Three phase dv/dt reactor improves reliability of drives and motors

The TPQDR3914 Three Phase dv/dt Reactor from EMC solutions provider EMIS  is a specially designed inductor installed at the output of a Variable Frequency Drive (VFD) or inverter to limit the rate of voltage rise (dv/dt) generated by PWM switching, reducing voltage stress and protecting motor insulation.

Modern VFDs use fast IGBTs that can create high dv/dt, voltage reflections (especially with long motor cables), increased bearing currents and EMI. Installation of a dv/dt reactor helps prevent premature motor failure, nuisance power tripping and mitigates EMI.

Designed for 0.8% impedance the reactor provides effective protection while causing a very low voltage drop and minimal power loss. The TPQDR3914 will operate reliably with modern high-frequency PWM drives, with current ratings from 4A to 500A. It reduces motor insulation stress, bearing currents, and the risk of premature motor failure while minimising  reflected wave effects in long motor cables.

• Typical applications include
  Variable Frequency Drives: dv/dt reactors limit the voltage rise from PWM outputs protecting motors from insulation stress and reducing high frequency transients
• Pumps: smooth voltage transients from dv/dt reactors prevent insulation and bearing damage in continuously running motors
• Fans and Blowers: Reduce motor voltage spikes and acoustic noise caused by fast switching in VFD driven fans and blowers
• Compressors: Mitigate high dv/dt and reflected voltage peaks that can degrade motor windings under heavy mechanical load
• Conveyors: Protects conveyor motors from insulation stress during frequent starts/stops and rapid speed changes
• HVAC Systems: Reduce electrical stress on motors in air-handling units, chillers and fans improving system reliability
• Long Motor Cables: Limit voltage overshoot and reflections that occur over extended cable runs protecting insulation and motor life
• Three-phase induction motors and old motors not designed for inverter duty.