In a dual converter both converters work as rectifiers.
One operators as rectifier and the other as inverter.
A single phase full wave regulator feeds RL load. The best gating signal is
To ensure proper triggering pulse train in necessary because load is R  L.
A 3 phase induction motor is fed by a 3 phase ac regulator to change the stator voltage. The variation in speed will be more if
If load torque is constant, the change in speed is very small.
A cycloconverter cannot give a frequency higher than input frequency.
Step up cycloconverter can give a frequency higher than input frequency.
A thyristor has internal power dissipation of 40W and is operated at an ambient temperature of 20ºC. If thermal resistance is 1.6º C/W, the junction temperature is
.
A single phase half wave converter is used to charge a battery of 50 V. The thyristor is continuously fired by dc signal. Input voltage is v = V_{m} sin ωt. The thyristor will conduct
Thyristor can conduct only when it is forward biased. This occurs only when v > 50 V.
The symbol in figure is for
In a 3 phase semiconverter, the firing frequency is
Since the circuit has 3 thyristors, firing frequency is three times the line frequency.
A thyristor has its gate current zero. To start conduction the forward voltage must exceed
With zero gate current, conduction can be started only if forward voltage exceeds breakover voltage.
On load tap changer using thyristors can have a maximum of two taps.
Any number of taps are possible.
Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR
Reason (R): Voltage across a capacitor can not change instantaneously.
Since voltage across capacitor cannot change instantaneously it protects SCR against high .
In dielectric heating, the thyristor circuits consist of
Input ac is rectified and then converted to high frequency ac.
Assertion (A): A cycloconverter may be line commutated or forced commutated
Reason (R): A step up cycloconverter requires forced commutation.
In the below figure the rms voltage across each half of secondary is 200 V. The peak inverse voltage across each of thyristor is
PIV = 2(2 x 200).
Assertion (A): A GTO circuit is more compact than SCR circuit
Reason (R): A GTO can be turned off by negative gate pulse.
Since commutation circuit is not required, GTO circuit is compact.
In a single phase full bridge converter (B  2 connection), the input voltage is v = V_{m} sin ωt. The output dc voltage for resistive load
SCRs conduct from a to p in each half cycle.
In a single phase full wave ac regulator, the firing angles in the two half cycles
As regards single phase dual converter
To protect an SCR against high di/dt we connect
current through inductance cannot change instantaneously.
In a parallel inverter
A silicon controlled switch has :
Anode, cathode, anode gate and cathode gate.
A dc chopper V = 500 V feeds an electric fraction dc series motor. The chopping frequency is 400 Hz. The series inductance required to limit the maximum current swing to 10 A is
.
A single phase fully controlled bridge rectifier is fed by a source having inductance. The output voltage during overlap period is
During the period of overlap all the four thyristors conduct and load is effectively shortcircuited. Output voltage is zero.
In a semi converter feeding a resistive load, the firing angle is a. Each thyristor conducts for
The conduction is from a to p.
Between which points does UJT exhibit negative resistance characteristics
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