PDA

View Full Version : 3 Phase start/stop switch.



gearhead
01-06-2009, 09:42 PM
Need to buy a 3 phase start/stop switch for a Powermatic drill press. Looking for some help on a place with reasonable prices. I didn't know these switches were so expensive.

Fasttrack
01-06-2009, 09:47 PM
I had similiar issues with the motor control for my Pacemakers. I'm no electrician, so you might want to wait for input from some of our more electrically savy members, but the Surplus Center has some good deals. I found a solid state motor control rated at 10 horse for something like 60 bucks. Much much cheaper than the mechanical relays, but had the same basic features.

Boucher
01-06-2009, 10:16 PM
The cost is going to be determined by what you really want to do. If you need thermal imballance & overload protection you will need the correct heaters etc. with an appropiate contactor. If you are just wanting to turn a three phase 3HP motor on and off with a small switch, then a magnetic contactor from Grainger or from a local air cond supply house will do that and be cheaper.

J Tiers
01-06-2009, 10:28 PM
If it is 1 HP or less, all you need is a 3 pole "manual contactor"... i.e. a switch.

rdfeil
01-07-2009, 12:38 AM
Gearhead,

Depending on what you want to do, check out www.automationdirect.com they have manual motor starters rated from very small to quite large and the price is right for that type of stuff. That is not to say cheep, just reasonable. The manual motor starters have thermal trip settings to proteect the motor from overload built in. If you go that way you will need to know the full load current for the motor and order the corect switch. You will also need a box to mount it into and any accessories for the install. Check them out and you can download the specifications on the switches.

Robin

Usual disclaimers... not associated with AD just a satisfied customer bla bla bla :D

Ian B
01-07-2009, 12:47 AM
Gearhead,

What prices did you find?

Would this do it: http://www.surpluscenter.com/item.asp?UID=2009010622400318&item=11-2962-B&catname=electric
for $35.

Ian

Ian B
01-07-2009, 12:47 AM
Gearhead,

What prices did you find?

Would this do it: http://www.surpluscenter.com/item.asp?UID=2009010622400318&item=11-2962-B&catname=electric
for $35.

Ian

RetiredFAE
01-07-2009, 12:52 AM
Check the latest Grizzly catalog or web, seems to me I just saw these switches in there at very reasonable prices.

winchman
01-07-2009, 03:37 AM
I've got this contactor that came off an AC unit. I was told it works OK. The coil is 24 volts. I've checked the coil, and I get continuity across all three contacts when it's energized. I can't read anything on the sticker, but the wires on it were #8 IIRC. I got it for the coil, but I don't need it now.

http://img.photobucket.com/albums/1003/winchman/contactor002.jpg
http://img.photobucket.com/albums/1003/winchman/contactor001.jpg

PM or email me if you think it'll work for you.

Roger

gearhead
01-07-2009, 07:10 AM
Thanks for the help on this. Just looking for a simple start/off switch. THe motors on the press is 1HP. The machine was wired up as 440 3 phase, but has been changed back to 220. The press was wired up with a huge off/on work station all in 440 mode. Not sure if I can or want to use the extra extra large control boxs on the drill press now. I Like the work stations listed by Ian B.

Should note the drill press is a 1970 Powermatic 20" duel head.

Ian B
01-07-2009, 07:53 AM
On smallish 3 phase motors, you can either go for an on-off switch (a rotary isolator switch would be fine, as it's only 1Hp and not starting with much load, unlike, say, an air compressor).

Or use a 3 pole contactor like the one Winchman offers. If you use a contactor, you'll then need 2 push buttons (a normally open for start, and a normally closed for stop), possibly a transformer to power the energising coil (for Winchman's, that would be a 220v - 24v) and a box to put it all in.

I've made several of these. Pretty straightforward, but by the time you've found & bought all the bits, you'll probably have reached the $35 that Burden are charging for a ready-made unit.

One benefit of going the contactor route is that you can wire additional emergency stop buttons in, as many as you like. Just put them in series with the one on the box. They need to have normally closed contacts. Again, Burden have nice big ones: http://www.surpluscenter.com/item.asp?UID=2009010705433565&item=11-2520&catname=electric

(in case anyone's wondering, no, I don't have shares in them...)

Ian

gearhead
01-08-2009, 08:08 AM
Some of the trouble I'm having is the motor is rated at 17 amps for the 220 configuration. Most of all the 220 VAC 3 PHASE START/STOP STATIONS
have very low amp rating and I'm told not safe to use. I'm not an electrician so I would like any help I can get.....Gear.

Note: the numbers on the motor state AMPS 3.4/ 17. The motor is 220/440 and was originally wired in the 440 mode. I have direct wire the motor to my VFD and the machine works great. So I know the it will run if I can just find the right switching...

J Tiers
01-08-2009, 09:54 AM
Some of the trouble I'm having is the motor is rated at 17 amps for the 220 configuration. Most of all the 220 VAC 3 PHASE START/STOP STATIONS
have very low amp rating and I'm told not safe to use. I'm not an electrician so I would like any help I can get.....Gear.

Note: the numbers on the motor state AMPS 3.4/ 17. The motor is 220/440 and was originally wired in the 440 mode. I have direct wire the motor to my VFD and the machine works great. So I know the it will run if I can just find the right switching...

NO............

The amps are 1.7, that is , one point seven.......... Your decimal point is rubbed off, that's all.

The 220 amps are half the 110 amps, so it makes sense that way. 3.4 / 1.7.

The 17 amps would be 3740 VA, which would be equal to almost 5 HP of electrical input.

gearhead
01-08-2009, 09:58 AM
Thanks for the information, perfect timing too. This is a great site for anykind of help......Gearhead

Ian B
01-08-2009, 12:31 PM
Ah - now I see where you got the 20 amps from...

J Tiers is spot on; maybe worth having a look at the Burden Surplus starter box again? It has more capacity than your motor needs, it'll do 3Hp at 220V, 1.5Hp at 110V.

Ian

gearhead
01-08-2009, 01:21 PM
yes sir, I'm ordering two tonight. Thanks to all again......Gearhead

DR
01-08-2009, 01:29 PM
Thanks for the help on this. Just looking for a simple start/off switch. THe motors on the press is 1HP. The machine was wired up as 440 3 phase, but has been changed back to 220. The press was wired up with a huge off/on work station all in 440 mode. Not sure if I can or want to use the extra extra large control boxs on the drill press now. I Like the work stations listed by Ian B.

Should note the drill press is a 1970 Powermatic 20" duel head.

It might be easiest to use what you already have. A few coils will have to be changed.

If it happens to be an old obsolete starter changing those coils may be more expensive (or impossible) than replacing the whole unit though.

Boucher
01-08-2009, 04:24 PM
The 110 to 24 volt transformers that are used in A/C thermostat controls are also used in sprinkler controls, water softners and many other applications. They are about $5 at the Surplus Center or $10 at Home Depot. That is cheaper than changing the coil on a contactor. The Switch can be a standard light switch. You have to furnish the boxes.