Will a 3-phase magnetic switch work on 1-phase?

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Old 01-11-13, 08:24 PM
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Will a 3-phase magnetic switch work on 1-phase?

I want to put a magnetic switch on my 1952 Delta HD shaper. I'm finding more choices and better prices on 3-phase switches. Will one work correctly on a single phase?
 
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Old 01-11-13, 09:33 PM
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Do you mean a magnetic starter ?

If not.....what would be magnetic.....how would it operate ?

Tell us what you want to do.
 
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Old 01-11-13, 10:40 PM
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Yes. .
 
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Old 01-12-13, 05:42 AM
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You'll only be using two of the three Line in connections and two of the three Motor out connections, and you will most likely have to change the holding coil to 120 volts, but one should work. Do you have a specific one in mind??
 
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Old 01-12-13, 09:06 AM
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If the starter has overload protection built in: You typically use all three heaters for even single phase service. Check your wiring diagram. Basically, one Line will run thru 2 heaters, the other Line will run thru only one heater. Check ratings of both the heaters (if equipped) and the coil, per Larry above.
 
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Old 01-12-13, 10:25 AM
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You would be adding a magnetic starter to an already built device. You would not need the heaters to be active as the motor is self protected.

Usually you run a mag starter because of high switching loads or the starting switch is not near the device (remote starting) or you need starter plus motor protection.

I'm trying to figure out how it will be beneficial to you.
 
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Old 01-12-13, 10:37 AM
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The wiring diagram I saw was specific--3P starter for 3P use, a 1P starter for 1P use. There were no instructions for wiring it different. These have only 1 current trip adjustment on the overload relay so I don't know if using only 1 phase of a 3 phase switch will cause enough heat, or if wiring contacts in series or parallel would work because of the limited range of the adjustment.

I don't know the inner workings of one of these overloads (3P, 3 heaters?, 1 adjustment) to know how it works.
 
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Old 01-12-13, 10:41 AM
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Originally Posted by PJmax
You would not need the heaters to be active as the motor is self protected.
Not on this 1952 hunk of iron
I'm actually not as concerned about overload protection as I am the power fail/tool restart safety of a magnetic starter.
 
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Old 01-12-13, 10:49 AM
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Ok.....so your thoughts are...if there is a power failure, the tool will shut down and not restart automatically if the power comes back on.

Is this a common problem there ?

If you are not concerned about additional overload protection of the motor then a three phase starter will work fine.
As Chandler mentioned....you do need the same voltage holding coil.

If you have a particular starter in mind.....give us a link and we'll check it out.
 
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Old 01-12-13, 12:21 PM
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Is this a common problem there ?
No--but I have insurance even though my home has never burned down or been vandalized

A 6-inch panel raiser spinning at 9000 RPM is a scary thing and I just want a way to shut it off easily, and prevent re-starts. A toggle switch under the top isn't much good in a panic.

For my tablesaw on the left I added the long paddle to the starter box so I can kick it off from any position I'm likely to be in--and even with both hands feeding a large sheet of plywood through. I want to do the same thing to the shaper on the right.


I was looking to do this as cheap as possible because my ultimate goal is to replace the motor with a 3-Phase one and control it with a VFD so I have adjustable speed, slow start, speed & current limits, etc, etc. If I (ever) do that all I will then need is Start/Stop push buttons.
 
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Old 01-12-13, 12:41 PM
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In refering to common problem I meant power failures.

In the link below......15.00.....3 phase mag contractor. Perfect for what you are doing. Get a normally open switch for START and a normally closed switch for STOP.

New Furnas Definite Purpose Magnetic Contactor | eBay
 
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Old 01-12-13, 01:31 PM
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my ultimate goal is to replace the motor with a 3-Phase one
Do you have 3-phase commercial power available?
 
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Old 01-12-13, 03:06 PM
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My Delta (similar to yours) has such a switch already incorporated in it. What are you switching it with, presently?? As a matter of fact, the "ON" button is in a shroud and the "OFF" button is in free air making it really easy to hit with my knee (sometimes accidentally) and turn it off.
 
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Old 01-12-13, 05:01 PM
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Machine Electrics

I'll try to address all the comments in one post. It should be a help to future Googlers

Originally Posted by chandler

My Delta (similar to yours) has such a switch already incorporated in it. What are you switching it with, presently?? As a matter of fact, the "ON" button is in a shroud and the "OFF" button is in free air making it really easy to hit with my knee (sometimes accidentally) and turn it off.
Many new "industrial size" machines today come standard with mag starters for their safety and ability to sense an approaching motor overload better than a simple circuit breaker inside the motor. Keeps the mfrs. lawyers & accountants happy. Safety wasn't a priority in 1952 so mine has an ordinary 1/2" long toggle switch. Can you imagine an owner's manual today telling the owner to stick a piece of sandpaper in their running motor to deglaze the commutator? Mine does.

Originally Posted by Nashkat1
Do you have 3-phase commercial power available?
No. The VFD (Variable Frequency Drive) would convert my 1P input to 3P output PLUS all the other advantages (variable speed from a crawl to 150% of motor rating, current limiting, speed limiting, slow start, current feedback motor speed regulation, ability to run a 220V motor on 120V main...etc. VFD's are fast replacing motor-driven phase converters because they can do all this cheaper & more efficiently. It's quite a temptation to spend the $$ to go 3P motor + VFD to get this kind of control. With hobbiests yanking 3P motors out of 2nd industrial hand machines & selling them on eBay for cheap + the dropping price on VFDs--it's totally reachable for a hobby woodworker to do this.

Originally Posted by PJmax

In refering to common problem I meant power failures.

In the link below......15.00.....3 phase mag contractor. Perfect for what you are doing. Get a normally open switch for START and a normally closed switch for STOP.

(removed link to oversized 3-phase 12HP 120V relay)
You're just effing with me, right? A 220V 1P 1HP magnetic motor starter with buttons in a nice compact box is under $80 new. There are 3P ones on eBay for $40 and that's why I asked if this would work.


I did some more Googling and have found a correct Shop Fox starter for under $50 shipped. That's a good price & I'll know it'll work correctly.
 
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Old 01-27-13, 07:08 PM
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FWIW:

Just to close the books on this thread I ordered the Shop Fox 240V 1P 1HP magnetic motor starter and internally it's a 3P device. There are contacts marked L1, L2, L3 and T1, T2, T3. L2 &T2 are unused when wired per instructions for 1P power.

Perhaps only 1 heater actually needs to be on an overload to trip the contactor.
 
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Old 01-27-13, 07:30 PM
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Yes......one heater on the active hot wire should be able to trip the overload.
 
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Old 01-28-13, 05:37 AM
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L2 &T2 are unused
As per post #4. Yeah, you won't need but one heater for it to fall off and stay off until you reset it.
 
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Old 01-28-13, 10:01 AM
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Just out of curiosity is only 1 overloaded heater needed for a 3P unit to trip (other 2 heaters seeing normal current)? In other words some sort of unbalanced load affecting only 1 phase?
 
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