1
GATE EE 1997
Fill in the Blanks
+5
-0
A $$5$$ $$kW,$$ $$200V$$ $$d.c.$$ shunt motor has an armature resistance of $$1$$ $$ohm$$ and shunt field resistance of $$100$$ $$ohms.$$ At no-load, the motor draws $$6A$$ from a $$200$$ $$V$$ supply and runs at $$1000$$ $$rpm.$$ The rotational loss of the machine is ______________ $$W$$ and the no load torque is ____________ $$N$$-$$m$$
2
GATE EE 1997
MCQ (Single Correct Answer)
+2
-0.6
A voltage $$V=400$$ sin $$314.16t$$ is applied to a $$1$$-phase transformer on no-load. If the no load current of the transformer is $$2\sin \left( {314.16t - {{85}^0}} \right),\,\,$$ then magnetization branch impedance will be approximately
A
$$141\,\,\angle 90$$
B
$$200\,\,\angle - 85$$
C
$$200\,\,\angle 85$$
D
$$282\,\,\angle - 80$$
3
GATE EE 1997
Numerical
+2
-0
A $$3$$-phase transformer bank consists of three identical $$2300/230$$ $$V,$$ $$15$$ $$kVA$$ single-phase transformers connected in delta/delta. The bank supplies a $$20$$ $$kVA,$$ unity $$p.f.$$ $$3$$-phase load. If one of the single-phase transformer develops a fault, and is removed, the load carried by each of the two transformers now operating in open delta will be __________$$kVA.$$
Your input ____
4
GATE EE 1997
Subjective
+5
-0
At $$50\% $$ of full load, the armature current drawn by a $$d.c.$$ shunt motor is $$40$$ A when connected to a $$200$$ $$V$$ $$d.c.$$ mains. By decreasing the field flux, its speed is raised by $$20\% $$ this also causes a $$10\% $$ increase in load torque. Calculate the percentage change in field current. The armature resistance including the brushes is $$1$$ $$Ohm.$$ Neglect saturation and armature reaction.