GATE EE

Synchronous Machines

Electrical Machines

(Past Years Questions)

Marks 1

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In a salient pole synchronous motor, the developed reluctance torque attains the maximum value when the load angle in el...
GATE EE 2018
If a synchronous motor is running at a leading power factor, its excitation induced voltage (Er) is
GATE EE 2017 Set 2
A three-phase, 50Hz, star-connected cylindrical-rotor synchronous machine is running as a motor. The machine is operated...
GATE EE 2017 Set 1
In a synchronous machine, hunting is predominantly damped by
GATE EE 2014 Set 3
A star connected 400 V, 50 Hz, 4 pole synchronous machine gave the following open circuit and short circuit test results...
GATE EE 2014 Set 1
A three-phase, salient pole synchronous motor is connected to an infinite bus. It is operated at no load a normal excita...
GATE EE 2011
In a stepper motor, the detent torque means
GATE EE 2008
Distributed winding and short chording employed in AC machines will result in
GATE EE 2008
A three phase synchronous motor connected to ac mains is running at full load and unity power factor. If its shaft load ...
GATE EE 2007
A synchronous generator is feeding a zero power factor (lagging) load at rated current the armature reaction is
GATE EE 2006
In relation to the synchronous machines, which one of the following statements is false?
GATE EE 2005
For a given stepper motor, the following torque has the highest numerical value.
GATE EE 2004
The following motor definitely has a permanent magnet rotor
GATE EE 2004
Curves X and Y in Figure denote open circuit and full-load zero power factor (zpf) characteristics of asynchronous gener...
GATE EE 2003
A stand-alone engine driven Synchronous generator is feeding a partly inductive load. A capacitor is now connected acros...
GATE EE 2003
It is desirable to eliminate 5th harmonic voltage from the phase voltage of an alternator. The coils should be short-pit...
GATE EE 2001
Figure shows the magnetization curves of an alternator at rated armature current, unity power factor and also at no load...
GATE EE 2001
Xd, Xd' and Xd" are steady stated-axis synchronous reactance, transient d-axis reactance and sub-transient d-axis reacta...
GATE EE 2001
The phase sequence of a three-phase alternator will reverse if
GATE EE 2000
Higher synchronous reactance is preferred in the present day alternators, because one can have
GATE EE 1999
A synchronous generator connected to an infinite bus is overexcited. Considering only the reactive power, from the point...
GATE EE 1998
During hunting of synchronous motor
GATE EE 1996
In Figure. The characteristic that corresponds to the variation of synchronous reactance of synchronous motor with field...
GATE EE 1996
A synchronous motor on load draws a current at a leading power factor angle $$\phi$$. If the internal power factor angle...
GATE EE 1995
The torque angle of a synchronous machine operating from a constant voltage bus, is usually defined as the space angle b...
GATE EE 1992
The developed electromagnetic force and or torque in electro $$-$mechanical energy conversion systems act in a directi...
GATE EE 1992

