Phasor

Phase Converters have a diverse range of applications and are found in many sectors of society. If electric motors offer to relieve the high maintenance schedule of gas engines or they present a cost-effective alternative to your operation, then phase conversion should be your first consideration. Commitment to quality, adaptability in design, and a desire to meet the specialized needs of our customers, has lead to Willett Manufacturing becoming a leading manufacturer of Phase Converters in Canada. Willett products provide you with years of maintenance free operation.

The Phasor is a static (non-moving) phase converter. It essentially consists of an enclosure containing the "Willett Power Pack", capacitors, and relays. It is primarily designed for single motor applications. More than one motor may be operated at one time in some cases, but each application must be sized individually to prevent damage to the motor and converter. Multi-motor operation really lies within the realm of the Willett RotaDyne. The Phasor supplies an out of phase current wave by splitting a single-phase lead, thereby forming a third current path sufficient to start the motor. Once the motor is started, the Electro- magnetic field (E.M.F.) from the running motor holds a power relay open to disconnect the starting cycle and the motor continues to run on single phase power with a capacitor produced third phase. Instant reversing characteristics are maintained with a static converter. The motor rpm is not affected and most two-speed motors can be run. Starting current drain of a Phasor is about 20% comparative to the same size single-phase motor.

Sizing

Sizing the Phasor

Care must be taken when putting together a static converter/electric motor system. It must be noted that this type of system will produce two thirds of the electric motor's rated horsepower. For example, a fifteen horsepower motor coupled with a 15 horsepower Phasor will develop 10 horsepower at the shaft. Energy consumption remains equal to the supplied horsepower equivalent or 10 horsepower in this case. The Phasors horsepower rating must equal that of the electric motor. Motors operated with a static converter can have slightly less starting torque than when operated on regular three-phase power. This is a consideration when sizing the converter, particularly when the load is hard to start. To overcome hard start loads the heavy duty Phasor or the next larger size of standard Phasor-motor combination should be purchased.

Light Duty: The light duty Phasor or UY series is for applications where the number of starts and stops are infrequent. Tools operated four or five times an hour would be such an application.

Heavy Duty: The heavy duty Phasor or Y2 series is used for frequently started or jogging applications such as compressors or hoists.

The following chart provides the Model Number of the Phasor that will match the horsepower of your motor, (Remember, this matched horsepower will be derated by one third). When choosing a phase converter, Willett recommends that you call the factory with any questions about sizing or applications. There may be simple features or adjustments available that can make your converter more efficient for your application.

Horse
Power

Model Number

Light-Duty

Phasor
Heavy-Duty

Phasor

Auto-Phasor

Combination Phasor & Motor Controller

230V 460V 230V 460V 460V* 230V 460V

1-1.5

UY-115

LK-115

2-3

UY-235

LK-235

3
Y2-235
K2-235AXVS
S240CB30

4-5

UY-445

LK-455

5

Y2-455

K2-455AXVS
S480CB30

6-8

UY-608

LK-708

7.5

Y2-608

K2-608AXVS
S240DB60

8-10

LK-710

8-20

UY-710

10

Y2-710

K2-710AXVS
S240EB60 S480DB30

11-15

LK-1500

15

Y2-150

K2-150

K2-150AXVS
S240EB100 S480DB60

20

Y2-200

K2-200

KS-200AXVS
S240FC100 S480EB60

25

Y2-250

K2-250

K2-250AXVS
S240FC200

30

Y2-300

K2-300

K2-300AXVS
S240GC200 S480EB100

40

Y2-400

K2-400

K2-400AXVS
S240GC300 S480FC200

50
K2-500 S480GC200

60
K2-600

* Also available in 230 Volt.

Technical Information

Power Requirements

Power supplier transformers should have 1 KVA capacity per effective connected horsepower over and above other single-phase motors.

Inrush Currents

A Phasor unit and a three-phase motor will require approximately 350% of the full load nameplate current rating for starting. This is to be compared with inrush currents of 600% for single-phase motors. Power suppliers generally limit single-phase motors to a 10 HP maximum because of the effects to their lines during starting periods. The Phasor and three-phase motors are far more common in horsepower ratings 5 and up.

Efficiency and Power Factor

The overall efficiency of the three-phase motors run from single-phase lines with the use of a Phasor is lowered by almost a negligible amount . Small imperfect losses occur in the capacitor panels and relay coils. As compared to a three phase motor on three phase lines the Phasor/motor combination works more efficiently during starting and under normal load because of the leading power factor on start and the unity power factor under full load. This means all the metered power is truly useful power. The ratings of three-phase motors normally range in the upper 80's to lower 90% efficiency. Single-phase motor efficiencies are much lower, at 65 - 75%.

Torque

A Heavy Duty model Phasor paired with an equally sized three phase motor can exhibit only slightly less locked rotor torque for starting than the three phase motor on three-phase lines. Since the Phasor/motor combination operates at 2/3 of their rated horsepower, the starting torque is adequate for most properly sized applications. To overcome heavily loaded motors with starting problems:

Use the next size larger Phasor and corresponding three-phase motor.
If the produced phase current is below the maximum motor nameplate rating add extra running capacitors directly to the motor starter.

Select a design C or D electric motor for better starting torque characteristics since the electric motor may not have enough torque for the application.

Forward- Reverse Applications with the Phasor

One of the biggest advantages of three-phase motors over single-phase motors or gas engines is instant reversing. Simply interchange any two motor leads and the motor is reversed. Heavy-duty Phasors, Forward-Reverse switching and an appropriate sized contactor are required for this application.

Two Speed Motor Applications

Two-Winding (Two-Speed Motors) require a Phasor that is matched to the smallest horsepower rating of the motor.

With Single-Winding, Constant or Variable Torque Motors (reconnectable pole type), the smallest HP must be matched to the Phasor unit. We recommend you contact the factory when using this type, as these motors have some torque limitations and must be adapted correctly to ensure satisfactory operation. Heavy-Duty model Phasors must be used with this application.

Model Features

Standard Phasor:

The Standard Phasor consists of the "Willett Power Pack", capacitors and relays. A general-purpose enclosure (12" x 12" x 6") is used that is suitable for indoor mounting under dry conditions. Standard input/output voltages are 230 and 460 VAC.

Complete Phasor:

In addition to the features of the Standard Phasor, the Complete Phasor includes a selector, magnetic starter, and thermal overload protection.

Auto-Phasor:

The Auto-Phasor is a static converter that allows you to utilize 90% of the matched converter/motor horsepower rating. In other words, a 10 HP motor matched with a 10 HP Auto-Phasor will develop 9 HP at the motors shaft.

Combination Motor Controller/Phasor

This model includes a main disconnect, magnetic starter, stop-start or selector, provisions for remote switch, and a standard converter contained in a dust-tight or weatherproof enclosure. Alterations are available to meet customer specifications.

Special Applications:

The Phasor may be ordered for applications requiring special enclosures, as well as motor protection and control as part of the unit. A special Phasor is also built with over-current, overload and single-phase protection, complete with a lightning arrester, all in a CEMA 3 or 5 enclosure to be used on oilwell pumpjacks or irrigation systems.

Options

Enclosures:

We offer a variety of enclosures for special applications:

Oil-tight
Dust-tight
Water-tight
Weatherproof

Voltage:

600 VAC models are available on special request.

Voltage Transformers:

A transformer is also available for voltage conversion in special applications. A voltage variation of more than 10% above or below the normal rating will affect both converter and system performance.

Distributors Welcome! Contact factory for further information.

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