Sobha Engineering Contracting Electrician Interview Questions and Answers

ELCB stands for Earth Leakage Circuit Breaker and MCB stands for Miniature Circuit Breaker.

• ELCB is a safety device used to protect against electrical shock caused by earth faults.

• MCB is a type of circuit breaker that automatically switches off electrical circuits during abnormal conditions.

• ELCB detects current leakage to earth and disconnects the circuit, while MCB protects against overloads and short circuits.

MCB (Miniature Circuit Breaker) provides overload protection by automatically switching off the circuit when current exceeds the rated capacity.

• MCB trips when current exceeds its rated capacity to prevent overheating and potential fire hazards.

• Overload protection is essential to protect electrical appliances and wiring from damage.

• Examples of MCB overload protection include tripping when too many devices are connected ...read more

An electrical panel with a braking system is a safety feature that automatically stops the flow of electricity in case of an emergency or malfunction.

• The braking system in an electrical panel is designed to prevent electrical accidents and protect both people and equipment.

• It works by detecting abnormal conditions such as short circuits, overloads, or ground faults, and immediately cutting off the power supply.

• This hel...read more

There are two types of electricity: direct current (DC) and alternating current (AC).

• Direct current (DC) flows in one direction and is commonly used in batteries and electronic devices.

• Alternating current (AC) constantly changes direction and is used in homes and businesses for powering appliances and lighting.

• Other types of electricity include static electricity, which is the buildup of electric charge on an object, a...read more

Ball lightning

• Ball lightning is a rare and mysterious atmospheric phenomenon.

• It appears as a glowing sphere of light that can move erratically and last for several seconds.

• It is considered dangerous due to its unpredictable behavior and potential to cause damage.

• Ball lightning has been reported to pass through walls, explode, and even cause fires.

• Scientists are still studying its nature and trying to understand its ori

The speed difference between stator's rotating magnetic field and rotor's rmf is called slip.

• The slip is necessary for inducing current in the rotor and producing torque.

• The slip is typically around 1-3% in most induction motors.

• Higher slip values can indicate issues with the motor such as overload or mechanical problems.

An induction motor is a type of AC motor where power is supplied to the rotor by electromagnetic induction.

• Induction motors are commonly used in various applications such as industrial machinery, pumps, fans, and compressors.

• They do not require brushes to transfer power to the rotor, making them more reliable and maintenance-free compared to brushed DC motors.

• The speed of an induction motor is determined by the frequen...read more

Synchronisation is the process of coordinating multiple systems or devices to work together in harmony.

• Synchronisation ensures that different components or processes are aligned in time.

• It is commonly used in electrical systems to ensure that multiple generators are running in phase with each other.

• In data communication, synchronisation is important for ensuring that data is transmitted and received at the correct timi...read more

The speed of a rotor with respect to the stator magnetic field in an induction motor is known as slip speed.

• The slip speed is the difference between the synchronous speed of the rotating magnetic field in the stator and the actual speed of the rotor.

• It is necessary for the rotor to operate at a speed slightly slower than the synchronous speed in order to induce current and generate torque.

• The slip speed allows the roto...read more

Slip is the difference between synchronous speed and actual rotor speed in an induction motor. Per unit slip is the slip expressed as a fraction of synchronous speed.

• Slip is the difference between synchronous speed (speed of the rotating magnetic field) and the actual rotor speed in an induction motor.

• Per unit slip is the slip expressed as a fraction of synchronous speed, typically denoted as a percentage.

• For example, ...read more