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Motor control box - Printable Version

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Motor control box - Mayhem - 06-09-2012

When I got my mill, the wiring was interesting to say the least.  There was a single enclosure on the back of the mill, which housed three 3-phase rotary switches, two 3-phase fuse clusters (the same type used by Noah) and a 3-phase outlet, into which the spindle motor is plugged:

[attachment=1805]

Beneath this, a plastic box was precariously hanging by one loose bolt.  Opening the box revealed two 3-phase contactors:

[attachment=1806]

A quick note:  here in Australia, single phase is 240v and 3-phase is 415v (440 measured between phases).  The idea behind using contactors is one of safety.  First, the contactors operate by energizing a coil using a momentary action switch. Once the coil is energized, any disruption to the power will result in the contactor opening, thus killing the power to the motor.  Therefore, it the power goes out (for any reason) the mill will not jump back into life once the power is restored (unless the start switch is activated).  Second, the contactor has a thermal overload, which will kill the power to the motor to prevent damage.  
There was however, one major problem here.  The two contactors (the x-feed motor and the pump motor) were wired to their respective rotary switches.  As these are standard ON/OFF switches, they keep the coil energized, meaning that they offered no protection.

I decided to gut the enclosure and start again.  Also, I didn't want to be reaching behind the mill to turn things on, so I decided to make a separate control box.  The enclosure was pretty beat up and had several holes that needed blanking plates welded in and a new hinge pin turning up.  Not to mention a fair amount of panel beating.

The old fuses were tossed and DIN mounted circuit breakers were used.  The control circuitry has its own breaker, as does the spindle motor.  The x-feed and pump motors share a breaker and there is a single phase breaker for aux power (light and maybe a DRO in the future).  I added an additional contactor, so now each motor is properly protected:

[attachment=1807]

The control box is simple enough and has a start and stop button for each motor.  It also has an emergency stop and three neons, to indicate the presence of all three phases of power.  On the rear there are the two auxiliary 10A power outlets:

[attachment=1808]
[attachment=1809]

Both were bench tested and the main enclosure was then mounted back into its original position on  the rear of the column.  I welded up an arm for the control box and mounted it onto the mill:

[attachment=1810]
I assume the mounting point that I attached the arm to is for a DRO.  If I get one in the future, it can be mounted on top of the control box.


RE: Motor control box - doubleboost - 06-10-2012

Nicely done
I do like to see tidy (and safe) wiring
John


RE: Motor control box - stevec - 06-10-2012

Great job Mayhem! Were you able to source the components from "inventory" or did you have to shell out hard earned cash?
That kinda stuff gets pretty pricey.


RE: Motor control box - Highpower - 06-10-2012

(06-10-2012, 06:50 AM)doubleboost Wrote: Nicely done
I do like to see tidy (and safe) wiring
John

I Agree. [Image: smiley-score010.gif]


RE: Motor control box - DaveH - 06-10-2012

(06-10-2012, 06:50 AM)doubleboost Wrote: Nicely done
I do like to see tidy (and safe) wiring
John

Smiley-signs009

A job very well done MayhemSmiley-signs107 Thumbsup Worthy
Smiley-eatdrink004
DaveH


RE: Motor control box - krv3000 - 06-10-2012

hi its all a black art to me welldun


RE: Motor control box - EdK - 06-10-2012

Nice job on the rewire. It looks safe now. Smile

Ed


RE: Motor control box - Mayhem - 06-10-2012

Thanks guys,

Some parts were out of my electrical box and others were given to me by a friend who is an electrician. All the breakers came out of upgrades. A new metal enclosure was $180 which is why I took the time to weld and panel beat the old one.

All I had to buy was the buttons on the control box, the control box, the armored cable and the lock. All up I am out of pocket to the tune of about $120. Small price for the safety and ease of use. Besides, now I know my kids can't play with it, so no worries about them killing themselves. Lathe will get similar treatment before being moved to my home shop.


RE: Motor control box - Rickabilly - 06-11-2012

It seems like every machine I buy needs this sort of thing done, My Radial drill had so much "safety" wiring, that it was just plain dangerous, with a semi functional DC spindle brake and three separate emergency stop switches only one of which affected a proper "No volt release" contactor. I just take it for granted now that any machine I buy will need a hundred pounds worth of wiring components and if it checks out OK then that's a win for me.

It gives me the opportunity to add little extras like your two single phase outlets, I did that on my Big Colchester, except I've got some three phase outlets as well for my coolant and Hydraulic copy attachment.

And I've gotta say the three neons one for each phase is inspired, It's so easy to lose a phase especially on older workshop wiring and not notice, thinking that the vibration and noise is due to some other issue, If one of those Neons is out, you know right there and then what the problem is.

Best Regards
Rick


RE: Motor control box - stevec - 06-11-2012

(06-10-2012, 08:17 PM)Mayhem Wrote: Thanks guys,

Some parts were out of my electrical box and others were given to me by a friend who is an electrician. All the breakers came out of upgrades. A new metal enclosure was $180 which is why I took the time to weld and panel beat the old one.

All I had to buy was the buttons on the control box, the control box, the armored cable and the lock. All up I am out of pocket to the tune of about $120. Small price for the safety and ease of use. Besides, now I know my kids can't play with it, so no worries about them killing themselves. Lathe will get similar treatment before being moved to my home shop.
That makes me feel betterSweat I get almost as much enjoyment out of my friends being able to profit by not having to spend" as I do myself.
The three neons is brilliant! (notice I didn't say "are" because neons aren't that "brilliant")