Question

Question 2 a) A 9kW heater (Resistive Load) is powered by a DC supply unit. Rated voltage of the heater is 200V. The temperature of the heater is controlled by varying DC voltage (where, 50 V gives minimum temperature and 200 V gives maximum temperature). If AC supply voltage is 230 V, 50 Hz. (i) Sketch the circuit diagram of the rectifier for the heater. [3 marks] (ii) Show by calculation how both the 50 V and 200 V voltage levels can be obtained. [8 marks] b) A load requires a three phase full bridge uncontrolled rectifier to operate. Supply voltage to the rectifier is 400V, 50Hz. (i) Sketch the rectifier circuit diagram. (ii) Compute the load current if it is a 15kW load. [4 marks] [4 marks] (iii) One of the major problem in the rectifier circuit is failure of diode. Determine the minimum forward current and blocking voltage for the diode. [6 marks]

          Question 2
a) A 9kW heater (Resistive Load) is powered by a DC supply unit. Rated voltage of the
heater is 200V. The temperature of the heater is controlled by varying DC voltage (where,
50 V gives minimum temperature and 200 V gives maximum temperature). If AC supply
voltage is 230 V, 50 Hz.
(i) Sketch the circuit diagram of the rectifier for the heater.
[3 marks]
(ii) Show by calculation how both the 50 V and 200 V voltage levels can be obtained.
[8 marks]
b) A load requires a three phase full bridge uncontrolled rectifier to operate. Supply voltage
to the rectifier is 400V, 50Hz.
(i) Sketch the rectifier circuit diagram.
(ii) Compute the load current if it is a 15kW load.
[4 marks]
[4 marks]
(iii) One of the major problem in the rectifier circuit is failure of diode. Determine the
minimum forward current and blocking voltage for the diode.
[6 marks]

Question 2
a) A 9kW heater (Resistive Load) is powered by a DC supply unit. Rated voltage of the
heater is 200V. The temperature of the heater is controlled by varying DC voltage (where,
50 V gives minimum temperature and 200 V gives maximum temperature). If AC supply
voltage is 230 V, 50 Hz.
(i) Sketch the circuit diagram of the rectifier for the heater.
[3 marks]
(ii) Show by calculation how both the 50 V and 200 V voltage levels can be obtained.
[8 marks]
b) A load requires a three phase full bridge uncontrolled rectifier to operate. Supply voltage
to the rectifier is 400V, 50Hz.
(i) Sketch the rectifier circuit diagram.
(ii) Compute the load current if it is a 15kW load.
[4 marks]
[4 marks]
(iii) One of the major problem in the rectifier circuit is failure of diode. Determine the
minimum forward current and blocking voltage for the diode.
[6 marks]

Added by Catalina M.

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