___ is the rms value of the total current comprising the AC and DC components of the current in the circuit breaker pole at the instant of contact separation.

Symmetrical breaking current:
It is the rms value of a a.c component of the current in the pole at the instant of contact separation.

Asymmetrical breaking current:
It is the rms value of the total current comprising the a.c and d.c components of the current in the pole at the instant of contact separation.

Which among the following are included in the two part tariff?
i. Fixed charges
ii. Running charges
iii. Semi fixed charges

Two-part tariff:
In this type of tariff, the total bill is divided into two parts.
The first one is the fixed charge and the second is the running charge.
The fixed charge is because of the maximum demand and the second charge depends on the energy consumption by the load.

Match the following

Bus Type - Known Parameter - Unknown Parameter
Load Bus -P, Q - V, phase angle
Generator Bus - P, V (magnitude) - Q, Voltage phase angle
Slack Bus Voltage - magnitude and phase angle - P, Q

Insulation Power Factor testing on an oil-filled transformer is not helpful in determining ___

A form of AC testing that applies voltage and measures the leakage/loss current of electrical insulation.
It is a type of insulation testing used to evaluate the integrity of electrical insulation.

The single line diagram of the simple system is shown in figure the corresponding reactance diagram is

Simple logic of reactance diagram is that simplified equivalent circuit of power system in which the various components of power system are represented by their reactance.
The reactance diagram can be obtained from impedance diagram if all the resistive components are neglected.
So, from figure each of the component is represented by its reactance.

A transformer designed for operation at 60 Hz supply is working at 50 Hz supply system without changing its voltage and current ratings. Compared to the full load efficiency at 60 Hz, the full load transformer efficiency at 50 Hz.