Title: PE 7 Phase Control
Course: 15/SP Power Electronics Theory (ELTR-2560-31) > Section: Learning Modules

Q: The main use for an SCR is as a  ____.
- amplifier
- rectifier
- filter
- inverter
A: rectifier

Q: The current flow through an SCR is controlled by ____.
- continuous gate current
- a gate voltage (current) pulse
- proper anode cathode polarity
- anode cathode minimum holding current
- all of these a-d above
- some of these b-d
A: some of these b-d

Q: A triac is _______ SCRs connected ______ parrallel.
- 2, series
- 2, anti
- 4, in
- 2, duplicate
A: 2, anti

Q: Changing voltage by changing the firing angle of SCRs is called _________ control.
- phase
- firing
- conduction
- voltage
A: phase

Q: If the firing angle is 30 then the conduction angle is ____.
- -30
- 0
- 30
- 150
A: 150

Q: An SCR is in series with a light bulb.  A firing angle of 2 would result in a ____ light while a firing angle of 170 a ____ light.
- bright, dim
- dim, bright
- bright, bright
- dim, dim
A: bright, dim

Q: A three phase recitifier (AC to DC) requires a total of _________ SCRs and\or diodes.
- 2
- 3
- 4
- 6
A: 6

Q: The method of controling average DC voltage through a SCR rectifier circuit is called____.
- controlled rectification
- solid state controlled rectification
- phase control
- DC variability
A: phase control

Q: A soft-starter or dimmer uses SCRs to control average _________ to the load (motor or light).
- DC current
- AC frequency
- AC Voltage
- DC voltage
A: AC Voltage

Q: “Excitation” means to power a coil with ______ voltage, making the coil into a magnet.
- DC
- AC
A: DC