Small Control Transformers, VF-2

[l u k e]

Just got my American Rotary phase converter in yesterday and am wrapping my head around the install. The instructions say that “all loads must be disconnected before starting the phase converter including small control transformers that may run the controls inside equipment." So the magic question is: will it necessary to run a disconnect switch with a VF2?

Thanks

[Matt@RFR]

Allways have the main breaker on the machine OFF whenever the phase converter is started or stopped. Apparently, phase converters can surge when started or stopped, and having the main breaker on the machine shut off will protect it from anything that happens in the line.

That's what I was told by a Haas tech, and it's been working just fine.

[haastec]

+1 for what Matt said.

[l u k e]

Thanks guys.

[gonc]

I've been chattin' with Luke thru PMs a bit and said I would call American Rotary about this since I had additional questions as well. I asked about the main power being turned off during a start up. Yes and no depending on the application. The bottom line being that there cannot be a load on the phase converter during start up. We all knew that already. For the Haas applications like I have, it is not necessary to turn off the main power since you have to manually start up the machine and there in not a load present if the machine is off. Other machines may be different they way they turn on. For example lets use a air compressor hooked up to a phase converter. If the phase converter is switched on and the air compressor is on, when you start the phase converter the compressor may call for more air and start. This would not be a good situation.
I asked about the surge with the American Rotary products during start up. Although the manufactured leg is higher than the others, it comes down once a load is placed on it. A surge, if any is not significant to do any harm what so ever.
The disconnects are used if you are running a 460V motor on the phase converter with a step up transformer. Here again, no load on the phase converter during power up.
I've been running my VF-0E on a 40HP American Rotary, no disconnects and I do not shut off the main power switch during start up and shut down. Its been working great with no issues.
Hope this all helps.

[l u k e]

I don’t know how relevant this is and it's NOT intended to be an argument; it just comes to mind in this situation, but I’ve been under the assumption most of my adult life that circuit breakers were not supposed to be used regularly as on/off switches. I don’t know how true it is but somewhere along the line someone told me that, probably 20 or 25 years ago.

[Ydna]

I wonder truly how much load is being pulled while the machine is off. Obviously a Haas will be very close to zero load, but any machine that has a battery backup somewhere is drawing a tiny amount of power from the wall when under the appearance of being "mostly off". We know the software has a battery, and the servo encoders might, though I don't think they do (I honestly never had to check).

I doubt it's enough to matter though, since anything being backed by batteries is being powered by DC anyway, so whatever supplies it probably went through a voltage regulator or some other system to prevent freaky surges.

I'm no expert, let alone in these machines specifically.....just some food for thought!

[HelicopterJohn]

I don’t know how relevant this is and it's NOT intended to be an argument; it just comes to mind in this situation, but I’ve been under the assumption most of my adult life that circuit breakers were not supposed to be used regularly as on/off switches. I don’t know how true it is but somewhere along the line someone told me that, probably 20 or 25 years ago.

Hi Luke,

I heard that same thing many years ago.

I built a home shop about 15 years ago separate from my house. I have a 150 amp service there which includes 120 and 240 volt single phase circuits. All the circuits are run in EMT conduit. As a safety (i.e. fire hazard prevention), I leave all the 220 volt circuit breakers turned off when I leave the shop on a daily basis. This may?????? also offer some protection against power surges. Then as I need them the individual circuit breakers are turned on i.e. (Hass TM-1P mill on 220 single phase, air compressor 220 single phase, Welder, 3hp homemade Rotary Phase Converter that I use for other 3 phase equipment). Note: The Rotary Phase Converter has a separate push button switch that actually turns the Rotary Phase Converter on/off that only works once the circuit breaker is turned on.

I have been doing this for the past 15 years and have not replaced a single circuit breaker yet. Just some food for thought.

John

[l u k e]

Yea I know, more than anything I wonder where that idea came from.