Answer :
Short circuit test on transformers is conducted to determine copper losses.
asked
Mar 19, 2018
by
anonymous
Description : An open-circuit test on a transformer is conducted primarily to measure?
Answer :
The open-circuit test in a transformer is used to measure
asked
Mar 19, 2018
by
anonymous
Description : Sumpner's test is conducted on transformer to determine?
Answer :
Sumpner's test is conducted on transformer to determine temprature.
asked
Mar 19, 2018
by
anonymous
Answer :
The purpose of retardation test on D.C. shunt machines is to find out stray losses.
asked
Mar 20, 2018
by
anonymous
Answer :
Satisfactory commutation of D.C. machines requires brushes should be of proper grade and size, brushes should smoothly run in the holders, smooth, concentric commutator properly undercut.
asked
Mar 20, 2018
by
anonymous
Answer :
Brushes of D.C. machines are made of carbon.
asked
Mar 20, 2018
by
anonymous
Answer :
In D.C. machines the residual magnetism is of the order of 2 to 3 percent.
asked
Mar 20, 2018
by
anonymous
Answer :
In D.C. machines fractional pitch winding is used to reduce the sparking.
asked
Mar 20, 2018
by
anonymous
Description : In dc machines, the armature windings are placed on the rotor because of the necessity for (1) electromechanical energy conversion (2) generation of voltage (3) commutation (4) development of torque
Answer :
3 Commutation
asked
May 1, 2018
by
anonymous
Description : Brake test on DC series motor
Answer :
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asked
Apr 21, 2020
by
anonymous
Description : DC motor brake test numerical
Answer :
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asked
Apr 22, 2020
by
anonymous
Description : A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.
Answer :
Iron loss is dependent on voltage and independent of load. Hence iron loss at 75% of Load = Iron loss at full load = 2 kW
Description : Draw the connection diagram of long shunt differential D.C. compound generator.
Answer :
Ans:
Description : Compare core type transformer and shell type transformer on the following parameters. (i) Types of winding used, (ii) Application
Answer :
Ans:
Description : State any two applications of single phase autotransformer.
Answer :
Applications of single phase auto transformers: 1) Give small boost to distribution cable to correct the voltage drop. 2) As auto transformer starter for induction motors. 3) As furnace supply ... . 5) In control equipment for single phase locomotives. 6) As dimmer in lighting circuits.
Description : State any two conditions for parallel operation of 3-phase transformer.
Answer :
Conditions for Parallel operation of 3 phase transformer 1) Voltage ratings of both the transformers must be identical. 2) Percentage or p.u. impedance should be equal in magnitude. 3) X/R ratio ... between primary & secondary voltages must be same. 6) Phase sequence on both sides must be same.
Description : Define transformation ratio in terms of current and voltage.
Answer :
(i) Transformation Ratio (K) is defined as the ratio of the primary current to the secondary current. (ii) Transformation Ratio (K) is defined as the ratio of the secondary voltage to the primary voltage.
Description : Define: (i) Commercial efficiency of a transformer and (ii) All day efficiency of a transformer.
Answer :
(i) Commercial Efficiency : It is the ratio of output power in watt to the input power in watt. (ii) All day efficiency of a transformer: It is the ratio of output energy in kWh to the input energy in kWh in the 24 hours of the day
Description : State any four properties of Ideal transformer.
Answer :
Properties of Ideal transformer: 1) No losses (iron and copper losses), hence no temperature rise. 2) No magnetic leakage i.e (Coefficient of coupling between primary and secondary windings is unity) 3) Zero winding ... drop i.e. E1 = V1, E2 = V2 5) Efficiency 100 %. 6) Regulation 0 %.
Answer :
For a D.C. machines laboratory following type of D.C. supply will be suitable induction motor D.C. generator set.
asked
Mar 20, 2018
by
anonymous
Description : Explain the procedure to perform Short Circuit test on single phase transformer with circuit diagram.
asked
Apr 27, 2020
by
anonymous
Description : With the help of neat diagram, describe the procedure to carry out phasing out test on a 3 phase transformer. Also state the purpose of conducting this test on 3 phase transformer.
Answer :
i) This test is carried out on 3-ph transformer to identify primary & secondary winding belonging to the same phase. ii) As shown in fig above all primary & secondary phases ... of this test is to check the respective phases of primary & secondary windings in 3-ph transformer
asked
Apr 27, 2020
by
anonymous
Description : Explain the open delta (delta-delta) test on transformer.
asked
Apr 27, 2020
by
anonymous
Description : Explain the need and steps to conduct the reduced voltage running up test on the three phase induction motor.
asked
Apr 16, 2020
by
anonymous
Description : Why phasing out and polarity test is carried out on three phase transformer?
