JSW Ispat Steel Junior Engineer Electrical Interview Questions and Answers

A transformer is a device that transfers electrical energy between two or more circuits through electromagnetic induction.

• Consists of two coils of wire (primary and secondary) wrapped around a core

• Primary coil receives electrical energy and creates a magnetic field

• Magnetic field induces a voltage in the secondary coil, transferring energy

• Used to step up or step down voltage in power distribution systems

A current transformer is a type of instrument transformer used to measure alternating current.

• Used to step down high currents to a lower, more manageable level for measurement

• Consists of a primary winding and a secondary winding

• Secondary winding is connected to measuring instruments or protective relays

• Provides accurate current measurement without affecting the main circuit

Ideal transformer is theoretical with no losses, while practical transformer has losses due to resistance, leakage flux, etc.

• Ideal transformer has no losses, while practical transformer has losses due to resistance, leakage flux, hysteresis, and eddy currents

• Ideal transformer has infinite efficiency, while practical transformer has efficiency less than 100%

• Ideal transformer has no voltage drop, while practical transfor...read more

Voltage is the difference in electric potential between two points in a circuit, measured in volts.

• Voltage is the force that pushes electric current through a circuit.

• It is measured in volts (V).

• Higher voltage means more potential energy for electrons to flow.

• Voltage can be compared to water pressure in a pipe - higher pressure (voltage) means faster flow (current).

Turn ratio is the ratio of the number of turns in the primary winding to the number of turns in the secondary winding of a transformer.

• Turn ratio determines the voltage transformation ratio in a transformer.

• It is calculated by dividing the number of turns in the primary winding by the number of turns in the secondary winding.

• For example, if a transformer has 100 turns in the primary winding and 200 turns in the seconda

The emf equation of a transformer relates the induced voltage to the number of turns in the primary and secondary coils.

• The emf equation of a transformer is given by: E = N*dΦ/dt, where E is the induced voltage, N is the number of turns, and dΦ/dt is the rate of change of magnetic flux.

• This equation shows that the induced voltage in a transformer is directly proportional to the number of turns in the coils and the rate...read more

Current is the flow of electric charge in a circuit.

• Current is measured in Amperes (A).

• It is the rate of flow of electric charge past a point in a circuit.

• Current can be either direct current (DC) or alternating current (AC).

• Examples: A light bulb draws current from a power source to produce light. A fan motor requires current to spin.

A potential transformer is a type of instrument transformer used to step down high voltage to a lower, safer voltage for measurement or control purposes.

• Used to step down high voltage to a lower voltage for measurement or control purposes

• Provides accurate voltage measurements for meters and relays

• Commonly used in power systems for protection and metering applications

Inductance is the property of an electrical circuit that opposes changes in current flow.

• Inductance is measured in Henrys (H)

• It is caused by the magnetic field generated when current flows through a conductor

• Inductors are components that are designed to have a specific inductance value

• Inductance is used in circuits to store energy in the form of a magnetic field

Capacitance is the ability of a system to store an electric charge.

• Capacitance is measured in farads (F).

• It is the ability of a capacitor to store energy in an electric field.

• Capacitance depends on the geometry of the capacitor and the dielectric material between the plates.

• Capacitance is calculated as C = Q/V, where C is capacitance, Q is charge, and V is voltage.

The unit of inductor is Henry (H)

• The unit of inductor is named after American scientist Joseph Henry

• It is represented by the symbol 'H'

• 1 Henry is equal to 1 volt-second per ampere