Static Phase Converters

Understanding how a static phase converter works is key to making the best phase converter selection for your application.

Static Phase Converters v. TEMCo Phase Converters

The following table illustrates the major differences between static phase converters and TEMCo phase converters. This information is based on laboratory testing, along with years of field experience. It is accurate across all manufacturers of static phase converters.

Feature	Static Phase Converter	TEMCo Phase Converter
Full Motor HP at Startup	Yes	Yes
Full Motor HP While Running	No, 1/2 to 2/3 HP	Yes, Full HP
Run Delta or Wye Motors	No, Wye ONLY	Yes, Delta & Wye
Power 3-Phase CNC Machines	No	Yes
Power 3-Phase Battery Charger	No	Yes
Power 3-Phase Laser	No	Yes
Power 3-Phase Oven	No	Yes
Provides Balanced Power	No	Yes
Safe on 3-Phase Circuits	No	Yes
Cost of Ownership	Higher Cost Over Time	Lower Cost Over Time
Safe for motor loads that will  be within 2/3 to full HP?	No. Will stall and burn out motor.	Yes, safe.
Converter Operational Life	Short	Long, 75-100 times longer compared to static.

How Static Phase Converters Work

Static Phase Converters do not produce continuous three phase power. Upon motor startup, static phase converters produce a third line which it supplies to the motor. So, during startup, the motor actually does receive three phase power. Once started and rotating at full speed, it stops supplying three phase power to the motor, and only supplies the single phase utility power. With the loss of two phases comes the loss in HP. Although the motor sustains rotation, if a load greater than 2/3 of the motors nameplate HP is applied, the motor may stall and will overheat. Over a period of time the motor will become severely imbalanced, and eventually burn out.

Static Phase Converters only work with single motor loads. They can not operate any equipment that requires true three phase power. Some examples of these types of equipment are:

• CNC Machines
• Welders
• Injection Molders
• Battery Chargers
• Power Supplies
• UPS's

The illustration below shows a typical static phase converter wiring diagram.



As you can see, T1 & T2 come from the single phase supply. The converter does nothing to these lines, and passes them straight through. During startup, the static phase converter generates T3. It is engaged for approximately 1 second, which allows the motor to come up to speed. T3 then drops out, and only T1 & T2 remain supplied to the motor. T1 & T2 span across two windings, which results in the motor only being able to produce 2/3 HP capacity. With a TEMCo rotary phase converter, the T3 output is continuous. This allows the connection of any type of three phase load. Three phase induction motors used in conjunction with a TEMCo phase converter will develop full nameplate HP and torque.