Objective Questions on Transformer for Electrician Trade
| Sr. No. | Questions with options |
| 1 | Which type of transformer is used for high frequency application?
(a) Ring core transformer (b) Ferrite core transformer (c) Silicon steel core transformer (d) Grain oriented core transformer Ans – (b) |
| 2 | What is the function of conservator in transformer?
(a) Prevents the moisture entry (b) Transfers the heat to atmosphere (c) Allows to release internal pressure (d) Allows expansion of oil level due to load variation Ans –(d) |
| 3 | Which loss of transformer is determined by short circuit test?
(a) Copper loss (b) Windage loss (c) Hysteresis loss (d) Eddy current loss Ans – (a) |
| 4 | Calculate the voltage regulation in percentage of the transformer if the no load voltage is 240 volt and full load voltage is 220 volt?
(a) 7.7% (b) 8.3% (c) 8.71% (d) 9.09% Ans – (d) |
| 5 | What is the purpose of using laminated core in transformer?
(a) Reduce copper loss (b) Reduce hysteresis loss (c) Reduce mechanical loss (d) Reduce eddy current loss Ans –(d) |
| 6 | What is the condition for obtaining maximum efficiency from transformer?
(a) Copper loss> Iron loss (b) Copper loss< Iron loss (c) Copper loss = Iron loss (d) Copper loss = eddy current loss Ans- (c) |
| 7 | What is the function of top float switch of buccholz relay in transformer?
(a) Activate in moisture presence (b) Activate at overloading condition (c) Activate at open circuit condition (d) Activate at high temperature condition Ans – (b) |
| 8 | Why the core of current transformer is having low reactance and low core losses?
(a) To minimize the burden (b) To maintain constant output (c) To prevent high static shield (d) To minimize the error in reading Ans –(d) |
| 9 | How the error in reading of a potential transformer can be reduced?
(a) Using thin laminated core (b) Providing long magnetic path (c) Using high flux density material (d) Providing good quality core material Ans –(d) |
| 10 | Why the load is disconnected before the OFF load tap changing operation?
(a) To disconnect the tappings from neutral point (b) To disconnect the moving contact of the diverter (c) To avoid heavy sparking at the contact points (d) To provide an electrical isolation for the windings Ans – (c) |
| 11 | Which condition is absolutely essential for parallel operation of two transformers?
(a) Nature of load (b) Type of cooling (c) Phase sequence (d) Class of insulation used Ans – (c) |
| 12 | Which construction technique is used to reduce copper loss in larger transformers?
(a) Use of laminated core (b) By reducing core thickness (c) By using grain oriented core (d) Use stepped core arrangement Ans – (d) |
| 13 | Which transformer is used to measure high voltage installations?
(a) Pulse transformers (b) Ignition transformers (c) Potential transformers (d) Constant voltage transformers Ans – (c) |
| 14 | How does the moisture is controlled in breather fitted on power transformers?
(a) Using silica gel (b) Using transformer oil (c) Using sodium chloride (d) Using ammonium jelly Ans- (a) |
| 15 | Which power loss is assessed by open-circuit test on transformer?
(a) Hysteresis loss only (b) Eddy current loss only (c) Copper loss (d) Core loss Ans – (d) |
| 16 | Which is determined by the crackle test of transformer oil?
(a) Acidity (b) Moisture (c) Viscosity (d) Dielectric strength Ans – (b) |
| 17 | Which material is used to make core of power transformer?
(a) Soft iron (b) Rolled steel (c) Copper alloy (d) Cold rolled grain oriented Ans – (d) |
| 18 | What is the purpose of providing explosion vent in a power transformer?
(a) Air releasing (b) Heat releasing (c) Pressure releasing (d) Moisture releasing Ans – (c) |
| 19 | What is the function of buchholz relay in power transformer?
(a) Protection from high temperature (b) Protection from moisture entering in oil (c) Protection from pressure loading in tank (d) Protection from both overloading and short circuit Ans – (d) |
| 20 | Why primary of potential transformer is wound with thin wire and large number of turns?
(a) To offer high inductance (b) To obtain required voltage ratio (c) To regulate the primary current (d) To stabilize input and output voltage Ans – (a) |
| Published On – 1st June 2022 | |
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