left-most switch (Aux Contact) on the right hand starter is probably a normally closed contact, (to prevent the single-phasing), which is opened when that starter is operated . When the left starter is pulled in the motor rotates one way. When the right hand starter is pulled in the motor rotates the other direction.

I'd never do it this way. Do you intend to correct this?
 
Last edited:
It appears to be 8536. He only needs one starter if this is for a pump or non-reversing application. If it's for a reversing application, he needs two starters and one O-load.
 
"The left-most switch (Aux Contact) on the right hand starter is probably a normally closed contact, (to prevent the single-phasing), which is opened when that starter is operated . When the left starter is pulled in the motor rotates one way. When the right hand starter is pulled in the motor rotates the other direction."

Sounds logical. Scary too because I believe there will always be a hot leg out at the motor.
 
The wiring is definitely reversing or braking, why it was done I dont know. Its not an uncommon method but its not one I like myself, as was mentioned when both contactors are off one phase is always at the motor. I am assuming the right most contactor is 4 pole with the first pole being normally closed.
 
Here it is

This is from the Square D manual part winding start.

squaredpart.jpg


Looks about the same I believe someone just rolled their on.
Like google never seen it done this way. Learn something every day. Thanks to Ron and to the rest HERE.

:site:
 
Thanks Tracy for that drawing from SquareD cat.

Both the starters are same (part # 8536). when I was at my customers plant I observed that the when the pump is called to run from PLC the right starter comes ON and then the left starter comes On after 1 sec.

I am thinking not to disturb the existing setup and just wire up my new PLC output at the same place as the old PLC output. As long as I don't understand the starter circuit completely I will not dare to cahnge it.
 
I reckon it could be part winding but usually you maintain phasing. Since this is a pump the possibility increases. The 8536 also doesnt seem to normally be a part winding starter.
Label the incoming phases A B C
Contactor on left is CR1 and contactor on right CR2
Phase B on CR1 is on center terminal
Phase B on CR2 is on right most terminal

That caused my original thought that it was reversing but the part winding makes more sense in this situation.
 
The Square D class number 8536 means an AC magnetic starter, their 8502 are contactors only. These are the basic building blocks of all other Square D starters. Look at the enclosure for the correct assembled class number like 8630.
 

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