Furnas motor starter won't drop out

[jdunmyer]

Surely the COIl is not 480v. ????

The pilot light would be in parallel with the coil.

Actually, the coil IS 480 volt. I think the saw was wired for 480 when we got it. We also have an older Delta 12" table saw that's 5 Hp, 3-phase. When we got it, it was wired for 240 volt, so I had to change it. The combination starter on the thing is an antique, it has no fuses, just a disconnect switch, and the coil is line voltage. I don't remember the details, but it must be dual voltage; it's running on 480 volts now. I think it had a jumper or something to change the voltage.

And, I realize that the pilot light would be in parallel with the coil, that's why I said I'd have to use a transformer. I have pilot lights and control transformers, but they're in the other barn and the ground is covered in 4" or so of very wet, heavy snow. Before I fool with that, I'll probably just change the whole thing to one of those Allen-Bradly combination starters that I have on the shelf.

One of the big problems, of course is that it's intermittent and "usually" works as it's supposed to. In fact, it worked fine for several years, until maybe a year or so ago. I don't use the saw a lot, it'll often go idle for weeks.

[Superbowl]

I also have a Powermatic bandsaw with a two speed gear box that also came with a three phase motor with a starter. I think it was 3/4 hp. I really don't see the need for a three phase motor in a small bandsaw as you really don't need a fine control of motor speed in a saw. I stripped all that out and put in a single phase motor and put wheels on the saw so I can move it any where in the shop and plug it into a 120v outlet. I have several three phase mills and lathes running on vfd's where speed control is beneficial but just don't see the need for the hassle of three phase for a saw.

[rdfeil]

Surely the COIl is not 480v. ????

The pilot light would be in parallel with the coil.

Oh YES it can be and often is in older installations or very simple motor control boxes. Now the secret... The pilot light assembly has a very small transformer built into the device. The actual light bulb can be anything from 120 volt down to 6 volt. You must check the information on the pilot light body for that information.

[rdfeil]

Actually, the coil IS 480 volt. I think the saw was wired for 480 when we got it. We also have an older Delta 12" table saw that's 5 Hp, 3-phase. When we got it, it was wired for 240 volt, so I had to change it. The combination starter on the thing is an antique, it has no fuses, just a disconnect switch, and the coil is line voltage. I don't remember the details, but it must be dual voltage; it's running on 480 volts now. I think it had a jumper or something to change the voltage.

This is a quick but cheesy hack fix to the pilot light problem. When you changed the coil from 240 to 480 you did change some jumpers. The jumpers reconnected the coil windings from parallel to series for the higher voltage. To use your 240 volt pilot light what you can do is just connect the pilot light to the coil from the middle connection (your current jumper) with one light wire and the other light wire to either end connection of the coil.
If you do this check the voltage across the pilot light with the machine running. Make sure it is above 200 volts minimum. If it is less than 200 volts this hack will not work and may cause damage. If it is above 200 volts is is good for intermittent hobby use.

This IS A HACK. If you have the proper pilot light use it!! If not ......

[SVS]

Actually, the coil IS 480 volt. .

10-4……I suspected a misunderstanding but sounds like you’re on top of things.

[jdunmyer]

I have fooled with motor controls and relay/step switch logic for a very long time, and am well aware of how most of this stuff operates. At least the older stuff. When at the scrapyard, I scarf up motor starters, transformers from 50 VA to several KVA, control operators, etc. Most of my pilot lights are 120 volt input, with an onboard transformer that feeds a 6 volt pilot light.

Superbowl,
My 20" Powermatic saw is way too big and heavy to move around. It has (IIRC) a 1 1/2 Hp motor. With the 2 speed transmission and the Reeves drive, I can vary the speed from about 40 fpm up to 4000 fpm. There is no need for a VFD in this application. When I first got my J1 head Bridgeport, I ran it on the 3-phase power, but when I found a VFD, changed it to the 240-volt single phase supply. I agree that VFDs are magical and like them a lot.

I'm very fortunate in being able to get 3-phase power into my barn. Although it means a $28.00/month bill for just the meter, it also means that I use all kinds of motors that are mostly out of reach of folks stuck with single phase only. My 1900 vintage 24" X 7" planer, for instance has a 10 Hp motor, the hydraulic unit for my sawmill carriage drive has a 15 Hp motor, there's 2 Budget chain hoists in the sawmill that are 3-phase, a Lincoln 450 amp motor/generator (20 Hp) welder, and more. Many people look at a machine and have to pass because it's 3-phase, I just bring it home and hook it up.

[Noitoen]

From Noitoen above: With newer contactors long cable remote start stop cable runs will have problems if you use higher voltage.

Hate to tell you this but that place has been wiring that way forever, long runs rock dust and 480 volt controls. Heck some of the stuff I put in that factory in the early 1970's is more than likely still there! Never any issues, this is single wires in a metal conduit, not control cabling. Long runs equal a voltage drop.

Never had a problem with old stuff. Newer contactor coils are very frugal in power draw and even use integrated microprocessor controlled switch mode power supplies so that the same coil will work on a very wide range of AC or DC voltage supply.

The problem I had wasn't with one of these but if you don't know them already, you can read a little about it here:

https://express.ecsnz.com/au/abb-af-contactor-the-advantage-of-electronic-coils

Unfortunately it's long gone the time a coil is just a piece of wire wound around a bobbin. The must put a CPU in everything.

[wmgeorge]

Never had a problem with old stuff. Newer contactor coils are very frugal in power draw and even use integrated microprocessor controlled switch mode power supplies so that the same coil will work on a very wide range of AC or DC voltage supply.

The problem I had wasn't with one of these but if you don't know them already, you can read a little about it here:

https://express.ecsnz.com/au/abb-af-contactor-the-advantage-of-electronic-coils

Unfortunately it's long gone the time a coil is just a piece of wire wound around a bobbin. The must put a CPU in everything.

when I worked there they had a lifetime supply of motor starters and coils. I doubt this would ever be an issue. Heck they had just finished changing from 25 cycle to 60.

[Noitoen]

I still remember how you could get replacement contacts to repair even the smaller contactors. One of my favourite brands were Sprecher + Schuh. They were very common in South Africa when we were there

[wmgeorge]

Both plants I worked at were partial to AB Allen Brady the newer one had GE solid state controllers.