38
compressor at high load conditions, especially if operat-
ing below the nominal voltage.
Figure 31 shows two sample voltage curves showing
compressor motor voltage (V) versus operating speed
(Hz). As shown in the graph, the motor voltage is lowered
at lower operating speeds while maintaining a fixed Volts/
Hz value.
600
500
400
300
200
100
0
0 10 20 30 40 50 60
Frequency (Hz)
Motor Volts (V)
380V
460V
Fig. 31 — Sample Compressor Motor Voltage Curves