They solve different electrical problems
A transformer changes voltage and may provide isolation or a defined grounding boundary. A VFD changes the frequency and voltage supplied to a motor to control speed and torque. They may appear in the same system, but one is not a substitute for the other.
Compare the project need
| Requirement | Transformer | VFD |
|---|---|---|
| Main function | Voltage ratio or isolation | Motor speed and torque control |
| Primary load | Distribution or equipment supply | Compatible motor and driven load |
| Key inputs | kVA, voltage, vector group, impedance, grounding | Motor data, load curve, speed range, control, braking |
| Main interfaces | Switchgear, bus, protection, grounding | Motor cable, PLC, HMI, feedback, EMC |
| Common boundary | Fault, voltage drop, thermal duty | Harmonics, parameterization, cooling, commissioning |
Scope boundary
Select based on the actual system requirement and coordinate both devices when both are needed. This comparison does not approve a motor-drive or power-distribution design.
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