Answer :
The phasing out test is carried out to identify the windings (primary and secondary) of corresponding phase of the three phase transformer. The polarity test is carried out to identify the ... identical polarity of the primary and secondary windings of each phase of the three phase transformer.
asked
Jul 27, 2019
by
anonymous
Answer :
The duration of sudden short-circuit test on a synchronous motor is usually about one second.
asked
Mar 20, 2018
by
anonymous
Description : A no-load test is performed on a transformer to determine?
Answer :
A no-load test is performed on a transformer to determine magnetizing current and loss.
asked
Mar 19, 2018
by
anonymous
Description : Write measures to be taken to maintain the insulation resistance of electrical machines to healthy levels.
asked
Apr 16, 2020
by
anonymous
Description : What type of motor is used for drilling machines?
Answer :
universal motor also used in Handheld power tools, blowers, blenders, vacuum cleaners, polishers and kitchen appliances.universal motor is defined as a motor which may be operated either on direct or single phase AC supply at approximately the same speed and output
asked
Aug 18, 2019
by
anonymous
Description : The inertia constants of two groups of machines which do not swing together are M1 and M2. The equivalent inertia constant of the system is
Answer :
The inertia constants of two groups of machines which do not swing together are M1 and M2. The equivalent inertia constant of the system is M1M2/M1+M2
asked
May 3, 2018
by
anonymous
Description : For protection of rotating machines against lightning surges _______ is used. (1) lightning arrester (2) capacitor (3) combination of lightning arrester and capacitor (4) lightning conductor and arrester
Answer :
For protection of rotating machines against lightning surges combination of lightning arrester and capacitor is used.
asked
Apr 30, 2018
by
anonymous
Description : Laminated cores, in electrical machines, are used to reduce?
Answer :
Laminated cores, in electrical machines, are used to reduce eddy current loss.
asked
Mar 25, 2018
by
anonymous
Description : Silicon steel is used in electrical machines because it has?
Answer :
Silicon steel is used in electrical machines because it has low hysteresis loss.
asked
Mar 25, 2018
by
anonymous
Answer :
The speed control of universal motor used for sewing machines is by varying the resistance.
asked
Mar 20, 2018
by
anonymous
Answer :
Exciters of synchronous machines are d.c. shunt machines.
asked
Mar 20, 2018
by
anonymous
Description : Losses which occur in rotating electric machines and do not occur in transformers are?
Answer :
Friction losses windage losses
asked
Mar 19, 2018
by
anonymous
Description : Polarity Test of Transformer
Answer :
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asked
Apr 30, 2020
by
anonymous
Description : What is test bench? Write its applications
Answer :
Test Bench: A test bench is used to verify the functionality of the design. We need to stimulate our designs in order to test their functionality. Stimulus in a real system is from an ... the entity under test and to collect output responses. 6. To compare output responses with expected values.
asked
Jul 22, 2019
by
anonymous
Description : Slip test is performed to determine : (A) Slip in an induction motor (B) Xd and Xq in a salient pole alternator (C) Synchronous impedance in an alternator (D) Positive and negative sequence impedances of an alternator
Answer :
Slip test is performed to determine : Xd and Xq in a salient pole alternator
asked
Apr 29, 2018
by
anonymous
Description : If a 5-bus test system contains 6 transmission lines and one transformer, how many non-zero elements are there in the system Y-bus ? (A) 25 (B) 12 (C) 11 (D) 19
Answer :
If a 5-bus test system contains 6 transmission lines and one transformer, 19 non-zero elements are there in the system Y-bus.
asked
Apr 28, 2018
by
anonymous
Answer :
Murray loop test can be used for location of both the ground fault and the short-circuit fault.
asked
Mar 21, 2018
by
anonymous
Description : During open circuit test of a transformer?
Answer :
During open circuit test of a transformer primary is supplied rated voltage.
asked
Mar 19, 2018
by
anonymous
Description : How do you test a capacitor with a multimeter?
asked
Mar 15, 2018
by
anonymous
Description : How do we test a diode?
asked
Mar 15, 2018
by
anonymous
Description : How do you test a triac?
asked
Mar 15, 2018
by
anonymous
Description : How do you test an SCR?
asked
Mar 15, 2018
by
anonymous
Description : Why high voltage test is done?
asked
Mar 10, 2018
by
anonymous
Description : What is an insulation resistance test?
asked
Mar 10, 2018
by
anonymous
Description : What is a high voltage test?
asked
Mar 10, 2018
by
anonymous
Answer :
Low voltage side is short circuited.
asked
Sep 27, 2017
by
anonymous