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What causes a 3600 rpm motor to appear to single phase when starterd with an ATS23 controller?

A 3600rpm or two pole motor typically has very low starting torque characteristics. This when combined with reduced voltage (e.g., an ATS23) may prevent the motor from developing enough excitation current to begin rotation.

To compensate for this, users should:
1 - Minimize the acceleration time setting. Increasing acceleration time draws out the time it takes the motor to develop rated torque. A longer time will simply aggravate the situation;
2 - Use current limit to control the ramp characteristics;
3 - Enable the Boost function. On a start command, this will apply full voltage to the motor for 5 cycles. The controller will then apply reduced voltage and ramp up. The 5 cycles is enough for the motor to develop a positive field and rotation.

This condition has also been described as appearing to single phase, to cog, or rock back and forth in direction. The condition is usually intermittant and may only occur every 3 or 4 starting attempts. By trying multiple times to start the motor, a user will typically build up enough of a field that the motor will start.

CTA-ID : 6399
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