The Rotary Phase Converter & Voltage Stabilizer combination is designed especially for three-phase CNC/PLC machines, including AC & DC motor drives, or any voltage-sensitive 3-phase machine operating from a single-phase power source.

Balanced Voltage Phase Output at +/- 5% voltage stabilization

230V and 460V models
For 60Hz and 50Hz use
Unit of Measure

N/A Designed especially for three-phase CNC/PLC machines, including AC & DC motor drives, or any voltage-sensitive three-phase equipment operating from single-phase power source.

Phase-A-Matic™ has been successfully providing phase converters since 1965, and for CNC machines from the time they were first introduced into service in the U.S.A.

Reliable and dependable conversion for CNC/PLC machines

Power output:
  • Provides balanced voltages necessary for dependable operation of voltage-sensitive equipment.
  • True three-phase sine wave power at 120 degree phase angle

Description of CNC PAC:
A Rotary Phase Converter, Voltage Stabilizer combination, when properly sized, provides the necessary voltage balance of close to + 5% or less between legs compared to standard three phase line voltage of + 10%. It also helps to keep the output voltage stable during peak loads, thus helping most CNC/PLC and other voltage sensitive equipment to operate properly.

Consult factory for sizing and other voltages:
Most CNC/PLC machines require a CNC PAC™ 1-1/2 to 2 times larger than the spindle motor to accommodate the extra amps for starting, instant reversing, and for the servos, hydraulics, etc.

Later model CNC/PLC machines are more technologically sophisticated, with up to 30,000+ RPM spindles, regenerative braking, etc. These may require a CNC PAC™ even larger. We have a large data bank from past applications experience to help you with these decisions.

Sizing Helps
The correct size Rotary determined first. In most cases, the Voltage Stabilizer is required to be of the same HP rating, or size. For correct sizing of the Rotary Converter:
  1. Refer to Application Notes - additionally available in PDF form as RTN.pdf.
  2. Help is also available through the Sizing Assistance page. Fill out the appropriate form and submit it to us. A qualified technician from Phase-A-Matic™, Inc. will contact you.
  3. It is best to communicate with a Phase-A-Matic™ technician for correct sizing of your CNC PAC Phase Converter. Call us at 1-800-962-6976.

Rotary Converter

Reliability, quality and construction of the Phase-A-Matic™ Rotary Phase Converter:

Baldor Electric/Phase-A-Matic™ Design and Quiet Operation
The rotary portion of our converter is proprietary, custom built to our specifications by Baldor Electric, one of the largest and most trusted motor manufacturers in the world, with warranty stations nationwide and worldwide. It is a true phase converter and not a modified electric motor as most of our competitors use. Many years of testing, changing and developing the converter in conjunction with Baldor’s engineers has produced a very simple and trouble-free converter with extremely low idle current and low noise level. Many of our customers confirm that our rotary converters are the quietest and most trouble-free available.

Simplicity of design; uses all soldered connections
Keeping the design exceptionally simple reduces the risk of electrical connection failure to almost zero since these are some of the most common causes of failure. We use only soldered connections with no mechanical electrical connections like spade clips, terminals or screws which can vibrate loose or corrode over time. There are no start capacitors, relays or contactors with connections which can come loose or arc and weld the contacts causing failure of the contactor and the start capacitors, and perhaps even the rotary converter or your equipment. Because of this we do not have circuit board failures caused by spikes generated by the magnetic contactors as some of our competitors do.

The Rotor
The Phase-A-Matic™ failure rate is practically zero because the rotors are specifically designed and manufactured for rotary converter use. [see MTBF below] However, some of our competitors emphasize that rotors often fail. This is because they machine standard electric motors, modifying and thereby weakening standard electric motor rotors, which were not originally designed to be used as a phase converter.

Testing before shipment
Every converter is performance tested before shipment and assigned a serial number. These records are kept for review if any questions should ever arise about the performance specifications.

MTBF (Mean Time Between Failure)
Failure rate (MTBF) is so low it's almost impossible to determine. We find that within the first 12 months approximately 1 in 150 might have a problem, and usually within a few weeks or months. After the first 12 months, it might be one or less in 5,000 over a 30 year period. We continue to hear of our Rotary Converters that have been in service for 25 or 30 years, and which are still working flawlessly. It could go on to do another 25 or 30 years. There is very little to go wrong with the Rotary Converter.

Warranty Repairs
The most likely warranty repair would be bearings or windings, which are very rare. This type of failure is much less than 1%, and if it is going to happen at all, most likely would occur within the first 12 months. Failures after that are extremely rare. See MTBF above.

Call Phase-A-Matic™, Inc. at 1-800-962-6976 for warranty repair stations in your area.

Voltage Stabilizer:

For use with Rotary Converter for 3-phase electronic equipment such as CNC/PLC machines, AC/DC drives, and all voltage-sensitive equipment. Provides the necessary voltage balance of close to +/- 5% or less between legs compared to standard 3-phase line voltage of +/- 10%. It also helps keep the output voltage stable during peak loads, thus helping CNC/PLC and other voltage-sensitive equipment to operate properly.

The normal operating voltage of the Rotary Phase Converter is 208-230VAC. The output voltage of the Rotary Phase Converter is normally higher than the input voltage under no load and light load conditions. In applications with high single-phase voltage (greater than 230V), the no load or light load output voltage may be excessive. Some CNC/PLC equipment will not work properly at the higher output voltage.
  • Supplied in a NEMA type 1 enclosure
  • Intended for indoor use only, but can be placed in a rain-tight enclosure for use in wet or damp applications.


CNC PAC™ Wiring Diagram

230V CNC PAC™ is 230V single-phase in and 230V three-phase out.
460V CNC PAC™ is 460V single-phase in and 460V three-phase out.

  • Intended for indoor use only, in dry locations, but can be placed in a rain-tight enclosure with ventilation for use in wet or damp locations.
  • Always use T-1 and T-2 to operate magnetic controls.
  • Also see Rotary Converter Installation Instructions for the Rotary Converter, or download the Rotary Converter and Voltage Stabilizer PDF brochure.