What is a safety consideration when working with VFD-driven motors?

• A. They pose no electrical hazards.
• B. They require no isolation.
• C. Respect stored energy and ensure proper isolation due to DC bus.
• D. They only affect speed, not torque.

Answer: (C)

Stored energy in the drive’s DC bus and the need for solid isolation are the main safety concerns when working with VFD-driven motors. The drive contains capacitors that store energy, and these can remain charged even after you remove power. If you touch terminals or open connections without properly isolating and discharging this energy, you can receive a serious shock. To stay safe, follow proper energy isolation: disconnect the drive from the power source, apply lockout/tagout, and verify that both the input lines and the DC bus are de-energized and have discharged per the manufacturer’s guidance. Be mindful that regen or backfeeding from the motor can re-energize the bus, so never assume it’s safe just because the mains are off. This emphasis on stored energy and proper isolation is the essential safety practice for working with VFD-driven motors.