Marks 2

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A $$3$$-phase, $$2$$-pole, $$50$$ $$Hz,$$ synchronous generator has a rating of $$250$$ $$MVA,$$ $$0.8$$ $$pf$$ lagging....
GATE EE 2017 Set 2
Two generating units rated $$300$$ $$MW$$ and $$400$$ $$MW$$ have governor speed regulation of $$6\% $$ and $$4\% $$ res...
GATE EE 2017 Set 2
A $$25$$ $$kVA,$$ $$400$$ $$V,$$ $$\Delta $$ - connected, $$3$$-phase, cylindrical rotor synchronous generator requires ...
GATE EE 2017 Set 2
Two parallel connected, three-phase, $$50Hz,$$ $$11kV,$$ star-connected synchronous machines $$A$$ and $$B,$$ are operat...
GATE EE 2017 Set 1
A three-phase, $$50$$ $$Hz$$ salient-pole synchronous motor has a per-phase direct-axis reactance $$\left( {{X_d}} \righ...
GATE EE 2016 Set 1
A three-phase, $$11$$ $$kV,$$ $$50$$ $$Hz,$$ $$2$$ pole, star connected, cylindrical rotor synchronous motor is connecte...
GATE EE 2015 Set 2
A non-salient pole synchronous generator having synchronous reactance of $$0.8$$ $$pu$$ is supplying $$1$$ $$pu$$ power ...
GATE EE 2014 Set 3
A $$20$$-pole alternator is having $$180$$ identical stator slots with $$6$$ conductors in each slot. All the coils of a...
GATE EE 2014 Set 2
A synchronous generator is connected to an infinite bus with excitation voltage $${E_f} = 1.3\,pu.$$ The generator has a...
GATE EE 2014 Set 2
There are two generators in a power system. No-load frequencies of the generators are $$51.5$$ $$Hz$$ and $$51$$ $$Hz,$$...
GATE EE 2014 Set 2
A three phase synchronous generator is to be connected to the infinite bus. The lamps are connected as shown in the figu...
GATE EE 2014 Set 1
The direct axis and quadrature axis reactances of a salient pole alternator are $$1.2$$ $$p.u$$ and $$1.0$$ $$p.u$$ resp...
GATE EE 2011
A $$50$$ $$Hz$$ synchronous generator is initially connected to a long lossless transmission line which is open circuite...
GATE EE 2010
A separately excited $$dc$$ machine is coupled to a $$50Hz,$$ three-phase, 4-pole induction machine as shown in the figu...
GATE EE 2010
A field excitation of $$20A$$ in a certain alternator results in a armature current of $$400$$ $$A$$ in short circuit an...
GATE EE 2009
A synchronous motor is connected to an infinite bus at $$1.0$$ $$p.u$$ voltage and draws $$0.6$$ $$pu$$ at unity power ...
GATE EE 2008
A synchronous motor is connected to an infinite bus at $$1.0p.u$$ voltage and draws $$0.6$$ $$pu$$ at unity power facto...
GATE EE 2008
A $$3$$ phase, $$3$$ stack, variable reluctance stepper motor has $$20$$ poles on each rotor and stator stack. The step ...
GATE EE 2007
A $$100$$ $$kVA$$, $$415V,$$ star connected synchronous machine generates rated open circuit voltage $$415V$$ at a fiel...
GATE EE 2007
A $$3$$-phase $$4000$$ $$V,$$ $$5$$ $$kW,$$ star connected synchronous motor having an internal reactance of $$10$$ $$oh...
GATE EE 2006
A $$4$$ pole, $$50$$ $$Hz,$$ synchronous generator has $$48$$ slots in which a double layer winding is house. Each coil...
GATE EE 2006
A $$4$$ pole, $$50$$ $$Hz,$$ synchronous generator has $$48$$ slots in which a double layer winding is house. Each coil...
GATE EE 2006
A $$1000$$ $$kVA,$$ $$6.6$$ $$kV,$$ $$3$$-phase star connected cylindrical pole synchronous generator has a synchronous ...
GATE EE 2005
A $$1000$$ $$kVA,$$ $$6.6$$ $$kV,$$ $$3$$-phase star connected cylindrical pole synchronous generator has a synchronous ...
GATE EE 2005
The synchronous speed for the seventh space harmonic $$mmf$$ wave of a $$3$$-phase, $$8$$ pole, $$50$$ $$Hz$$ induction ...
GATE EE 2004
Two $$3$$-phase, $$Y$$-connected alternators are to be paralleled to a set of common bus bars. The armature has a per ph...
GATE EE 2004
For a $$1.8$$ degree, $$2$$-phase bipolar stepper motor, the stepping rate is $$100$$ steps/second. The rotational speed...
GATE EE 2004
A $$400$$ $$V,$$ $$50$$ $$kVA,$$ $$0.8$$ $$pf$$ leading delta connected, $$50$$ $$Hz$$ synchronous machine has a synchro...
GATE EE 2004
A $$500$$ $$MW$$ $$3$$-phase $$Y$$-connected synchronous generator has a rated voltage of $$21.5kV$$ at $$0.85$$ $$pf.$$...
GATE EE 2004
A hydraulic turbine having rated speed of $$250$$ $$rpm$$ is connected to a synchronous generator. In order to produce p...
GATE EE 2004
A $$4$$-pole, $$3$$-phase, double layer winding is housed in a $$36$$-slot stator for an $$ac$$ machine with $$60$$ degr...
GATE EE 2003
The flux per pole in a synchronous motor with the field circuit ON and the stator disconnected from the supply is found ...
GATE EE 2002
A star-connected 440 V, 50 Hz alternators has per phase synchronous reactance of 10 Ω. It supplies a balanced capacitive...
GATE EE 2001
A single-phase, 2000 V alternator has armature resistance and reactance of 0.8 ohms and 4.94 ohms respectively. The volt...
GATE EE 2000
A three phase alternator is wound with a 60 degree phase-spread armature windings and develops 300 kVA. If the armature ...
GATE EE 1999
The armature of a single phase alternator is completely wound with T single turn coils distributed uniformly. The induce...
GATE EE 1998
A single-phase alternator has a synchronous reactance of $$2$$ $$ohms$$ and negligible resistance. If it supplies $$10$$...
GATE EE 1997
A three phase alternator has negligible stator resistance. A short circuit test is conducted on this alternator. At a pa...
GATE EE 1993
A synchronous motor operates at $$0.8$$ $$p.f.$$ lagging. If the field current of the motor is continuously increased $...
GATE EE 1993
Two $$550$$ $$kVA$$ alternators operate in parallel to supply the following loads $$(i)$$ $$250$$ $$kW$$ at $$0.95$$ po...
GATE EE 1993

Marks 5

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A $$415$$ $$V,$$ $$2$$ pole, $$3$$ phase, $$50$$ $$Hz,$$ star connected, non-salient pole synchronous motor has synchron...
GATE EE 2002
A $$50$$ $$kW$$ synchronous motor is tested by driving it by another motor. When the excitation is not switched on, the ...
GATE EE 2001
Two identical synchronous generators, each of $$100$$ $$MVA,$$ are working in parallel supplying $$100$$ $$MVA$$ at $$0....
GATE EE 2001
A $$2300$$ $$V,$$ $$3$$-phase synchronous motor driving a pump is provided with a line ammeter and a field rheostat. Whe...
GATE EE 2000
A $$5MVA$$, $$11kV$$, $$3$$-phase star connected alternator is synchronized to the bus bars and is operating with an ind...
GATE EE 1997
The per unit voltage of two synchronous machines connected through a lossless line are $$0.95\,\,\angle \,{10^0}\,\,$$ a...
GATE EE 1996
The distribution factor for a $$36$$ slot stator with three-phase, $$8$$-pole winding, having $${120^ \circ }$$ phase Sp...
GATE EE 1995
Figure depicts the load characteristics of an constant speed. Match the following sets of operating conditions with the ...
GATE EE 1992

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