10 P9 ASD Installation and Operation Manual
Motor Characteristics
Listed below are some variable speed AC motor control concepts with which the user of the
P9 Adjustable Speed Drive should become familiar.
Motor Autotuning
Motor production methods may cause minor differences in the motor operation. The negative effects of
these differences may be minimized by using the Autotune feature of the P9 ASD. Autotuning is a
function of the P9 ASD that measures several parameters of the connected motor and places these
readings in a stored table. The software uses the information in the table to help optimize the response of
the P9 ASD to application-specific load and operational requirements. The Autotuning function may be
enabled for automatic tuning, configured manually at F400, or disabled.
The measured parameters include the rotor resistance, the stator resistance, the required excitation
inductance, rotational inertia values, and leakage inductance values.
Pulse Width Modulation Operation
The P9 ASD uses sinusoidal Pulse Width Modulation (PWM) control. The output current waveform
generated by the P9 ASD approaches that of a perfect sine wave; however, the output waveform is
slightly distorted. For this reason, the motor may produce more heat, noise, and vibration when operated
by a P9 ASD, rather than directly from commercial power.
Low-Speed Operation
Operating a general-purpose motor at lower speeds may cause a decrease in the cooling ability of the
motor. Reducing the torque requirement of the motor at lower speeds will decrease the generated heat at
lower speeds.
When the motor is to be operated at low speed (less than 50% of full speed) and at the rated torque
continuously, a TIC VF motor (designed for use in conjunction with an ASD) is recommended.
Overload Protection Adjustment
The P9 ASD software monitors the output current of the system and determines when an overload
condition occurs. The overload current level is a percentage of the rating of the motor. This function
protects the motor from overload.
The default setting for the overload detection circuit is set to the maximum rated current of the P9 ASD at
the factory. This setting will have to be adjusted to match the rating of the motor with which the P9 ASD
is to be used. To change the overload reference level, see Motor Overload Protection Level 1 on pg. 194.
Operation Above 60 Hz
A motor produces more noise and vibration when it is operated at frequencies above 60 Hz. Also, when
operating a motor above 60 Hz, the rated limit of the motor or its bearings may be exceeded; this may void
the motor warranty.
Contact the motor manufacturer for additional information before operating the motor above 60 Hz.
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