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texjames
06-21-2011, 08:29 PM
New guy first post. I have a old U.S. Machines Vertical Mill i been learning on.
having a blast with it.It has some really old tech power switch i'd like to upgrade to something better.See the pics below.Power comes off the phase converter to switch, then go's to motor, another cable running up through
belt cover hood on top go's to reverse switch.Any idea's on a better power switch? Thanks!
http://i113.photobucket.com/albums/n225/texjames/e3cbd12a.jpg
http://i113.photobucket.com/albums/n225/texjames/f7b070f7.jpg
Here below my oldie goldie...needs lots of TLC and those yellow wheels got to go soon...
http://i113.photobucket.com/albums/n225/texjames/c47d0f94.jpg

DFMiller
06-21-2011, 08:51 PM
Nice looking machine. Welcome aboard.
I got lost looking at the wiring. The disconnect (Orange box) is connected where? Between the incoming power and the phase convertor or the phase converter and the motor. I noticed that one of the fuses is missing and maybe jumpered out.
If I were doing it would have some kind of disconnect on he phase convertor and then a properly sized 3 phase power switch to the motor. What is the nameplate on the motor and the phase convertor say?

texjames
06-21-2011, 09:25 PM
Nice looking machine. Welcome aboard.
I got lost looking at the wiring. The disconnect (Orange box) is connected where? Between the incoming power and the phase convertor or the phase converter and the motor. I noticed that one of the fuses is missing and maybe jumpered out.
If I were doing it would have some kind of disconnect on he phase convertor and then a properly sized 3 phase power switch to the motor. What is the nameplate on the motor and the phase convertor say?

It has a Phase-a-matic converter Model PAM-200 rated for 3/4 to 1 1/2 HP motor.My motor plate info is long gone but others i've talked to seem to think these had about 1 HP motors.Here is a link to the Phase-a-matic and its doe's say not to run through fuses after the converter.It says in the instructions a magnetic starter is preferred.I'm really lost on the electrical part of this, Link to Phase a matic...
http://www.phase-a-matic.com/PDF/SIS.pdf

DFMiller
06-21-2011, 09:46 PM
A switch like this will fit the bill.
http://www.grizzly.com/products/Magnetic-Switch-3-Phase-220V-Only-2-HP/G4672
I always like to go bigger if size is in question.
I am still unclear. Did someone just jumper out the fuses to suit the requirements of the phase convertor?
A tidy up of the wiring when the switch is added.
The reason a magnetic starter is recommended is so once it's off due to source breakers tripping, power failure etc the machine will no start back up when the power is restored.
I am all for giving most things a go but if you are not really comfortable with electrics finding some one who is is a great idea.
I hope you get lots of enjoyment out of the machine. It looks like fun.
Dave

justanengineer
06-21-2011, 09:48 PM
Knife switches are still in common use today, theres nothing "old tech" about them. The entire purpose of that switch is simply to disconnect power to the machine completely so that the electrical system can be worked on. The purpose of the fuses inside are the same as a circuit breaker or fuse box, to prevent the machine from drawing too much power. All that being said, the power should come from the wall, into the knife switch/orange fuse box, then go to the converter, then to the motor.

DFMiller
06-21-2011, 09:55 PM
I did not see the knife switch as it was hidden in the orange paint. ;-) my excuse is looking at pictures on 10.1" screen. Nothing wrong with it as a disconnect. If I recall they are not rated for many cycles of interrupting of the power at full rated load but for as just.... Disconnecting for isolation. If there is no other off / on switch something like I suggested will fit the bill.
Dave

texjames
06-21-2011, 10:23 PM
I was looking at the magnetic switches and had a thought.What about a single phase magnetic switch before going into the converter.Then i could do away with the knife switch box and clean up the wiring. I've done some wiring but might get a pro to rig this up however.

winchman
06-21-2011, 10:46 PM
Maybe you need something like this and a transformer to provide the power for the contactor coil.

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

It's a 3-phase magnetic contactor salvaged from a large AC unit.

DFMiller
06-21-2011, 10:48 PM
I guess that could work. A 220 switch is a double pole and a 3 phase has 3. I guess you would save a bit. Whether you could mount it in a convienent position is another question. I would put it in an easy to get position for those "Oh Crap" moments.
Asking a pro never hurts. I don't know where you are but some places are very strict about codes and inspection. Even if it's never going to be inspected there is nothing wrong with doing it properly.

I am using roto phase on my small mill. It had reversing switch on the machine. I just used a disconnect.

Best of luck and post the results. We all like pictures.
Dave

justanengineer
06-21-2011, 11:15 PM
I would recommend you keep the knife switch/fuse box arrangement and rewire it so the fuses are operational. If youre anything like me, then you have a LARGE breaker in the wall for welders or other machinery so the added protection of having fuses sized for the machine's motor would be well worth it. Also, the knife switch is useful not only for working on the machine, but also as a safety backup - flip the switch at the end of the night and the risk of an electrical fire, kids playing with it, etc etc are eliminated. Many shops do a similar trick at night by cutting power to all machines via a master switch. Its a very good habit to get into.

texjames
06-21-2011, 11:24 PM
That PDF of the instructions warns against fuses in between the converter and motor because if one side blows power is still going throught the other side.
I think i will go with the three phase magnetic switch after some more thought.
Put in about where the knife switch box is and be easy to get to.
My Mill is on a dedicated 230 outlet about 3 feet from the breaker panel.I use a welder on it sometimes but unplug the Mill if useing that plug for the welder.

