Electrical and electronics measurements miscellaneous Difficult Questions and Answers

Electrical and electronics measurements miscellaneous

A current transformer has a rating of 1000/5 A. Its magnetizing current and loss component of exciting current are 10 A and 6 A respectively. The phase angle between secondary winding induced voltage and current is 30∠. The phase angle error of the transformer at rated current is

A current transformer has a rating of 100/5 A. Its magnet izing and loss component of excit ing current are 10 A and 0.6 A respectively and secondary winding burden is purely resistive, its transformation ratio at rated current is

A 4-range milliammeter having ranges of 0 – 10 mA, 0 – 50 mA, 0 – 100 mA and 0 – 500 mA. It is used for measurement of current whose magnitude is not known. In order to prevent damage to the instrument the selector switch of the ammeter should be first placed at

A PMMC instrument produces a deflection of 90° when a current 2 mA passes through its moving coil. The instrument is spring controlled. Supposing the instrument is redesigned with its spring constant as before, and its permanent magnet is replaced with a new permanent magnet which reduces twice the flux density as before, what would be the deflection if a current of 1 mA is passed through the coil? The other features of the PMMC instrument remain the same.