When two alternating quantities of the same frequency have different zero points, they are said to have a phase difference. The angle between zero points is the angle of phase difference φ.
In the above-given question, the frequency of voltage and current is different so we can’t calculate the phase difference between them
In the PMMC type instrument, the deflection is directly proportional to the current flowing through the instrument, we get a uniform scale for the instrument. It gives a uniform scale of upto 270° or more.
Td ∝ I
The slow but continuous rotation of the energy meter (Induction type) when only the pressure coil is excited and no current is flowing through the current coil is called creeping. This error may be due to excessive friction compensation, excessive voltage supply, stray magnetic field, etc.
In order to prevent creeping at no-load, two holes of the same radius are drilled in the disc on the opposite side of the spindle.
Synchronous motors are not self-starting. The DC source is applied to the rotor of the synchronous Motor.