The rating of transformer may be expressed in ____________. (A) kVAR (B) kW (C) kVA (D) Horse power
Last Answer : The rating of transformer may be expressed in kVA .
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1 answer
asked
May 8, 2018
by
anonymous

Why Transformer rating is given in kVA?
Last Answer : Because of core losses and iron losses as core losses are measured in amps and cu losses in voltage ....this is definatly reason for the rating Or kVA is the unit for apparent power. Apparent ... shift between voltage and current). So a transformer has to be rated (and selected) by apparent power.
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2.8k views
6 answers
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Aug 12, 2018
by
anonymous

Define kVA rating of transformer.
Last Answer : kVA rating of transformer is defined as the product of voltage (V) and current (I) on primary side of transformer or secondary side of transformer divided by 1000. On both side the VA rating remains ... Mathematically kVA rating is given by, kVA rating of transformer = V1I1/1000 =V2I2/1000
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158 views
1 answer
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Aug 12, 2018
by
anonymous

The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : (A) 34.64 kVA (B) 75 kVA (C) 20 kVA (D) None of the above
Last Answer : The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : 34.64 kVA
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199 views
1 answer
asked
May 8, 2018
by
anonymous

The transformer ratings are usually expressed in terms of A. Volts B. Amperes C. kW D. kVA
Last Answer : D) KVA
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113 views
1 answer
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Last Answer : The fuse rating is expressed in terms of current.
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151 views
1 answer
asked
Mar 20, 2018
by
anonymous

Boiler rating is usually defined in terms of (1) Maximum temperature of steam in Kelvin (2) Heat transfer rate in KJ/hr (3) Heat transfer area in metre2 (4) Steam output in kg/hr
Last Answer : Boiler rating is usually defined in terms of Steam output in kg/hr
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212 views
1 answer
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Apr 29, 2018
by
anonymous

Last Answer : Material used for construction of transformer core is usually silicon steel.
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241 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : The thickness of laminations used in a transformer is usually 0.4 mm to 0.5 mm.
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98 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds 150°C.
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195 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The magnetising current of a transformer is usually small because it has small air gap.
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78 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The core used in high frequency transformer is usually air core .
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213 views
1 answer
asked
Mar 19, 2018
by
anonymous

Where would you rate Ronald Reagan among US Presidents?
Last Answer : I think the “fat little dutchman” did good, made me laugh on numerous occasions.
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1 answer
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Feb 27
by
anonymous

On a scale from 0 to 10, how do you rate the numbers in that scale?
Last Answer : 1: 1 2: 2 3: 3 4: 4 5: 7 6: 5 7: 6 8: 10 9: 8 10: 9
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1 answer
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Feb 27
by
anonymous

How rating of main switch and cable is selected for Industrial Installation.
Last Answer : 1. Rating of Main Switch or Fuse Rating is decided in industrial installation: Rating of main switch or fuse is based up the starting current of motor. For calculating starting current is considered 2 ... take 1.5 times the rated current or full load current. & thus cable rating is decided.
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325 views
1 answer
asked
Sep 20, 2018
by
anonymous
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Last Answer : For the same H.P. rating and full load speed, following motor has poor starting torque differentially compounded.
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164 views
1 answer
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Mar 20, 2018
by
anonymous
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Last Answer : The wattage rating for a ceiling fan motor will be in the range 50 to 150 W .
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177 views
1 answer
asked
Mar 20, 2018
by
anonymous

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.
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127 views
1 answer
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May 22, 2020
by
anonymous

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
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146 views
1 answer
asked
May 22, 2020
by
anonymous

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.
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54 views
1 answer
asked
May 22, 2020
by
anonymous
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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%.
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262 views
1 answer
asked
May 22, 2020
by
anonymous

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
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381 views
2 answers
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May 17, 2020
by
anonymous

Single phase transformer
Last Answer : Single phase Transformer Transformer
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260 views
1 answer
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May 16, 2020
by
anonymous

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.
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159 views
1 answer
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May 15, 2020
by
anonymous

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
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248 views
1 answer
asked
May 10, 2020
by
anonymous
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Even at no-load, a transformer draws current from the mains. Why?
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114 views
0 answers
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Apr 28, 2020
by
anonymous

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.
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178 views
1 answer
asked
Jul 27, 2019
by
anonymous

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.
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132 views
1 answer
asked
Jul 27, 2019
by
anonymous

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
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344 views
1 answer
asked
Jul 26, 2019
by
anonymous

Last Answer : No-load current in a transformer lags behind the voltage by about 75°.
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90 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.
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202 views
1 answer
asked
Mar 19, 2018
by
anonymous
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Last Answer : In the transformer low voltage winding has got more cross-sectional area.
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256 views
1 answer
asked
Mar 19, 2018
by
anonymous

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.
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344 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : Primary winding of a transformer could either be a low voltage or high voltage winding.
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1 answer
asked
Mar 19, 2018
by
anonymous
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Last Answer : High voltage winding in a transformer has more number of turns.
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361 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The efficiency of a power transformer is of the order of 98 percent.
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99 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The no load current in a transformer lags behind the applied voltage by an angle of about 75°.
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188 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : In a transformer, routine efficiency depends upon load current and power factor of load.
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133 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : The maximum efficiency of a distribution transformer is at 50% full load.
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139 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : Transformer breaths in when load on it decreases.
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90 views
1 answer
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Mar 19, 2018
by
anonymous
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Last Answer : No-load current of a transformer has small magnitude and low power factor.
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72 views
1 answer
asked
Mar 19, 2018
by
anonymous
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Last Answer : The purpose of providing iron core in a step-up transformer is to decrease the magnitude of magnetizing current.
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545 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The power transformer is a constant main flux device.
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63 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : In a transformer, the tappings are generally provided on low voltage side.
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92 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The use of higher flux density in the transformer design reduces weight per kVA.
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126 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The chemical used in breather for transformer should have the quality of cleansing the transformer oil.
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187 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : An ideal transformer has infinite values of primary and secondary inductances. The statement is false.
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324 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : conservator or a reservoir tank for insulating oil in transformer which used for balanced the onload oil level with help of oil level indicator which mount on middle part of reservoir tank.
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177 views
3 answers
asked
Mar 19, 2018
by
anonymous

Last Answer : A transformer oil must be free from moisture.
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68 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The main reason for generation of harmonics in a transformer could be saturation of core.
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128 views
1 answer
asked
Mar 19, 2018
by
anonymous
