Tap Changing Transformers - Transformers MCQs

Explanation: Tap-changing Transformers : The change of voltage is affected by changing the numbers of turns of the transformer provided with taps

Explanation: There are two types of tap-changing transformers : Off-load tap changing transformer and On-load tap changing transformer

Explanation: Off-load tap-changing transformer : In this method, the transformer is disconnected from the main supply when the tap setting is to be changed.

Explanation: The tap setting is usually done manually.

Explanation: While tapping, two essential conditions are to be fulfilled : The load circuit should not be broken to avoid arcing and prevent the damage of contacts and No parts of the windings should be short–circuited while adjusting the tap.

Explanation: Adjustment is normally carried out by off-circuit tap changing, the common range being 5% in 2.5% steps. Daily and short-time control or adjustment is carried out by means of on-load tap changing gear, which makes this application easier.

Explanation: The principal tapping is one to which the rating of the winding is related. A positive tapping means more turns and a negative tapping implies less turns than those of the principal tap. Tap changing may be achieved by three conditions

Explanation: On-load tap changers are used to change the turn ratio of transformer to regulate system voltage while the transformer is delivering load. With the introduction of on-load tap changer, the operating efficiency of electrical system gets considerably improved

Explanation: True, During the tap change, only half of the reactance which limits the current is connected in the circuit.

Explanation: The main components are an automatic voltage regulator, a time delay relay, and compounding elements. The time delay here, prevents unwanted initiation of a tap change by a small transient voltage fluctuation. It may be set for a delay upto 1 min.