Description : 30 In performing the short circuit test of a transformer A. high voltage is usually short circuited B. low voltage side is usually short circuited C. any side is short circuited with preference D. none of the above
Last Answer : B. Low voltage side is usually short circuited
Description : During short circuit test iron losses are negligible because A. The current on secondary side is negligible B. The voltage on secondary side does not vary C. The voltage applied on primary side is low D. Full-load current is not supplied to the transformer
Last Answer : C) the voltage applied on primary side is low
Last Answer : Low voltage side is short circuited.
Last Answer : Primary is high voltage side and Secondary is low Voltage side.
Last Answer : High Voltage side is open circuited.
Description : The secondary of a current transformer is always short-circuited under operating conditions because it?
Last Answer : The secondary of a current transformer is always short-circuited under operating conditions because it avoids core saturation and high voltage induction.
Last Answer : Primary side is low voltage side and secondary side is high voltage side.
Description : When secondary of a current transformer is open-circuited its iron core will be?
Last Answer : When secondary of a current transformer is open-circuited its iron core will be hot because of heavy iron losses taking place in it due to high flux density.
Description : If we give 2334 A, 540V on Primary side of 1.125 MVA step up transformer, then what will be the Secondary Current, If Secondary Voltage=11 KV?
Last Answer : A. As we know the Voltage & current relation for transformer-V1/V2 = I2/I1 We Know, VI= 540 V; V2=11KV or 11000 V; I1= 2334 Amps. By putting these value on Relation540/11000= I2/2334 So,I2 = 114.5 Amps
Description : 52 A transformer has 1000 primary turns, connected to 250V ac supply. To get 400V secondary voltage the no of secondary turns should be A. 1600 B. 250 C. 400 D. 1250
Last Answer : A. 1600
Description : 29.In transformer terminology, the ratio 20:1 indicates that A. there are 20 turns on primary one turn on secondary B. secondary voltage is 1/20th of the primary C. primary current is 20 times greater than the secondary current D. for every 0 turns on primary, there is one turn on secondary
Last Answer : A. there are 20 turns on primary one turn on secondary
Description : The frequency of the secondary voltage of a transformer will be..... A. less than frequency of the primary voltage B. equal to the primary voltage C. greater than the frequency of the primary voltage D. much greater than the frequency of the primary voltage
Last Answer : B. Equal to the primary voltage
Description : In a Tap changing transformer on which side is the tap connected, primary side or secondary side?
Last Answer : A. Tapings are always connected to high voltage winding side, because of low current. If we connect tapings to low voltage side, sparks will produce while tap changing operation due to high current.
Description : 64)During the short-circuit test on a small transformer the frequency is increased from 50-200Hz. The copper losses will increase by a factor of A. 16 B. 4 C. 1 D. 1/4
Last Answer : A) 16
Description : [53] The iron loss of the transformer is negligible during short circuit test because A. The entire input is just sufficient to meet Cu losses only B. Flux produced is a small fraction of the normal flux C. Iron core becomes fully saturated D. Supply frequency is held constant
Last Answer : B. Flux produced is a small fraction of the normal flux
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.
Description : Why the open circuit test on a transformer is conducted at rated voltage?
Last Answer : A:The open circuit on a transformer is conducted at a rated voltage because core loss depends upon the voltage. This open circuit test gives only core loss or iron loss of the transformer.
Description : What current flows in the transformer primary when its secondary is open?
Last Answer : A. When the secondary is open, there is no current in the secondary of the transformer. The primary takes a small current I0) from the source called no-load current which has a magnetizing ... ) producing the magnetic flux and a working component (I0 cosθ0) supplying real power for iron losses.
