Last Answer : Short circuit test on transformers is conducted to determine copper losses.
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
Last Answer : Slip test is performed to determine : Xd and Xq in a salient pole alternator
Even at no-load, a transformer draws current from the mains. Why?
Sumpner's test is conducted on transformer to determine?
Last Answer : Sumpner's test is conducted on transformer to determine temprature.
During open circuit test of a transformer?
Last Answer : During open circuit test of a transformer primary is supplied rated voltage.
An open-circuit test on a transformer is conducted primarily to measure?
Last Answer : The open-circuit test in a transformer is used to measure
Last Answer : High Voltage side is open circuited.
Last Answer : Primary side is low voltage side and secondary side is high voltage side.
Polarity Test of Transformer
Last Answer : Polarity Test of Transformer
Explain the procedure to perform Short Circuit test on single phase transformer with circuit diagram.
Explain the open delta (delta-delta) test on transformer.
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
Last 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.
Last Answer : Low voltage side is short circuited.
Last Answer : Primary is high voltage side and Secondary is low Voltage side.
Last Answer : In short circuit test of transformer the low voltage side is short circuited . On high voltage side the voltmeter is connected in parallel and ammeter in series and also a wattmeter is ... circuit test is done for determining impedance and losses. In this test iron losses is neglected.
A parallel RLC circuit has the node equation Determine v(t) using the phasor method.
Last Answer : A parallel RLC circuit has the node equation Determine v(t) using the phasor method.
Using phasors, determine in the following equations
Last Answer : Using phasors, determine in the following equations
In a battery, the difference between the no-load voltage and the measured voltage output is called ________ A) Internal voltage B) Internal resistance C) External resistance D) All the above
Last Answer : In a battery, the difference between the no-load voltage and the measured voltage output is called Internal resistance
The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α
Last Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ
Last Answer : Series motor should not be started on no-load.
Why phasing out and polarity test is carried out on three phase transformer?
Last 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.
Last Answer : No-load current in a transformer lags behind the voltage by about 75°.
Last Answer : The no load current in a transformer lags behind the applied voltage by an angle of about 75°.
Last Answer : No-load current of a transformer has small magnitude and low power factor.
In an actual transformer the iron loss remains practically constant from no load to full load because?
Last Answer : In an actual transformer the iron loss remains practically constant from no load to full load because core flux remains practically constant.
Last Answer : The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be 400 W.
Last Answer : An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?
Last Answer : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.
For a transformer, operating at constant load current, maximum efficiency will occur at?
Last Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.
The maximum load that a power transformer can carry is limited by its?
Last Answer : The maximum load that a power transformer can carry is limited by its voltage ratio.
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of?
Last Answer : In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of less than 15A.
Last Answer : Noise level test in a transformer is a type test.
Why SC test is generally performed on HV side of a transformer?
Last Answer : The rated current is less on HV side. This will also permit to use ammeter and wattmeter of lower current range.
Why OC test is generally performed on LV side of a transformer?
Last Answer : The high-voltage side is generally kept open because the current in high-voltage winding is less compared to that on low-voltage winding.The LV side has higher current so that maximum no load current can be measured.
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.
Last 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
Explain the effect of Harmonics on the Transformer.
Last Answer : Effect of Harmonics on the Transformer: 1. Core loss: Harmonic voltage increases the hysteresis and eddy current losses in the lamination. The amount of the core loss depends on ... small core vibrations. 5. Saturation problem: Sometimes additional harmonic voltage causes core saturation.
List two special feature of welding transformer.
Last Answer : Special features of welding transformer: i) It is a step down transformer that reduces the source voltage to a voltage desired according to the demands of the welding process. ii) Having large primary turns and less ... V ii) Secondary voltage - 40 to 60 V iii) Secondary current - 200 to 600 A
State two applications of isolation transformer
Last Answer : Applications of isolation transformer: i) Isolates the load equipment from supply ground: ii) Reduction of voltage spikes iii) It acts as a decoupling device. iv) Protects loads from harmonic distortion.
State why a transformer always have an efficiency of more than 90%.
Last Answer : As transformer is static device with no moving parts, the losses due to friction & windage are completely absent. Hence transformer has efficiency of more than 90%.
Equivalent circuit of transformer
Last Answer : Equivalent Circuit Diagram of Transformer Referred to Primary: V1 -Primary Input voltage I1 - Input Current I0- Exciting current/ No load current Im- Magnetizing component ... equivalent of secondary terminal voltage ZL- Load impedance ZL ′- Primary equivalent of load impedance
Single phase transformer
Last Answer : Single phase Transformer Transformer
What is the use of transformer?
Last Answer : The use of transformer is to do lower or raise the voltage or currents in an electrical circuit. That's quite so simple.
Write about transformer on DC.
Last Answer : Transformer on DC : Transformer cannot work on DC. Transformer works on electromagnetic induction principle. Electromagnetic induction principle means when flux linking with coil changes and EMF induced in it ... winding insulation will burn. https://youtu.be/TVp_0fIfxqY
State and justify which of the following two transformers is better: Transformer A = 4% voltage regulation Transformer B = 6% voltage regulation
Last Answer : Transformer A with 4% voltage regulation is better. Justification: Voltage regulation refers to the percentage change in secondary voltage when load is changed from no-load to full-load with primary voltage ... 4% voltage regulation, which is less as compared to 6% of transformer B, it is better.
State any four characteristics of core type transformer.
Last Answer : Characteristics of core type transformer: i) It has one window. ii) It has one magnetic circuit. iii) Core surrounds the winding. iv) Average length of core is more. v) Area of cross ... Better cooling for winding. vii) Mechnical strength is comparatively less. viii) Repair and maintenance is easy.
Explain construction and working of single phase Auto transformer.
Last Answer : Construction of single phase auto transformer: (i) It has only one winding wound on a laminated circular magnetic core. (ii) The core is made of silicon steel stampings. (iii) The two terminals of the ... help of handle. 5) The same transformer can be used as step-up or step down auto-transformer
Last Answer : The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.
Last Answer : In the transformer low voltage winding has got more cross-sectional area.
Last Answer : A transformer cannot raise or lower the voltage of a D.C. supply because Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero.
Last Answer : Primary winding of a transformer could either be a low voltage or high voltage winding.