77801. In a 3 phase semiconverter, the firing frequency is
77802. Present day HVDC converters are all
77803. A single phase full converter gives maximum and minimum output voltage at firing angles of
77804. A thyristor has its gate current zero. To start conduction the forward voltage must exceed
77805. Assertion (A): Snubber circuit has an RC series circuit in parallel with SCRReason (R): Voltage across a capacitor can not change instantaneously.
77806. In dielectric heating, the thyristor circuits consist of
77807. On load tap changer using thyristors can have a maximum of two taps.
77808. Assertion (A): A cycloconverter may be line commutated or forced commutatedReason (R): A step up cycloconverter requires forced commutation.
77809. In the below figure the rms voltage across each half of secondary is 200 V. The peak inverse voltage across each of thyristor is
77810. Assertion (A): A GTO circuit is more compact than SCR circuit Reason (R): A GTO can be turned off by negative gate pulse.
77811. In a single phase full wave ac regulator, the firing angles in the two half cycles
77812. As regards single phase dual converter
77813. To protect an SCR against high di/dt we connect
77814. In a parallel inverter
77815. A silicon controlled switch has :
77816. 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
77817. A single phase fully controlled bridge rectifier is fed by a source having inductance. The output voltage during overlap period is
77818. In a semi converter feeding a resistive load, the firing angle is a . Each thyristor conducts for
77819. Between which points does UJT exhibit negative resistance characteristics
77820. A thyristor has maximum allowable junction temperature of 110° C and the ambient temperature is 40°C, If the maximum internal power dissipation is 50 W, the thermal resistance is
77821. A single phase electric heater uses phase controlled thyristors. The firing angle is 90°. The degree of heating is
77822. Which of these commutation methods is used in AC-DC converters?
77823. When thyristors are connected in series and parallel, it may be necessary to have :
77824. A single phase half wave regulator uses
77825. A Shockley diode can be used
77826. An SCR has a turn on time of 4 μs. The gate pulse should have a duration of about
77827. In a multiphase chopper, the different choppers operate in
77828. In a 3 phase semiconverter, the dc output voltage for a certain firing angle is 50% of the maximum possible value. The firing angle is
77829. A high frequency series inverter consists of
77830. In an SCR, the anode current consists of
77831. In the below figure, the average value of load current is 15 A. The load is highly inductive. The peak value of thyristor current is
77832. A 3 phase semiconverter when supplying a certain load has a rectification efficiency of 0.6 and transformer utilisation factor of 0.35. When a 3 phase full converter is supplying the same load
77833. Assertion (A): A high dv/dt may cause triggering of a thyristor.Reason (R): A high dv/dt results in charging current in the thyristor.
77834. Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V. Reason (R): When an SCR is conducting, the junction temperature is about 200°C.
77835. When the core of a saturable reactor is saturated, the inductance is high.
77836. In controlled heating circuits, thyristors act as
77837. In a fully controlled bridge converter feeding a resistive load the waveshapes of output voltage and output current
77838. A chopper cannot be line commutated.
77839. Natural commutation can be used in :
77840. In a thyristor the gate lead is connected to the n layer near the p layer to which anode is connected.
77841. A single phase half wave rectifier circuit has a free wheeling diode. The free wheeling diode will conduct only if
77842. McMurray Bedford full bridge inverter uses
77843. Which converter is used in HVDC transmission?
77844. Assertion (A): The turn on time of SCR is about 1 to 4 ms.Reason (R): The turn off time of SCR is about 10 to 300 ms.
77845. Which chopper circuit operates in all the 4 quadrants?
77846. A single phase cycloconverter feeds a resistance heating load. The heating power is provided by
77847. Which of these commutation methods uses an external pulse for commutation?
77848. In a single phase full wave regulator feeding an R-L load, the power factor angle of load is θ. The range of control of firing angle a is
77849. A separately excited dc motor is run from a dc source through a chopper. At 600 rpm and rated torque, the duty cycle of chopper is 0.8. At 600 rpm and half the rated torque, the duty cycle is likely to be
Terms And Service:We do not guarantee the accuracy of available data ..We Provide Information On Public Data.. Please consult an expert before using this data for commercial or personal use
Powered By:Omega Web Solutions