## Transformer MCQs Part 34

Electrical Engineering MCQ on Transformer No-load current in a transformer No-load current in a transformer Correct answer: 2. Lags behind the voltage by about 75° The winding of the transformer that has less cross-sectional area The winding of the transformer that has less cross-sectional area Correct answer: 1. High voltage winding During open circuit test of a … Read more

## Transformer MCQs Part 13

Transformer MCQs Part 13 The all-day efficiency of a lighting transformer is always _________ its power efficiency The all-day efficiency of a lighting transformer is always _________ its power efficiency: Less than Equal to Higher than None of these Correct answer: 1. Less than A 3000/150 V, 30 kVA transformer has 50 turns in secondary. … Read more

## Transformer MCQs Part 11

Transformer MCQs Part 11 A 40 Ω resistive load is to be impedance matched by transformer to a source with internal resistance of 4000 Ω . If open circuit voltage of source is 60 V. Then the secondary power in watts will be A 40 Ω is to be impedance matched by transformer to a … Read more

## Transformer MCQs Part 10

Transformer MCQs Part 10 The temperature rise of transformer is directly proportional to The temperature rise of transformer is directly proportional to: Apparent power Leakage reactance Reactive power All of these None of these Correct answer: 1. Apparent power Explanation: Two types of losses occurring in a transformer are: Iron losses: Depend upon voltage Copper … Read more

## Transformer MCQs Part 8

Transformer MCQs Part 8 Eddy current losses in transformer are directly proportional to: Eddy current losses in transformer are directly proportional to: Supply frequency Thickness of core lamination Square of thickness of core lamination Flex density in the core Correct answer: 3. Square of thickness of core lamination Which of following is correct for a … Read more

## Transformer MCQs Part 7

Transformer MCQs Part 7 Mutual flux in transformer remains constant at all loads since Mutual flux in transformer remains constant at all loads since: Leakage flux is small It uses iron core Applied voltage and frequency are constant None of these Correct answer: 3. Applied voltage and frequency are constant Certain transformer takes 0.4 A … Read more

## Which relay provides a signal before the fault [MCQ Question]

Electrical Engineering MCQ Question Statement: Which relay provide signal before the serious fault: Overcurrent relay Buchholz relay Undercurrent relay All of above Correct answer: 2. Buchholz relay Also read: Working of Protection Relays In case of the occurrence of incipient faults in transformers, the generated hydrogen gas tries to go into the conservator and gets … Read more

## How transformers are manufactured

In this video you’ll learn about manufacturing process of Large power Transformers as well as small and medium sized distribution transformers.

## Why noise is produced in Transformers

Audible noise is an effect primarily originating from the phenomenon of magnetostriction: the slight change of length exhibited by a ferromagnetic object when magnetized. The familiar “hum” heard around large power transformers is the sound of the iron core expanding and contracting at 120 Hz (twice the system frequency, which is 60 Hz in the United … Read more

## Why Large Power Transformers use Oil

Large power transformers have their core and windings submerged in an oil bath to transfer heat and muffle noise, and also to displace moisture which would otherwise compromise the integrity of the winding insulation. Heat-dissipating “radiator” tubes on the outside of the transformer case provide a convective oil flow path to transfer heat from the … Read more