Engineering :: Energy Conversion

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271.

The main advantage of ac transmission system over dc transmission system is

A.	easy transmission	B.	less insulation problems
C.	less problems of instability	D.	less losses in transmission over long distances

272.

Material generally used for bus bars is

A.	cast iron	B.	tungsten
C.	Stainless steel	D.	copper

273.

In a transmission line if booster transformer is to be used, the preferred location will be

A.	at the receiving end	B.	at the sending end
C.	at the intermediate point	D.	anywhere in the line

274.

In case the height of transmission towers is increased

A.	the line capacitance and inductance will not change	B.	the line capacitance will increase but line inductance will increase
C.	the line capacitance will decrease and line inductance will increase	D.	the line capacitance will decrease but line inductance will remain unaltered

275.

In ACSR conductors

A.	varnish is the insulation used	B.	bitumen is the insulation between aluminium and steel
C.	no insulation is used between aluminium and steel	D.	air acts as insulation medium between aluminium and steel

276.

Under no load conditions the current in a transmission line is due to

A.	corona effects	B.	capacitance of the line
C.	back flow from earth	D.	spinning reserve

277.

Stability of a system is least affected by

A.	reactance of line	B.	losses
C.	reactance of generator	D.	output forque

278.

Which of the following equipment is not installed in a substation?

A.	Exciters	B.	Series capacitors
C.	Shunt reactors	D.	Voltage transformers

279.

ACSR conductor having 7 steel strands surrounded by 25 aluminium conductors will be specified as

A.	7?25	B.	7?32
C.	25?7	D.	25?32

280.

Which of the following short-circuit is the most dangerous?

A.	Line to line short circuit	B.	Dead short circuit
C.	Line to ground short circuit	D.	Line to line and ground short circuit