WorksheetsAC Voltage Controller
Total questions: 26
Worksheet time: 13mins
Both AC voltage controllers and cycloconverters are the full-controlled AC-AC converters.
True
False
Choose the application of AC voltage controllers.
To control the speed of DC motors.
To control the RMS voltage of tap changing transformers.
To control the illumination of LED lighting systems.
To control the heat of industrial furnaces.
What is the specific term to describe the connection between the thyristors?
Forward parallel connection.
Inverse parallel connection.
Forward series connection.
Inverse series connection.
By using the phase angle control technique, the AC source is connected and disconnected to the load for every positive and negative half-cycles of the AC supply voltage waveform.
True
False
In a complete operation of the AC voltage controller, the AC source is turn-on and turn-off for several cycles using the integral-cycle control technique.
True
False
Based on the figure, identify the period of a complete cycle of the output current waveform.
0.04 s
0.08 s
0.12 s
0.16 s
Based on the figure, determine the duty ratio of the AC voltage controller.
0.25
0.5
0.75
1
What is the control technique used to control this AC voltage control circuit.
ON-OFF control
Bidirectional phase control
Integral control
Unidirectional phase control
Chose the correct statement about the On-Off control
The circuit used SCR and diode as a switch
The circuit can be triggered at α > 0
The circuit also known as integral control
'n' is the number off cycle during Toff
Chose the correct statement about the On-Off control
The circuit used SCR and diode as a switch
The circuit can be triggered at α > 0
The circuit also known as integral control
'n' is the number off cycle during Toff
An AC voltage controller input voltage Vs= 120V, f=500Hz. Calculate Ton, if the switch is on for 30 cycle.
60s
60ms
0.6s
0.6ms
A voltage source Vs = 240V supplies a resistive load through a bidirectional AC voltage regulator. Determine the rms output voltage, if the thyristor firing angle is fixed at 180° with respect to the supply voltage.
15V
120V
240V
0V
Select the correct waveform for bidirectional phase control.
Given the duty cycle D= 0.75 and and the total cycle is 60. Calculate the number of cycle during switch on, n:
80
45
20
50
An AC voltage control converts AC power at one input frequency to output power at a different frequency
TRUE
FALSE
Based on the waveform,
fo=21fin
fo=41fin
fo=2fin
fo=4fin
AC voltage controllers convert
fixed ac to fixed dc
variable ac to variable dc
fixed ac to variable ac
variable ac to fixed ac
The AC voltage controllers are used in __________ applications.
power generation
electric heating
conveyor belt motion
power transmission
In the principle of phase angle control
the load is on for some cycles and off for some cycles
control is achieved by adjusting the firing angle of the devices
control is achieved by adjusting the number of on off cycles
control cannot be achieved
at above, given voltage controller circuit
the positive half cycle at the load is same as the supply Vs
the negative half cycle at the load is same as the supply Vs
the positive and negative half cycles at the load are identical to the supply
none of the mentioned
In the below given voltage controller circuit
only the negative cycle can be controlled
only the positive cycle can be controlled
both the cycles can be controlled
none of the mentioned
The single phase mid-point type cycloconverter uses __________ number of SCRs.
4
8
6
none of the mentioned
The single phase bridge type cycloconverter uses __________ number of SCRs.
4
8
6
none of the mentioned
In the positive half cycle from ωt = 0 to π
P1 and P2 are forward biased
N1 and P2 are forward biased
P1 and N2 are forward biased
None of the mentioned
In the below shown circuit, the diode conducts for
90°
> 90°
< 90°
0°
The below given output voltage waveform can be obtained by a
half wave ac voltage controller
full wave ac voltage controller
half wave controller with firing angle = 0° for T
full wave controller with firing angle = 0° for both T1 and T2
