Download the NEW Synchronous Motor Catalog

These motors offer substantial advantages in applications needing their very unique capabilities.

Superior Electric synchronous motors are high pole count motors that naturally turn at slower speeds (72 or 60 rpm). They only need a resistor – capacitor (RC) network to operate from single-phase AC utility power. For loads that operate at 72 RPM or slower, they are very cost effective and simple to use. Other motor technologies (induction, DC, servo and step motors) either need gear reducers, or electronic drives to match the speed of Superior Electric synchronous motors. The cost of just the gear reduction or the cost of the electronic drive will usually exceed the total cost of the Superior Electric synchronous motor. For even slower speeds planetary gear reducers are offered. Superior Electric synchronous motors produce very low speeds with only modest gear reductions.

Performance Features

• 72 rpm motor speed (with 60 Hz voltage)
• 60 rpm motor speed (with 50 Hz voltage)
• Constant speed does not vary with the load
• 120 volt or 240 volt AC models
• Torques: 70 to 1,500 oz-in (50-1,069 N-cm)
• Gear reducers with ratios up to 125:1 and torques up to 5,000 oz-in (3,670 N-cm)
• UL and CE hazardous duty versions
• Fast starting, stopping, or reversing
• Can be stalled indefinitely without overheating

Typical Applications

Due to their ease of use and inherent slow speeds, Superior Electric synchronous motors are used in a wide variety of applications including:

• Stirring
• Valve operation
• Metering pumps
• Cryogenic pumps
• Simple position & process controls
• Linear actuators
• Edge guides
• Variable transformers
• Dampers
• Conveyor systems
• Table lifts
• Remote control of switches, antennas, etc.

Synchronous Motor Characteristics

Starting and Stopping
Rapid starting, stopping and reversing are among the advantages of Superior Electric synchronous motors. The motors will start within 1-1/2 cycles of the applied frequency and will stop within 5°. As shown in the typical starting curve, these motors will start and reach its full synchronous speed within 5 to 25 milliseconds.

Typical Starting Characteristics for a 72 rpm Motor

Phase-Shifting Network

The KS series and hazardous duty motors use a two-phase winding design. They are usually operated from single-phase AC power using a phase shifting network consisting of one or two resistors and a capacitor. These motors can also be operated directly from a two-phase power source.

The SS240 – SS450 series use a three phase winding design. They can be driven directly from three-phase voltage or can be operated from single-phase power using only a phase shifting capacitor. Ratings and part numbers for the phase-shifting components are shown in the motor charts. Detailed phase shifting component
information is given on page 17. Be sure to select the correct components for the frequency of the AC power source, since the components needed for 50 hertz operation may be different from those required for operation at 60 hertz.

Temperature

All Superior AC synchronous motors are rated for continuous duty at a maximum ambient temperature of 40°C (104°F). Motor shell temperature must not be allowed to exceed 100°C (212°F) measured with a thermocouple. The minimum ambient temperature at which the motors may be operated is -40°C (-40°F).

Starting and Running Current

It is not necessary to consider high starting currents when designing a control system for a Superior Synchronous motor, since starting and operating current are, for all practical purposes,
identical.

Stalling

If a motor becomes stalled, it will not overheat and will continue to draw only rated current. However, if the motor is stalled by running up against a stop, it will vibrate against the stop. Operating the motor continuously in this manner may eventually cause bearing failure.

Torque Versus Voltage

As indicated in the curve, the torque output of a Superior motor is approximately proportional to the applied input voltage. For intermittent operation, this characteristic can be used to provide increased torque by increasing the voltage. For example, assume that an application has a torque requirement of 200 ounce-inches (141 N-cm). Normally, a 240 ounce-inch (169 N-cm) Superior motor would be adequate, but this application is subject to wide voltage fluctuations and, therefore, the 40 ounce-inch (28 N-cm) safety margin may be insufficient. The recommended practice is to use a motor having a higher torque rating. However, a larger motor may not fit in the available space. In this case, a step-up transformer could be used to increase the voltage to the 240 ounceinch motor by approximately 10%. Because operation at a higher voltage will cause a greater temperature rise, care must be taken to assure motor shell temperature does not exceed 100°C (212°F).

Typical Torque Versus Voltage for a Superior Motor

For more detailed information please see the Synchronous Motor Catalog.

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