Static Phase Converters

Static Phase Converters


What is the ADD-A-PHASE® power converter?

It is a static converter capable of producing symmetrical three-phase currents from a single-phase source. The name ADD-A-PHASE implies that a phase is added to the already present single phase, accomplished by an autotransformer and a capacitor bank along with the motor’s impedance. Through this combination, a third phase is introduced whose relation to the other two comprises symmetrical three-phase. The motor can then operate as if it were connected to a three-phase power line.

What horsepower ratings are available with ADD-A-PHASE?

Standard types are available from HP1 through 100 HP. Units up to 150 HP have been constructed. Where high horsepower loads are to be operated, consult the power supplier to determine whether the single-phase line capacity is sufficient to carry the load.

What are typical applications?

ADD-A-PHASE has been successfully applied to operate motors on many different kinds of equipment. Some of the principle applications are pumps, fans, valve actuators, oil pump jacks, and piston type compressors.

What motor speeds can be satisfactorily operated with the standard ADD-A-PHASE, Type 2S?

Speeds of 3,600 RPM and 1,800 RPM can be operated from the standard units. For speeds below 1,200 RPM, the ECONO-PHASE® Shifter may be a better choice, depending on the motor’s power factor.

Are special ADD-A-PHASE models available?

Yes. Consult the factory for details.

Is ADD-A-PHASE available for 120 V operation?

No. 120 V input unit is not available.

Is ADD-A-PHASE available for 50 cycle, as well as 60 cycle?

Yes. The basic ADD-A-PHASE types are designed for 60 cycle, but 50 cycle units are available. Again, consult the factory for prices and delivery.

Is ADD-A-PHASE available for 480 V or 575 V operation?

Yes. The units for 480 V are catalogued, but the factory should be consulted for 575 V operation.

Can ADD-A-PHASE operate an air conditioner?

Yes. Most air conditioners can be operated with the Type 2SAC. Note that any additional three-phase motors, like evaporator fan motors, units require Type K-Duo for multiple-motor operation.

Can ADD-A-PHASE be applied to submersible pumps?

Yes. It is necessary to check the full load amp rating of the motor. If the FLA of the submersible motor is higher than a standard NEMA motor FLA of the equivalent horsepower, Type SUB should be used.

Can 480V three-phase motors be operated from a 240 V single-phase line?

Because of voltage drop, wiring size, starter size, etc., it may be desirable to operate large motors, submersible pumps, etc., at 480V when only 240V single-phase is available; the Type “3” ADD-A-PHASE is designed for these applications. Other special voltages are also available such as 240 in/208 out. Consult the factory for pricing and specifics.

How does ADD-A-PHASE benefit the utility?

The ADD-A-PHASE draws close to unity power factor while the motor is starting and running, resulting in lower line current and lower losses in line voltage. The inrush current of the ADD-A-PHASE and three-phase motor is only 3 to 4 times the running current.

Will a three-phase motor produce 100% rated power when operated through the ADD-A-PHASE?

Yes. ADD-A-PHASE is the only static converter for which this is possible, due to its autotransformer design. In fact, continuous overload (service factor) operation is available that equals the permissible overload of the average three-phase motor (1.15).

Note: while this operation is possible, some motor manufacturers (notably submersible pump motor manufacturers) may not warranty their motors if it is operated into its service factor range while powered by a phase converter. In practice, it is best to avoid service factor operation if possible to assure normal life expectancy of equipment.

Can ADD-A-PHASE operate a motor larger than the rating of the converter?

It is not recommended; however, there may be applications where the load of the motor is reduced and within the rating of the converter. Extreme caution should be observed, and it is advisable to contact the factory before attempting such an operation.

Can ADD-A-PHASE operate motors smaller than the rating of the converter?

Yes. The design of the autotransformer converter permits a smaller motor to be operated with capacitor adjustments.

Can more than one motor be operated from a single ADD-A-PHASE?

Type K-Duo ADD-A-PHASE is designed specifically for independent or simultaneous operation of two motors. Special models are also available for other multiple motor applications. Consult the factory for recommendations.

Can two speed motors be operated satisfactorily?

Ronk offers converters to operate two-speed applications. Type K-Duo or Type AA ADD-A-PHASE can be used for some two-speed motors. Consult the factory for recommendations.

Is ADD-A-PHASE also suitable for outdoor installations?

Although ADD-A-PHASE is primarily designed for indoor installation, the louvered enclosure is drip proof and may be mounted outdoors.

Can ADD-A-PHASE be installed in damp underground locations?

Yes. An example would be the many satisfactory applications in underground sewage lift stations.

Is ADD-A-PHASE available in an explosion-proof enclosure?

No. Normal heat rise of components requires sufficient cooling, one of the factors which has made the explosion-proof case impractical.

What is the life expectancy of ADD-A-PHASE?

The components selected and manufactured for the ADD-A-PHASE have a lifespan comparable to that of the average three-phase motor. Long life and reduced maintenance are among the many advantages of the ADD-A-PHASE over the conventional single-phase motor.

What is the need and availability of replacement parts?

The ADD-A-PHASE, being a static device with only a few moving parts, is relatively free of maintenance. Should replacement parts be necessary, immediate shipment can be made from factory stocks, or they can be readily acquired from local sources.

What is the ADD-A-PHASE warranty?

ADD-A-PHASE is warranted to be free from defects in material and workmanship under normal use and service for a period of one year from date of installation or 18 months from original date of shipment. A postpaid warranty validation card is supplied with each unit, which must be filled out and returned to the factory within 15 days of installation to validate warranty.



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