Power Grid Company of Bangladesh Exam -2014
Assistant Electrical Engineer
Full Marks- 100 Written Question
Answer any six Questions (Question no.8 is compulsory)
1.(a)Make a comparison between synchronous and induction motors.
(b)Enumerate and explain at least two applications of a synchronous motor
2.(a)what are the disadvantages of low power factor and what are the ways to correct it.
(b) A factory takes the following balanced load from a 440V,3-phase,50HZ supply;
i)a lighting load a 20KW
ii)a continuous motor load of 30KVA at 0.5Pf lagging Calculate the KVA rating of the capacitor bank required to improve the power factor of loads (a) and (b) together to unity.What is the new overall Pf is switched on.
3.(a)What are the different between a current transformer and a potential transformer?
(b)Draw phasor diagram of a potential transformer and discuss the causes of ratio error and phase angle error.
4.(a)Explain the principle of operation of a three phase power transformer.
(b)Assuming that two transformer having unequal ratios of transformation are connected is paralleled,indicate how the total load divides between them.
(c) What should be the KVA rating of each transformer is a V-V bank when the three phase balanced,load is 40 KVA?If a third similar transformer is connected for operation in delta-delta,what is the rated capacity?What percentage increase is effected in this way?
5.(a)Give a brief description different kind of generation in BPDB system.
(b)What is demand side of management, how can we reduce generation shortfall by adopting such management?
6.Write short note on any three of the following:
a) Transmission line protection
b) Reveres power relay
c) Gas Turbine Power Plant
d)SF6 circuit breaker
e)Ripple factor respect of rectifier output.
7.(a)State the benefits which are derived from the application of shunt capacitor on the load end of a circuit supplying a load of lagging power factor.
(b)Draw a comparison between shunt capacitor and synchronous condenser in respect of their application power system.
8.(a)Write short assay on “private sector participation in power generation in Bangladesh”.
(b)What are causes of system loss in an electricity utility and how to prevent it?
(c)Write short note on”Jamuna multipurpose Bridge Project”.
(d) i) What do you mean by”software”and “Hardware”in a computer.
3) What are its constituents?
e)What is”galaxy”?State the relative position of the sun,the earth and the moon is galaxy and their motion.
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