Variable Frequency Drives

Variable Frequency Drives• Where we use them

• Why we use them

• Precautions

Where We use themVariable Frequency Drives (VFDs) are used for motor control in various system applications including:

• AHU Supply Fans

• AHU Return Fans

• Hot Water Pumps

• Chill Water Pumps

• Cooling Towers

• Chillers

Why we use them• Slower startup of large motors

• Speed control of motors

• Reduce maintenance cost

• Energy efficient

Precautions• ***ELECTRICAL POWER CAN REMAIN IN

VFD SYSTEM EVEN AFTER DISCNNECT IS SWITCHED OFF*** http://www.youtube.com/watch?v=pagfHf1-etw

• Running VFDs in HAND can cause system issues and damage equipment

• Voltmeters and Amp Meters will not give accurate readings of voltage and current from a VFD.

Questions?