Chapter 12 - Adjustable-Speed Drives Flashcards
Adjustable-speed drives change the output speed of an electric motor.
True
Both mechanical and electrical adjustable-speed drives are widely used in conveyor applications.
True
Adjustable-speed drives operate as closed-loop systems only.
False
Thyristors are current amplifiers that can start and stop conduction upon command.
False
Power semiconductors are used in electrical adjustable-speed drives.
True
Some belted adjustable-speed drives are with remote electrical speed adjustment and speed indicators
True
All adjustable-speed drives provide a means for starting, stopping, and adjusting the output speed of the drive.
True
A dough mixer is a typical constant-horsepower application.
True
Solid-state control techniques make step less control possible.
True
Wound-rotor drives are available in ratings from fractional hp to 40 HP.
False
Analog regulators process current and voltage signals in analog form.
True
The term “inverter” refers to equipment that produces an AC output from a DC input.
True
CSI drives regulate current rather than voltage.
True
One seldom needs to be concerned with environmental conditions when selecting adjustable-speed drives.
False
Regenerative braking provides negative torques at any speed.
True
Brushless servo-drives typically have top speeds as high as
9000 rpm
Which adjustable-speed drive type motor and control provides the slowest maximum continuous torque in lb-in.?
DC-MC; PWM
Which adjustable speed drive type motor and control provides the highest rpm speed range?
BLDC; PWM-FV
The economies of CSI drives make them attractive in ratings
Above 50 HP
A drive can be converted from a speed control to a tension control system through a
Torque control option
Traction drives are best suited for applications with
Steady loading
What do adjustable-speed drives change in an electric motor?
Output speed
What 2 types of adjustable-speed drives are widely used in conveyor applications?
Mechanical and electrical
What are ALL adjustable-speed drives capable of providing?
Means for stoping, Means for adjusting the output speed of the drive, Means for starting (all of the above)
Which of the following is a typical constant-horsepower application?
Dough Mixer
What type of drive regulates current rather than voltage?
CSI drive
Time required to reach 50% of the final value
Delay time
The motor continually searches around the desired value but never settles in.
Hunting
Time required to reach first peak overshoot.
Peak Time
Motor searches during a short period of time for the command signal and finally settles in.
Ringing
Time required to go from 10% to 90% of the final value.
Rise time
Time required to reach and stay within the allowed band of the final value.
Settling time
