Wireman 2nd year mcq
Wireman – Semester 3 Module 5 – Three phase circuit
117 : What is the angular displacement of 3 phase voltages?
A : 120 electrical degrees
B : 90 electrical degrees
C : 180 electrical degrees
D : 360 electrical degrees
118 : What is the factor relating to line voltage and phase voltage?
A : √3
B : √2
C : 1
D : 3
119 : What is the formula for power in delta connection
120 : What is the value of neutral current in balanced star connected 3 phase load?
121 : What is the relation between line voltage (VL) and phase voltage (Vph) in 3 phase delta connection?
122 : What is the line voltage if phase voltage is 415V in delta connection?
A : 415V
B : 400
C : 240V
D : 138V
123 : Which is the type of load when the phase currents of a 3 phase circuit are same?
A : Balanced load
B : Unbalanced load
C : No load
D : Full load
124 : Which is the type of load if the phase currents of a 3 phase system are different?
A : Full load
B : No load
C : Balanced load
D : Unbalanced load
125 : How many number of watt meter to be used for balanced 3 phase power measurement?
A : One
B : Two
C : Three
D : Four
126 : Which method is used for 3f power measurement when load is unbalanced?
A : One watt meter method
B : Voltmeter method
C : Ammeter method
D : Three watt meter method
127 : What is the value of power factor when two watt meter readings are equal in 2 watt meter method of power measurement?
A : Unity
B : 0.5 lagging
C : 0.5 leading
D : Less than 0.5
128 : What is the reading in second watt meter W2 if the first watt meter reading is W1 = 100W at the p.f 0.5?
A : 200W
B : Zero
C : 100W
D : 50W
129 : What is the formula for total power in three watt meter method of power measurement?
A : W1 – W2
B : W1+W2+W3
C : W1+W2
D : W1(W2+W3)
130 : Where two watt meter method of power measurement is used?
A : Balanced load only
B : Unbalanced load only
C : Balanced and unbalanced load
D : Half full load
131 : What is the value of line current if phase current is 10 Amp in star connection?
A : 17.3 Amp
B : 10 Amp
C : 5 Amp
D : 9 Amp
132 : Calculate the phase current if the line current is 30 Amp in delta connection?
A : 30A
B : 17.3A
C : 15.6A
D : 10Amp
133 : Which working principle AC generator?
A : Faradays laws of electro magnetic induction
B : Ohms law
C : Lenzs law
D : Faradays laws of electrolysis
134 : Which Emf is induced in a AC generator?
A : Dynamically induced emf
B : Statically induced emf
C : Counter emf
D : Self induced emf
135 : Which part rotates in large alternator?
A : Field
B : Armature
C : Brush
D : Yoke
136 : Which material is used to construct armature core of alternator?
A : Spring steel
B : Mild steel
C : Silicon steel
D : Forged steel
137 : Which rotor is used in high speed alternator?
A : Smooth cylindrical
B : Salient pole
C : Projected pole
D : Squirrel cage rotor
138 : Which type of slots are used in armature core of alternator?
A : Totally closed
B : Wide open
C : Semi closed
D : Semi open
139 : What are the terminal markings of a 3 phase star connected alternator?
A : U, V, W and N
B : A, B, C and N
C : 1, 2, 3 and 4
D : X, Y, Z, N
140 : What is the phase displacement between three windings in an alternator?
A : 120°
B : 90°
C : 360°
D : 180°
141 : Which type of rotor has small diameter and large axial length?
A : Smooth cylindrical
B : Salient pole
C : Projecting pole
D : Squirrel cage
142 : What is the excitation source of a large alternator?
A : DC shunt generator
B : Rectifier
C : DC series generator
D : Battery
143 : Which type of alternator is used for high speed operation?
A : Salient pole alternator
B : Smooth cylindrical pure alternator
C : Projected pole alternator
D : Impulse turbo alternator
144 : How the alternators are rated?
A : KVA
B : KW
C : KVAR
D : KWH
145 : What is the Emf equation of an ideal alternator?
2 Comments
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