Kellogg 331 compressor needs help.....

[Art Butler]

Good Morning,
I'm working on a 1976 year Kellogg air compressor for a friend. I've already done the valves in the head (found one broken spring). Unit is missing pressure switch and magnetic starter. I test ran unit and works very smooth with no noise.
I need help on sizing the Magnetic Starter. The motor is 1 phase 240 volts. The Amp rating on the motor tag shows AMP 28.5 and SER F 1.15.
Thanks.

 

[454ragtop]

Hi Art, and welcome. I used this pressure switch when my original failed back in 2015. Works well, not using the unloader function, it controls the mag starter. http://www.ebay.com/itm/Furnas-69JG...737111?hash=item281d728857:g:MVsAAOSwyLlXoO7v

I think you need either a size 1-1/2 or a size 2 motor starter, with heaters/overloads to match your 28.5 amps. Good starter info here http://wiki.vintagemachinery.org/Magnetic Starters Explained.ashx
I might have a used starter I could sell, can check tomorrow if you're interested.
HTH, Jim

 

[Art Butler]

Jim, Sizing a magnetic starter can be confusing. I was told you take running amps and add 10% to get total, or running amps and add the service factor. This brings up to 32-33 amps. This puts me on the high side of a 5hp rated magnetic starter with a adjustable overload. The ones like Square D with overload strips, I'm not sure how you determine the strip size. Art

 

[454ragtop]

Art, if by strip size you mean which heaters/overloads are required, there are charts that tell you which ones you need. Usually the starters have a chart glued to the inside of the cover of the enclosure. I'm sure Square D has charts, probably online, maybe by starter #?
Jim

 

[redmondjp]

Yes, there are two issues here - the size of the starter itself, and the choice of the heater strip used in the starter, which gives you the proper motor overload protection.

For that amp rating, assuming that it is a single-phase motor, you're going to need a NEMA 2 starter (unless you have a 3-phase motor table - those numbers are different):

http://www.southlandelectric.com/motor_starter_sizing_chart_for_s.htm

For the heater strips, you look it up in the table provided by the manufacturer.

Now if you are talking about an IEC starter (like most of the imported ones sold online), they are much smaller, less expensive, and usually have an adjustable overload setting. They work, but are nowhere near as robust as a NEMA-rated starter. If you do get one of those, make sure it's mounted inside of another junction box in case it decides to go haywire.

 

[Art Butler]

Wanted to give a finishing up date on the old compressor. I ended up purchasing a ''made in Japan'' magnetic starter rated at 40amp. I also bought gauge and pressure switch from these guys because they were very helpful to me and answered my questions.

http://www.ebay.com/itm/200687662896?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Sent pictures to show how the old girl turned out. The owner has decided to sell her for $900.00. O yes, I did install a toggle night switch on the side of the starter and yes, she runs like a top. Thanks All...