|Manufacturer||Emerson U. S.|
|Motor Type||Premium Efficient, 460v|
|Desc||TEFC vertical hollow shaft|
A custom circuit changes this three-phase motor into a high-performance single-phase motor. The patented Smith PhaseAble® control has a single-phase 2-pole circuit breaker, start contactor, run contactor, start capacitor bank, and run capacitor bank. The PhaseAble® control injects currents into the motor windings so that the motor has the same full-load high efficiency from a single-phase supply that it would have on a 3-phase supply.
Using a Smith PhaseAble® controller, any 3-phase motor less than 175 HP is enabled to run from a single-phase supply with the same full-load efficiency that it would have on a three-phase supply, and with reduced starting current. Every new product needing a single-phase motor can use instead a 3-phase motor with a Smith PhaseAble® control, with lower electricity bills and lower line currents because of higher efficiency and improved line power-factor.
There are no power electronic devices in the Smith PhaseAble® controls. During normal operation supplying a shaft load, there are no current spikes or switching operation as in Adjustable Speed Drive. Consequently the current and voltage harmonics are very low. In many cases, the Smith PhaseAble® capacitors "short out" the power company voltage harmonics created by neighboring electronic loads, so that the power quality when the Smith motor is running is superior to the power quality when the motor is turned off.
During starting this is a unity-power-factor motor, which is a minimum-current motor, yielding maximum torque per unit of line current. In performance, this motor acts like a resistance load in parallel with a power-factor-compensation capacitor bank.
The "Phase-Able®" circuits create "Free-Wheeling Magnetic Flux" in the motor air gaps. This flux is rotating synchronously smoothly with almost constant magnitude. The interaction between this magnetic flux and the currents injected into the windings produces the desired shaft torque. The performance with a single-phase supply is superior to the performance on a three-phase supply. Three-phase unbalanced supply voltages on the motor terminals can distort the flux distributions so that they are not "free-wheeling", and the shaft torques can be correspondingly reduced.
The "Enabler®" supplies two motor terminals directly from the single-phase power line. At rated speed, the geometry of the windings creates a rotating magnetic flux field in the air-gap. This flux field generates a voltage which appears on the third motor terminal. This voltage appears even when the third terminal is open. When there is a current into or out of this third terminal, the voltage changes slightly.
The run-capacitor circuit connected to this third terminal injects a current which is proportional to the capacitance and an almost constant voltage difference. This is almost a constant current. When this injected current is the full-load current at the correct full-load phasor angle, then when the shaft torque is the rated value, all of the windings carry the same current magnitudes at the same power-factors. All of the currents and all of the terminal voltages