JCHannum
06-22-2011, 08:48 AM
A magnetic starter or drum switch would be the best choices if you retain the phase convertor. But, if you are going to spend that much money, for about the same amount, you can get a VFD which will provide many more features.

It will replace the phase convertor and disconnect with a proper control. Additionally, it will provide a better power supply, variable speeds, braking, reversing and a much cleaner installation.

Rosco-P
06-22-2011, 09:53 AM
A magnetic starter or drum switch would be the best choices if you retain the phase convertor. But, if you are going to spend that much money, for about the same amount, you can get a VFD which will provide many more features.

It will replace the phase convertor and disconnect with a proper control. Additionally, it will provide a better power supply, variable speeds, braking, reversing and a much cleaner installation.

A VFD will not and should not replace the disconnect or knife switch. There should always be a positive means of disconnecting the machine from the power and that means isn't the circuit breaker.
A used three phase "starter" or motor control with a pushbutton station in size 0 or 1 should be cheap. Just have to replace the heaters with the correct size for your motor.

JCHannum
06-22-2011, 09:58 AM
In this case, the existing disconnect which I am recommending replacing is after the phase convertor. I have no idea what is downstream of that, which is where a proper disconnect should be located.

The added cost of the VFD versus the cost of a starter plus heaters is more than offset by the convenience of the VFD and the benefits offered.

Rosco-P
06-22-2011, 10:56 AM
In this case, the existing disconnect which I am recommending replacing is after the phase convertor. I have no idea what is downstream of that, which is where a proper disconnect should be located.


The static converter was likely added in when the mill was removed from the commercial/industrial environment that had three phase power. Looks like the disconnect box was used as a handy place to patch the converter into the wiring with no thought given to retaining it original purpose.

Rotary phase converter, build it once (5hp unit) and you're done. Retain original controls and wiring (if correct). Almost plug-n-play.

VFD(s), buy another one every time you buy another three phase machine, rewire controls, set parameters, etc.

lakeside53
06-22-2011, 11:09 AM
I went though this last week... I have many 3 pole knife switches, but they were physically too big, or only 30 amps, so didn't suit my my latest purpose.

If all you need is a 2 pole disconnect, head to Home Depot - $14.97 for a 60amp Square D disconnect... Heck, you can get a "pull out" type for $6.47! how can they do that?!


Here's the online store - my local prices were the same.

http://www.homedepot.com/webapp/wcs/stores/servlet/Navigation?storeId=10051&N=+90001+541745&langId=-1&catalogId=10053&cm_sp=d27-_-Breaker_Panels_Conduits-_-Subcats-_-Hero_04



If you want to use an industrial knife switch - ebay is your friend. Search on Square D disconnect, 30amp disconenct or many others. I get them for $10-15 all the time.

macona
06-22-2011, 01:54 PM
A VFD will not and should not replace the disconnect or knife switch. There should always be a positive means of disconnecting the machine from the power and that means isn't the circuit breaker.
A used three phase "starter" or motor control with a pushbutton station in size 0 or 1 should be cheap. Just have to replace the heaters with the correct size for your motor.

Dont need the knife switch as long as the machine is plugged in and not hard wired to the wall. A plug satisfies code requirement for a service disconnect.

Keith_W
06-22-2011, 04:05 PM
A suggestion,
You could look at using a VSD which would allow you to Start/Stop the Motor as well as haveing Forward and Reverse. You can also use a Rotary Pot to increase or decrease the Motor Speed thus allowing a better speed control. The VSD would have inbuilt Thermal Protection for the Motor. From your Wall Socket that would allow you to completly issolate the circuit if needs be I would wire into a Circuit Breaker then into a Contactor wired as a Latch Circuit, this is where you have the Emergency Stop Button wired to. From the Contactor you wire into the VSD and from the VSD it wires into your Motor. On the VSD there would be Terminals that you can wire the Forward - Reverse - Stop and Start Pushbuttons as well as connections for your Speed Pot. These can be placed in a small enclosure which would also have the Emergency Stop Button and you can mount this enclosure in a handy easy to reach location on the Mill, the Circuit Breaker. Contactor and VSD can be mounted in another enclosure either on the wall or side of the Mill. If you are looking at getting a VSD look at a Vector type VSD or one that gives torque boost.
Regards,
Keith_W.

Abner
06-23-2011, 08:35 AM
I too would recommend keeping the knife switch. Having replaced several switches on my table saw I went to an (old) knife switch and have never been happier. Works 100% of the time, and I can lock it out too! Important if you have small children who sneak into your shop to look at the 'cool' stuff inside.
:eek: