Toshiba VT130G1 - Manual (Page 12)

Section 3
Applications
VTISOGI provides a high quality output voltage and current, but it is not a perfect sine wave.
Therefore some increase in motor temperature, noise, and vibration may be noticed.
Special considerations must be taken when applying an inverter to an existing motor. At
slower speeds, cooling is not effective due to reduced fan RPM. FULL LOAD torque at slow
speeds may damage the motor due to overheating. In situations where the toad requires
high torque at slow speeds, the motor may require replacement with a large frame size
for heat dissipation.
Figure 3-7 shows a curve plotting acceptable torque vs. speed.
H MOTOR
Note that for a safety margin, the torque
curve shows no more than 90%
motor rated torque at any speed.
If torque requirements at slow
speeds continuously exceed levels
shown in Figure 3-7, a larger motor
can be substituted.
FIGURE 3-7
Fixed speed machinery may not run properly at available speed ranges. Operation above
60 HZ may damage bearings or rotating parts. Slow speeds may provide insufficient lubrica­
tion on oil filled gear boxes or speed reducers. Manufacturer specifications may need to
be consulted.
The above precautions should be looked at carefully to prevent any problems. It is most
often the case, however, that the motor or motors on a variable speed application can be
directly applied to the VT130G1.
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