Thread: Know where I can get a remote to start/stop a 3phase motor ?

Is there anything which has not been discussed here before? I second Watson's solution: https://www.woodworkforums.com/f11/auto-dust-extractors-vacuum-cleaners-78571.

Good luck.

WEG make one called a Soft-Starter.

http://www.zest.co.za/ssw04starter.htm

Mat be a bit exxy just for a remote switch.

AT,

What size motor are you looking at and what do you want it to do?

Most 3 phase motors installed in a machine like a dusty will have a control unit rather than a basic on off switch. The control unit will have a 3 phase contactor module and most likely an overcurrent detector, as well as the stop and start buttons visible on the front.

The 3 phase contactor is basically a high current relay with contact sets for each phase of the supply plus an auxilliary set. To provide a latching function, power from one supply phase runs the contactor coil via the auxilliary contact set and the (normally closed ) momentary acting Stop switch. To activate the coil, a (normally open) momentary acting Start switch is wired in parallel with the aux contact set.

When the Start switch is pressed, it allows current to flow through the contactor coil, closing all of the contact sets. The now closed auxilliary contact then maintains the current path when the Start switch is released and latches the contactor in the operate position. To stop the motor, pressing the Stop switch breaks the coil circuit and releases the contactor, removing power from all three phases simultaneously.

If an over current protection unit is also fitted, it monitors each phase current and should any exceed an adjustable limit, a relay is triggered,and its contacts, in series with the Stop switch, break the current flow through the contactor coil, removing power from the motor.

In order to incorporate some form of remote into this arrangement, you could use a two relays with 600VAC rated contacts to mimic the two switches on the operator panel. The remote relays itself could be controlled in a number of ways, depending on what your needs were.

For example, an RF control system similar to those on an remote garage door, a mains remote like the one Watson discussed in the link above, low voltage physical switching system at blastgates in a multi source dust system could all be used as required. If the system selected involved bringing cables out of the motor control box, it is essential that appropriate isolation and protection are used to eliminate the possibilty of contact with mains voltages.

Hope this is making sense for you. The upshot is that remote control can be added to a normal 3 phase motor controller without a lot of expense or trouble.

thanks for the input. I know what you means, It has all been done before,,,,its just that I don't have much luck when I search for the good stuff.

It does look a bit exxy Cliff.

Originally Posted by malb

AT,

What size motor are you looking at and what do you want it to do?

.

Its a 5hp 3 phase.

You can buy these remotes from the place I'm getting my dusty from, but I was told that I have to make sure my motor starter works off a 120V coil. american you see. powers different over there and it sounded tricky so I didn't bother getting it.
http://www.clearvuecyclones.com/Order_Page.htm (done the page a bit)

Thought I'd be able to purchase something more suited to our power here.

Thanks for the info though Malb. I understand relays in so far as it being a means of controling a high powered circuit with something less powered. But how to hook that up with a remote is beyond me. I fear it maybe a bit too much for a regular sparky to do easily enough too. (without charging the earth).

Originally Posted by apricotripper

...It does look a bit exxy Cliff. .....

How about a big long stick?

Originally Posted by Cliff Rogers

How about a big long stick?

yeh. big stick....

or was thinking of one of those pull string switches hanging from the wall. simple enough. be cheap.

Originally Posted by apricotripper

yeh. big stick....

or was thinking of one of those pull string switches hanging from the wall. simple enough. be cheap.

A pull string switch is not quite right but close. At least 20m of string should provide some isolation from the 415 V in the control box You could run it around the shop near the ceiling with short hanger cords dropping of at at the machines hooked up to the dusty. Run it like the pull cord signals on the trams and buses, one pull for start, two for stop, three for emergency ( cut all power, get out the fire extinguishers, and call 000)

Provided that you could get 415V rated pull switches, one could be configured to either remote start or remote stop via the contactor coil. Two could do both. But three direct switching the three phase supply would last one or two cycles before the contacts were blasted out.

Jake is this an Australian spec motor? i.e 415V 3 phase. And does it come with a starter?

Originally Posted by malb

A pull string switch is not quite right but close. At least 20m of string should provide some isolation from the 415 V in the control box You could run it around the shop near the ceiling with short hanger cords dropping of at at the machines hooked up to the dusty. Run it like the pull cord signals on the trams and buses, one pull for start, two for stop, three for emergency ( cut all power, get out the fire extinguishers, and call 000)

Provided that you could get 415V rated pull switches, one could be configured to either remote start or remote stop via the contactor coil. Two could do both. But three direct switching the three phase supply would last one or two cycles before the contacts were blasted out.

Thats an excellent idea. Thankyou...reminded me of what I saw in a magizine once...a few cords all going to the same switch on the ceiling...and the switch button was depressed with a paddle of sorts under it....hinged. ...and the strings when through a screw eye and down to the lever end of the paddle. if that makes sense.

I know with single phase you can switch off by simply having the switch on the active or neutral.

So I'm guessing your saying , you can't switch off 3 phase in the same way ? Do all hot lines have to be switched off simultaneously ?

Originally Posted by NCArcher

Jake is this an Australian spec motor? i.e 415V 3 phase. And does it come with a starter?

I was assured it'll work here on 50Hz 415V. Fingers crossed.

The motor starter wasn't combatible however. Will get one here.