Description : 59.An ideal transformer has infinite values of primary and secondary inductances. The statement is A. True B. False
Last Answer : B. False
Description : 57 In a transformer the resistance between its primary and secondary is A. Zero B. 1Ω C. 1000 Ω D. Infinite
Last Answer : D. Infinite
Description : 50 The equivalent resistance of the primary of the transformer having K = 5, R1 = 0.1 ohm when referred to secondary becomes .....ohm A. 0.5 B. 0.02 C. 0.004 D. 2.5
Last Answer : A. 0.5
Description : 38] In a transformer the energy is conveyed from primary to secondary? A. Through cooling coil B. Through air C. By the flux D. None of the above
Last Answer : C. By the flux
Description : 28.In a two winding transformer, the emf /turn in secondary winding is always......the induced emf power turn in primary A. equal to k times B. equal to 1/k times C. equal D. greater than
Last Answer : C. equal
Description : 6 In a two winding transformer, the primary and secondary induced emf E1 & E2 are always A. equal in magnitude B. anti phase with each other C. in phase with each other D. determined by load on transformer secondary
Last Answer : C. In phase with each other
Description : 12] Which is not the basic element of the transformer? A. core B. primary winding C. secondary winding D. mutual flux
Last Answer : D. Mutual flux
Description : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary? (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts
Last Answer : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary? (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts
Last Answer : An ideal transformer has infinite values of primary and secondary inductances. The statement is false.
Description : In a transformer the resistance between its primary and secondary should be?
Last Answer : In a transformer the resistance between its primary and secondary should be infinity.
Description : 48.During light loads, the transformer efficiency is low because A. Secondary output is low B. Transformer losses are high C. Fixed loss is high in proportion to the output D. Cu loss is small
Last Answer : C. Fixed loss is high in proportion to the output
Last Answer : yes High Voltage side of Transformer winding have more number of turns. and low voltage side of Transformer winding have less number of turns.
Description : Step-down transformer converts high voltage and low current into: (A) How voltage and high current (B) High voltage and low current (C) Low voltage and high current (D) None of the above
Last Answer : Step-down transformer converts high voltage and low current into: Low voltage and high current
Description : Why to calculate equivalent impedance referred to primary or secondary side?
Last Answer : Equivalent impedance is essential to be calculated because the electrical power transformer is an electric power system equipment, for estimating different parameters of electric power system ... referred to primary or equivalent circuit of transformer referred to secondary sides respectively.
Description : 21.The ordinary two winding transformer's primary and secondary windings always have A. different no of turns B. same size of copper wire C. a common magnetic circuit D. separate magnetic circuits
Last Answer : C. A common magnetic circuit
Description : An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V
Last Answer : An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V
Description : Explain about the open and short circuit tests on transformer?
Last Answer : A. Open circuit test (No load test) and short circuit test (full load test) are performed on a transformer to determine (i) Equivalent circuit of transformer (ii) Voltage ... determine copper loss in transformer at full load and parameters of approximate equivalent circuit of transformer.
Last Answer : The short circuit in any winding of the transformer is the result of impulse voltage.
Description : 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.
Description : 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.
Description : 49 The open circuit test is carried out in a transformer to find the A. Cu loss B. Core loss C. Total loss D. Insulation resistance
Last Answer : B. Core loss
Description : During open circuit test of a transformer?
Last Answer : During open circuit test of a transformer primary is supplied rated voltage.
Description : 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
Description : 47 Cross over windings are used in A. Low voltage side of high kVA rating transformers B. Current transformers C. High voltage side of high kVA rating transformers D. High voltage side of low kVA rating transformers
Last Answer : D. High voltage side of low kVA rating transformers
Description : 4 Helical coils can be used on A. Low voltage side of high kVA transformers B. High frequency transformers C. High voltage side of small capacity transformers D. High voltage side of high kVA rating transformers
Last Answer : A) low voltage side of high KVA transformer
Description : What is determined from short circuit test?
Last Answer : Copper loss
Description : During short circuit test iron losses are negligible because?
Last Answer : During short circuit test iron losses are negligible because the voltage applied on primary side is low.
Description : Does the transformer draw any current when its secondary is open?
Last Answer : Yes, no-load primary current.
Description : Does the transformer draw any current when secondary is open ? Why ?
Last Answer : Yes,it (primary) will draw the current from the main supply in order to magnetize the core and to supply iron and copper losses on no load . There will not be any current in the secondary since secondary is open
Description : Increasing the number of turns of wire on the secondary of a transformer will (A) Decrease the secondary current (B) Increase the primary current (C) Have no effect on the secondary current (D) Increase the secondary current
Last Answer : Increasing the number of turns of wire on the secondary of a transformer will Decrease the secondary current
Description : Which of the following conditions indicates a short circuited capacitor when checking its condition with an ohmmeter? A. The capacitor shows charging, but the final resistance reading is appreciably less ... moves quickly to the low resistance side of the scale, then slowly recedes toward infinity.
Last Answer : Answer: B