The Impact of Variable Frequency Drives (Frequency Inverters) (part 12)
Continued from this article: The Impact of Variable Frequency Drives (Frequency Inverters) (part 11).
Figure 5, Motor losses in waveform harmonic content
| HP | Power Type | Frequency (Hz) | Percent Speed | Percent torque | Current (amp) | Temp ride(C) | Remarks |
| 10 | Sine | 60 | 100 | 100 | 12.0 | 51 | Line power |
| 10 | VFD | 60 | 100 | 100 | 12.5 | 55 | Full Load & speed |
| 50 | Sine | 60 | 100 | 100 | 59.1 | 62 | Line power |
| 50 | VFD | 60 | 100 | 100 | 61.4 | 73 | Full Load & speed |
For 10 hp and 50 hp motors operating on current which is supplied by variable frequency drive (VFD) at full speed and load (see Figure 5 above,), the current (amps) is about 4% higher than if the motors operated on line power. These increased currents cause increased temperatures in both motors.
To compensate for this extra motor heat, consider derating a 1.15 service factor motor to a 1.0 service factor when operating on VDF power.
When you select the variable frequency drives (VFDs, AC drives), don't forget to consider the potential problems of more motor noise and higher motor temperatures. But variable-frequency drives (AC drives) can play important roles in systems aimed at saving energy and improving process control. The drives also prolong the lifetime of the machines. These are the reasons we choose VFDs to apply!
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Powtran Technology Co., Ltd. (Shenzhen POWTRAN Technology Co., Ltd., DaLian Powtran Technology Co., Ltd.)
