AC Drives and EMI/RFI Mitigation
Ferrite cores, EMI filters, drive isolation transformers, insulated power cables, and proper grounding techniques are presented as solutions to EMI/RFI.
AC Drives and Radiated and Conducted Emissions
Electromagnetic Compatibility Filters and Common Mode Chokes
Variable Frequency Drives: Source Impedance, Short Circuit Capacity, and Line Reactors
Harmonic frequency currents generated by low horse-power rated VFDs will interact with a power source of low impedance. The resulting current flow may damage the drive’s power devices.
Short Circuit Capacity: Basic Calculations and Transformer Sizing
A simplified method of calculation will allow a facility engineer or electrician the ability to estimate short circuit capacity. The application examples utilize transformer sizing for motor loads.
Variable Frequency Drives: Motor Regeneration, Overhauling Loads, and Starting Into a Rotating Motor
Many specifications call for a drive that will re-start when the driven motor is still spinning. Techniques employed by drives are presented. In nearly all HVAC applications, it is not necessary to “catch a spinning motor.” Allowing the motor to coast to a stop before re-starting may provide a lower cost solution.
VFD Ride-Through On Sag and Outage
Several techniques for ride-through on power outage are presented.
Sag Correction for Small Equipment Without Using UPS Systems
Techniques are given that will allow for ride-through without the requirement of batteries and the maintenance associated with batteries.
Transient Voltage Surge Protection
Fundamentals of surge protection are presented including suppressor ratings and lead length effects.
Generators: Standby and Co-generation
Some problems may occur when drives and UPS systems are operated from generator power.
TVSS and Energy Savings?
One manufacturer of transient voltage surge suppressors is guaranteeing energy savings as a result of transient suppression. An electric utility company questions the claim.