static phase coverters....

[ultramegabob]

I havent used one in several years, but I have a customer with a couple pieces of equipment that needs connected, is there any problem with running 2 machines on one static phase converter, or should each piece of equipment have its own? I would like to use one coverter sized for both machines, set a small breaker panel and feed the machines from there.

 

[ohm]

I havent used one in several years, but I have a customer with a couple pieces of equipment that needs connected, is there any problem with running 2 machines on one static phase converter, or should each piece of equipment have its own? I would like to use one coverter sized for both machines, set a small breaker panel and feed the machines from there.

I've done what you've suggested and it works fine.

I believe doing so also stabilizes the circuit and helps ride through dips & surges with high inertia loads due to the flywheel effect.

 

[Besoeker]

I havent used one in several years, but I have a customer with a couple pieces of equipment that needs connected, is there any problem with running 2 machines on one static phase converter

I'm not familiar with static phase converters.
Do you perhaps mean frequency converter?

 

[Rick Christopherson]

A static converter is nothing more than a motor starter that gets the motor spinning and then cuts out, leaving the motor to run on single-phase power. The exception to this is when the converter also has run capacitors which are tuned to the specific motor.

No, you can't run two machines from the same static converter, unless only one motor runs at a time and they are the same size. Actually, if you add the run capacitors to both motors, then the static converter will start the first motor, and the running motor might act as a pseudo-rotary converter for the second motor.

A rotary converter can operate more than one motor. If these are smaller motors, you might consider using a VFD instead.

 

[ultramegabob]

after doing a google I found this company, I think I will buy a converter for each machine, they are pretty reasonable...

http://www.phoenixphaseconverters.com/product.php?id_product=17

 

[peter d]

after doing a google I found this company, I think I will buy a converter for each machine, they are pretty reasonable...

http://www.phoenixphaseconverters.com/product.php?id_product=17

DO NOT buy one from Phoenix phase converters. They are poorly made and their tech support is bad.

Go with a Phase A Matic instead.

 

[Besoeker]

A static converter is nothing more than a motor starter that gets the motor spinning and then cuts out, leaving the motor to run on single-phase power.

So it is converting what to what?

 

[ultramegabob]

So it is converting what to what?

single phase to three phase, I am not really sure how they work, I dont use them very often...

 

[ultramegabob]

DO NOT buy one from Phoenix phase converters. They are poorly made and their tech support is bad.

Go with a Phase A Matic instead.

what kind of experience did you have with phoenix?

 

[Rick Christopherson]

So it is converting what to what?

In my opinion, a static converter should not be called a converter (unless it has run caps), because it really doesn't convert anything. The start capacitors provide enough of a phase shift to the third leg to get the motor started, and then the capacitors are dropped out of the circuit. Another way of looking at it is an "electronic pull string" to get the motor up to speed.

 

[norcal]

DO NOT buy one from Phoenix phase converters. They are poorly made and their tech support is bad.

Go with a Phase A Matic instead.

I second that, buy something other then Phoenix.

 

[peter d]

what kind of experience did you have with phoenix?

Loose connections, cap exploded, bad tech support.

 

[JacksonburgFarmer]

From my experiance....I vote for the rotary convertor....if you get a big enough one....you can run a lot of HP.....I mean a lot. Static convertor turns your current motor into a phase convertor, and runs it at a reduced rating....sometimes ok....sometimes not....phase a matic is good, so is ARCO, Buffington from Plymouth Indiana....kinda iffy....hit and miss on quality....just my opinion and experiances...

 

[Besoeker]

In my opinion, a static converter should not be called a converter (unless it has run caps), because it really doesn't convert anything. The start capacitors provide enough of a phase shift to the third leg to get the motor started, and then the capacitors are dropped out of the circuit. Another way of looking at it is an "electronic pull string" to get the motor up to speed.

Ah, I'd have called that a capacitor start motor. I've seen a few with a centrifugal switch to take the C out of circuit once the motor is spinning.
I have never heard it being called a converter.

 

[don_resqcapt19]

A static converter is nothing more than a motor starter that gets the motor spinning and then cuts out, leaving the motor to run on single-phase power. The exception to this is when the converter also has run capacitors which are tuned to the specific motor.
...

Rick,
That is not what one of the major suppliers of this type of equipment says.

 

[e57]

I was looking at some a while back that are a full blown 3 phase invertor circuit, with 120 offset 3 phase output, much like the output of an industrial UPS.

But if serving a number of motors... Go for a larger than needed rotary. Odds are they may have plans to buy more equipment they don't have the right power for - which is why you're even thinking of it.

 

[Rick Christopherson]

Rick,
That is not what one of the major suppliers of this type of equipment says.

That's because Add-a-Phase is a balanced static converter, and it is balanced for the specific motor. If you look at the picture on the front of their brochure, you will see the start capacitors to the right and the run capacitors to the left (the round, black ones). I never said that all converters were only starters, and if you go back and read my postings, you will see I repeated the comment that if they had run caps, then they were different.

The easiest way to identify a converter without run caps is when they rate one model to support a broad range of motors, such as 3 to 5 hp for the same unit. When all they are doing is starting the motor, then oversizing the start-cap circuit will still get the motor spinning, and that is why these models span several motor sizes for each size converter.

The Add-a-Phase is somewhat unique in that most static converter designs don't employ an induction coil (autotransformer) to further balance the phases. I don't know what their prices are like, but with the way they worded it in the brochure, it sounds like the Add-a-phase is more expensive than a rotary converter.

 

[don_resqcapt19]

Rick,
If the converter doesn't supply some form of the third phase, how much do you have to derate the motor? Three phase motors don't like missing phases, even after they are up to speed.

 

[Rick Christopherson]

Rick,
If the converter doesn't supply some form of the third phase, how much do you have to derate the motor? Three phase motors don't like missing phases, even after they are up to speed.

You're right. Single-phasing a 3-phase motor does not make the motor very happy.

As for derating the motor, the often repeated value is 2/3 power, but I am not convinced that this is correct. I don't have a strong enough background in motors to go through the calculations, but I would speculate that it is actually less than 1/2. You have one winding with full power and two windings with half power, except these two windings don't have the appropriate phase shift, and it leaves me wondering if their magnetic field isn't going to oppose the rotation of the motor and reduce the power even further.