Question

At constant voltage how is frequency affected by flux?

(a) decreases with an increase in flux

(b) increases with a decrease in flux

(c) remains constant

(d) depends on the current

This question was posed to me in an international level competition.

Enquiry is from Characteristics of Potential Transformers topic in portion Extension of Instrument Ranges of Electrical Measurements

Answer 1

The correct answer is (b) increases with a decrease in flux

For explanation: When frequency is increased at a constant voltage, the flux decreases. Voltage ratio decreases as the magnetizing and iron loss components of current are reduced.