Comparative analysis in the performance of the FH 90 squirrel cage motor using MP1015 variable frequency inverter drive and normal frequency supply

Abstract:
Three-phase electric motors are very rugged machines that have to withstand almost endless
abuse from end users and still continue to perform to specification. There are several variables
of which end user is often unaware. Many have significant effect on the general performance
of the motor like the terminal voltage and the application of various torques. In this study, the
researchers will conduct experiments in determining the performance of the FH 90 Squirrel
Cage Motor first by using the normal frequency supply, second with the use MP1015 Variable
Frequency Inverter Drive in the input terminals and third with the aid of a thermistor in the
rotor windings. In the third experiment, the researchers analyzed the effect of the temperature
in the performance of the FH 90 motor by inserting a thermistor in the rotor windings. The
performance of the FH 90 motor can be determined by plotting the performance curves in each
experiment. These are the curves of the speed, torque, ampere, temperature and voltage. Based
from the results, when running in a normal supply frequency, the speed of the FH 90 is
constant and the torque is varied to obtain the desired results. Therefore, the output power,
current and efficiency is in proportion to the speed and tends to drop off when the motor stalls.
In the second experiment, when driven using MP1015 VFID, the torque is constant and the
frequency is varied to obtain the required results. It is observe that when using the MP1015, the
torque is constant when the supply frequency is varied from 48-90 Hz this is because the ratio
of the voltage and frequency is constant throughout the experiment. In the third procedure, it is
observed that when using MP 1015 VFID in the FH 90 motor , the torque of the load is
constant and the temperature rises only from 20-30 Hz and from 80 to 90 Hz. Beyond these
values, the motor experiences a rise in temperature and thus more power losses has been
developed. But when the motor is expected to run in normal frequency supply, the FH 90
motor experiences constant rise in temperature from 0.1 N-m to 0.5 N-m. Thus, the motor must
be provided with a cooling fan to prevent it from harmful effects of overheating.