D Flashcards
A vfd can control the?
Torque out put
3 examples of variable torque load
Evasive fans
Pumps
Blowers
Constant torque loads
Torque remains constant as torque changes
3 examples of constant torque load are?
Compressor
Conveyer
Positive displacement pump
Open loop control runs at?
Pre set values in programming with feedback from the motor
Closed loop control runs at?
Preset values. It also has feedback from motor sensing device.
VFDs provide ramped soft start which helps?
Reduce in rush current
An induction motor runs at a speed slightly less than?
Synchronous speed
VFDs are installed for 3 basic reasons. Name them.
Energy savings
Accurate process control
Extended equipment life
Variable loads require only ___ of the power and ___ of the torque when they run at half speed.
1/8 of power
1/4 of torque
Constant torque load power requirements are ___ of the speed is 1/2
1/2
Typlically VFDs run with?
Open loop
When installing a full voltage starter for a motor the main concerns are
Horsepower
Voltage
SF
If control cables cross they must do so at an angle of?
90 degrees
VFD cables should be at least ___ away from control and signal cables
300mm
