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Old 02-19-2010, 07:36 PM   #1
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ancient NEMA 2 motor starter/control circuit quest's

bought this ol' ancient starter recently, not yet tested. it''ll eventually become part of my "10hp idler" rotary converter. I still need to test this thing/have a few basic questions.
please click the thumb for the big image

where I put the three green arrows, I guess, are the 'reset buttons' for the motor heaters. I'm not sure if the reset buttons on this thing 'pop outward' when the motor overheats, or do they go 'inward, toward the base of the starter' when they trip? ...has to do with how deep an enclosure I need to shop for...

would also like to know (assuming they 'pop upward/outward' when they trip) how far upward they DO travel? (enclosure depth required again :-)

on a somehwhat related matter: I have some allen bradley 800T pushbuttons I need to use for the control circuit of this starter. the coil in this starter requires 120VAC. so can my pushbuttons 'handle' straight 120VAC? or should I use them with a lesser voltage control circuit (and another contactor for 'switching' the 120VAC)? I already have a 120VAC/25VAC transformer, and two or three spare contactors I "could" use for the purpose, *if* it'd be beneficial.

also, for "way later" planning purposes:
do I understand correctly that having a 'lower voltage' control circuit (to the pushbuttons) offers me the opportunity 'down the road some' to more readily have a second 'wired remote' pushbutton station for the rotary converter a few dozen feet away or so? like able to use lesser gauge wire to/from the 2nd control station, I mean?

thanks for your advice on all this, too, you guys


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Old 02-19-2010, 08:39 PM   #2
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ancient NEMA 2 motor starter/control circuit quest's

That's an older starter, I can't remember if the buttons pop out or not. The way to tell would be to remove one of the heaters. These are the square things that have W63 stamped on them. In an Allen Bradley starter, removing a heater will trip the overload relay. The buttons very likely don't move at all, but will need to be pushed in after the heater is re-installed.

I don't have a heater table for the 709 starters handy, but for any of the other starters a W63 is for around 28 amps. These heaters need to be pretty close to the full-load current of the motor.

The 800T pushbuttons are actually a two part unit. The operator (the knob or button), and the contact blocks (the part on the back where the wires connect).

There are about 20 different contact blocks available, but the basic standard ones are rated for 10 amps and 600 volts AC. They are designed to operate a starter coil directly using any AC voltage from 24 to 600.

If you're going to use pushbuttons ( start/stop) to control this starter, you'll need one with a normally closed contact (like the red ones in the pic), and one with a normally open contact (usually with a black or green button). The N.C. is stop, the N.O. is start. You can connect any number of starts and stops, and using #14 wire, the total wire length can be very long. Like more than 500'.

You'll need to connect the overload relays into the control circuit, and you'll be using the 2 and 3 screws.

I'm going on vacation tomorrow (2/20) and will be back Thursday (2/25), if you need more help, there are about a half-dozen other guys around here who can easily walk you through the control circuit. (When I don't answer back, I haven't given up on you, I'm just not around a computer).



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Old 02-19-2010, 09:37 PM   #3
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ancient NEMA 2 motor starter/control circuit quest's

Your 800T-B's are rated 600 volts 10 amps. I suppose you could wire up a low voltage control circuit to close a 120 volt contactor using a 24 volt coil if you want to.

The allen bradley reset buttons I'm familiar with (not this one) pop out around 1/4" to 3/8" inch ... or they don't pop out or in you just reset the overload by pushing them in.

The control voltage makes no difference you can have as many 3 wire control pushbuttons as you want ... your wiring diagram will look like this whether it is 120 volts or 24 volts for the control circuit.
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Last edited by Stubbie; 02-19-2010 at 10:06 PM.
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Old 02-21-2010, 04:27 AM   #4
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ancient NEMA 2 motor starter/control circuit quest's

That is older style starter with indivual overloads and for overload button it will pop out about quarter inch outward direction.

As far for heater size that W63 is rated for 28 amp but I did have a chart somewhere I will have to find it in a day or two it kinda buried in the pile.

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