3 Phase for CNC

[macgyver37]

There are many machine shops I know that are running the phase perfect systems in a similar situation as you are. Some of them are pulling Alot more than 200 amps too. If you want some first hand accounts go over to Practical Machinist and search phase perfect, you should get a few days worth of reading.

 

[River Runner]

Interesting....I'm obviously no electrical engineer or claim to know 10% of what an actual electrician knows but I found this article from an independent page interesting.

A true digital phase converter produces sine wave voltage, making it safe to power the electronics in the machine. It will maintain perfectly balanced voltage from no load to full load and can supply very large momentary currents, allowing the CNC machine to operate at maximum capacity. The converter does not have to be oversized to operate CNC machines, and as a rule of thumb, can be sized by matching the spindle HP of the CNC machine to the HP rating of the converter.

A digital converter has no moving parts, so there are no starting currents to cause line disturbances. With electronic power factor correction, it operates at unity power factor and does not consume reactive power. In fact, it will supply the reactive power needed by any loads it operates, making it a very utility friendly converter. The converter operates at 95-98% efficiency and when energized with no load consumes very little power.

A digital phase converter can operate multiple CNC machines or any combination of loads within its capacity. It supplies clean, balanced three-phase power that is of higher quality than utility supplied three-phase. The only true digital phase converter is manufactured by Phase Technologies. Some companies are marketing phase converting VFDs as digital phase converters, but these cannot safely operate anything other than single inductive motor loads.​

 

[River Runner]

There are many machine shops I know that are running the phase perfect systems in a similar situation as you are. Some of them are pulling Alot more than 200 amps too. If you want some first hand accounts go over to Practical Machinist and search phase perfect, you should get a few days worth of reading.

Wow, yes there seem to be many that are using this converter for similar CNCs

 

[River Runner]

To add more fuel to the conversation. This machine apparently has a built in soft start. Sales rep said they just installed one with a 27 hp motor powered by a RPC and there are no inrush problems because of the built in VFD and soft start feature.....

I think my bases are covered and I'm going to get it.

 

[Steve from Socal]

The short answer to the reason why Phase perfect can do what they say is the inverter stage is way over built Vs a single point of use VFD. The reading on Practical Machinist is very informative and features several real world examples of installations similar to your needs.

My shop has 480 three phase service IF I were to move to a location where there was only single phase a Phase Perfect would be the solution. They really are the best way to generate three phase, not the cheapest, at least in the short term. If you look at total cost in the long term thou, I think in power efficiency and quality they win the day.

A rotary phase converter has an idle load value, when you run a rotary the power to spin the converter is wasted. That can add up pretty quickly. For a hobby shop it is not a big deal, in a production shop the constant use of a large rotary is several KW day in day out.

 

[wyliesdiesels]

I know that a manufacturers claim may not always be 100% perfectly accurate but here is some verbiage.

Versatility


The Phase Perfect® can safely power virtually any three-phase application within its rated capacity. It can power resistive and capacitive loads as well as motor or inductive loads. Its power quality makes it ideal for powering demanding loads such as CNC machine equipment, submersible pumps and other voltage sensitive applications. The Phase Perfect PT Series can operate with 60 Hz input

the thing is, the phase perfect or any other VFD wont be able to do a soft start/slow ramp up for just the motor if the entire machine including the controls, only has 1 power input, since the PP or VFD will need to power the controls when the motor/saw is off.

So with the power being on already, the motor will have in-rush current....

 

[wyliesdiesels]

Power Company says no demand fees. But they recommend anything over 10Hp single phase be viewed by their engineer. This systems claims the grid will only see a 7.5hp start.

unless you can power the controls separately, I dont see how thats possible....

 

[wyliesdiesels]

To add more fuel to the conversation. This machine apparently has a built in soft start. Sales rep said they just installed one with a 27 hp motor powered by a RPC and there are no inrush problems because of the built in VFD and soft start feature.....

I think my bases are covered and I'm going to get it.

awww if thats the case then you should be good to go.... make sure you confirm that your older model does indeed have the soft start feature.

 

[Steve from Socal]

Now that you know what the machine needs and have a defined conversion method chosen, call your power company engineer and run it by them. Regardless of what the machine company sez the power company is the last word.

 

[cdoublejj]

a few comments on the start up amp draw. That's what capacitors are for. most smaller stuff has them. i have one the siez of shampoo bottle that will start vehicle and i don't mean a jump pack i mean small capacitor bank. now scale that up the size of a 5 gallon bucket. lol it almost sounds like this question is being asked is implying this phase perfect unit does NOT have a big capacitor.


it also sounds like phase perfect say a market as this is eevidently a common issues and they had the capital to throw teams of engineers and RnD at it.