VFD basics
What Does VFD stand for?
Variable Frequency Drive
The DC buss (capacitors)
increasing frequency does what?
Increases motor speed
What is the purpose of grounding a VFD?
To protect equipment and reduce electrical noise.
What does a VFD control in a motor?
Speed by varying frequency and voltage
What component converts DC back into a variable frequency AC output?
The inverter section (IGBTs)
Purpose of a soft start?
Reduce in rush current
Removes harmful shaft voltages and protects bearings.
Are one common application of a VFD
Pumps, fans, HVAC systems, etc
What part of the VFD protects internal circuits from electrical noise and surges?
The EMI/RFI filter
What does a PID Loop control
Pressure, flow, temp
What can happpen when Circulating shaft currents are not controlled?
Bearing fluting or premature bearing failure
What electrical components inside the VFD converts AC to DC?
The rectifier
What does and IGBT stand for?
Insulated gate Bipolar transistor.
Carrier frequency refers to?
IGPT, switching frequency
Where is a grounding ring typically installed?
Around the motor shaft near the drive- end bearing
Why do VFDs improve energy efficiency?
The match motor speed to actual load demand.
What device often sits in front of larger VFDs to reduce harmonics?
Line reactor or harmonic filter
If Hertz ratio isn’t maintained In a VFD what happens?
Motor torque is reduced or becomes unstable
What component protects motors from voltage spikes caused by long cable runs?
Sine wave filter