Motor Characteristics
Listed below are some variable speed AC motor control concepts with which the user of the H9 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 H9 ASD. Autotuning is a function of the H9 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 ASD to
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 H9 ASD uses a sinusoidal Pulse Width Modulation (PWM) control system. The output current waveform generated by the 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 an ASD, rather than directly from commercial power.
Low Speed Operation
Operating a
When the motor is to be operated at low speed (less than 50% of full speed) and at the rated torque continuously, a Toshiba VF motor (designed for use in conjunction with an ASD) is recommended.
Overload Protection Adjustment
The H9 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 ASD at the factory. This setting will have to be adjusted to match the rating of the motor with which the ASD is to be used. To change the overload reference level, see Motor Overload Protection Level 1 on pg. 182.
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.
10 | H9 ASD Installation and Operation Manual |
