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Forum topic by eflanders posted 08-01-2017 12:33 AM 1563 views 0 times favorited 7 replies Add to Favorites Watch
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eflanders

219 posts in 1691 days


08-01-2017 12:33 AM

Topic tags/keywords: switch starter planer

I recently acquired a used Powermatic model 15 planer. It needs a new starter which is the same as a magnetic switch except without the on/off buttons. So I have a magnetic switch on order as a replacement. But please help me to better understand why magnetic switches and starters are needed or beneficial? I realize that they do offer thermal overload protection, but isn’t this just duplicating the purpose of the circuit breaker?


7 replies so far

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Aj2

1179 posts in 1638 days


#1 posted 08-01-2017 01:03 AM

If the power to your shop was interrupted the planer will not start when it comes back.Safety first

-- Aj

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MrUnix

6022 posts in 2039 days


#2 posted 08-01-2017 02:35 AM

I realize that they do offer thermal overload protection, but isn’t this just duplicating the purpose of the circuit breaker?

No. The circuit breaker protects the wiring in the wall. The thermal overload protects the motor (and should be a manual reset, not automatic). And as Aj stated, the magnetic contactor provides a safety mechanism in the event of a power fail. It also allows the machine to be controlled via low voltage if needed (aka: Delta’s LVC).

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View Carloz's profile

Carloz

989 posts in 432 days


#3 posted 08-01-2017 05:14 AM

Magnetic switches came from industrial environment. Without them it would be difficult to restore power in a factory once it goes off. Since all machines are still connected to the circuit and the starting current of electric motors is many times higher than that of under nominal load when all machines try to start simultaneously the resulting load would trip the breaker every time. Magnetic switches help with that as all machines have to be started individually.
In a home environment magnectic switch is not necessary. In fact the equipment that is not intended for industrial use does not have magnetic switches, just a simple on/off toggle.

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MrUnix

6022 posts in 2039 days


#4 posted 08-01-2017 06:33 AM

<blockqoute>Magnetic switches came from industrial environment. Without them it would be difficult to restore power in a factory once it goes off.

That is just a happy side effect, not it’s primary purpose.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View Gilley23's profile

Gilley23

396 posts in 222 days


#5 posted 08-01-2017 09:52 AM

Not all starters/magnetic switches have overload protection.


Magnetic switches came from industrial environment. Without them it would be difficult to restore power in a factory once it goes off.

That is just a happy side effect, not it s primary purpose.

Cheers,
Brad

- MrUnix


View Sparks500's profile

Sparks500

95 posts in 171 days


#6 posted 08-01-2017 11:51 AM

Its also a way to have multiple start-stop stations on equipment. In many applications multiple E-stops are important.
All of my large tools, tables, bandsaw, drill press, and maybe jointer are have either gotten them or will be when I get that round tuit thing sorted out. ;)

-- Rockhound: You realize we're sitting on 45,000 pounds of fuel, one nuclear warhead and a thing that has 270,000 moving parts built by the lowest bidder? Makes you feel good doesn't it?

View Kelly's profile

Kelly

1821 posts in 2784 days


#7 posted 08-02-2017 04:44 PM

Magnetic switches are no less valuable to the hobbyist than to a professional. For example, I’ve been in the shop when grid power went down. It would have been easy to get distracted and forget the cabinet saw and dust collection were running [along with lights and radio].

Another example is, yesterday, my edge sander shut off unexpectedly. I played with the plug and switch, then hit the off button. Ten minutes or so later, I hit start and it was running again, only to shut off after a few minutes of run time. If it had a magnetic switch, it couldn’t restart, once the thermal reset disk bent back in place and closed the circuit.

Most larger toys, like my dust collectors, cabinet saw and jointer have magnetic switches.

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