300+ Electrical Technician Interview Questions and Answers

Preventive and corrective maintenance of various electrical equipment including breakers, motors, transformers, switches, relays, and testing/calibration of protections.

• Preventive maintenance of H.V & LV breakers, motors, transformers, switches, etc.

• Corrective maintenance of HV/MV/LV switchgears, breakers, cubicles, etc.

• Testing and calibration of various protection relays for motors, transformers, generators.

• Transformer oil BDV test, thermal scanning, earth fault and predicti...read more

The Electrical Technician is responsible for preventive and corrective maintenance of various high and low voltage equipment and testing/calibration of protection relays.

• Responsible for maintenance of motors, transformers, breakers, switches, and other equipment

• Testing and calibration of protection relays for motors, transformers, and generators

• Termination of high voltage motors, cable erection, installation, and load testing

• Maintenance of battery banks and UPS for auxiliary ...read more

Transformers are electrical devices that transfer electrical energy between two or more circuits through electromagnetic induction.

• Transformers are used to step up or step down voltage levels in electrical power transmission and distribution systems.

• They consist of two or more coils of wire, known as windings, which are wound around a core made of magnetic material.

• The primary winding is connected to the power source, while the secondary winding is connected to the load.

• Trans...read more

Step up and step down transformers are used to increase or decrease the voltage in electrical systems.

• Step up transformers increase the voltage from the input to the output.

• Step down transformers decrease the voltage from the input to the output.

• Step up transformers have more turns in the secondary coil than in the primary coil.

• Step down transformers have fewer turns in the secondary coil than in the primary coil.

• Step up transformers are used in power transmission to increase...read more

R, Y, B phases are the three phases of AC power supply. They differ in their phase angle and voltage level.

• R phase has a phase angle of 0 degrees and is usually connected to the red wire.

• Y phase has a phase angle of 120 degrees and is usually connected to the yellow wire.

• B phase has a phase angle of 240 degrees and is usually connected to the blue wire.

• The voltage level of each phase is the same, but they are out of phase with each other.

• The three phases are used to power thr...read more

Phase sequence is crucial in 3 phase systems and 6 lead motor connections in Delta.

• Phase sequence determines the direction of rotation of the motor.

• In a 3 phase system, R Y B is the correct phase sequence.

• In a 6 lead motor connection in Delta, the phase sequence must be maintained to ensure proper functioning.

• Incorrect phase sequence can lead to motor damage and malfunction.

• Phase sequence can be checked using a phase sequence meter.

Yes, I have been involved in electrical installation before.

• I have worked on various electrical installation projects during my previous job.

• I have experience in installing electrical systems in residential and commercial buildings.

• I am familiar with reading and interpreting electrical blueprints and diagrams.

• I have knowledge of electrical codes and regulations.

• I have successfully completed electrical installation projects within deadlines.

• I have worked with a team of electri...read more

To protect myself from electrical shocks while working, I follow safety protocols and use personal protective equipment (PPE).

• Always wear insulated gloves and safety glasses when working with electricity.

• Ensure that all equipment is properly grounded before starting any work.

• Use lockout/tagout procedures to de-energize circuits and prevent accidental re-energization.

• Avoid working on live circuits whenever possible.

• Regularly inspect and maintain tools and equipment to ensure t...read more

A capacitor is an electronic component that stores and releases electrical energy. It is a passive component.

• A capacitor consists of two conductive plates separated by an insulating material, known as a dielectric.

• When a voltage is applied across the plates, the capacitor stores electrical charge.

• Capacitors are commonly used in electronic circuits for various purposes, such as smoothing power supply voltages, filtering signals, and storing energy.

• They can be found in devices ...read more

Periodic maintenance of batteries is crucial for their longevity and optimal performance.

• Check the battery terminals for corrosion and clean them if necessary

• Inspect the battery case for any cracks or damage

• Ensure that the battery is securely fastened in place

• Check the electrolyte level and top up with distilled water if required

• Test the battery voltage and recharge if necessary

In series, voltage adds up while current remains the same. In parallel, voltage remains the same while current adds up.

• In series, batteries are connected end-to-end, positive to negative. In parallel, batteries are connected positive to positive and negative to negative.

• Series connection increases voltage but does not increase current. Parallel connection increases current but does not increase voltage.

• Series connection is used to increase voltage for high-power applications ...read more

Transformers, DGs, chillers, air compressors, and electrical panels control power distribution and equipment operation.

• Transformers step up or down voltage to match equipment needs.

• DGs provide backup power in case of outages.

• Chillers cool water for air conditioning systems.

• Air compressors provide compressed air for equipment operation.

• Electrical panels distribute power to equipment and control its operation.

Single phase and three phase are two types of electrical power distribution systems.

• Single phase has one live conductor and one neutral conductor, while three phase has three live conductors and one neutral conductor.

• Single phase is commonly used in residential and small commercial applications, while three phase is used in industrial and large commercial applications.

• Single phase power supply is suitable for low power loads, while three phase power supply is suitable for hig...read more

FUSE, MCB, ELCB, and RCCB are all electrical protection devices, but they differ in their functions and applications.

• FUSE is a simple device that protects electrical circuits from overloading or short-circuiting by melting and breaking the circuit.

• MCB (Miniature Circuit Breaker) is an automatic switch that trips and cuts off the power supply when there is an overload or short-circuit.

• ELCB (Earth Leakage Circuit Breaker) is a safety device that detects and cuts off the power s...read more

The question seems incomplete and unclear.

• The question lacks context and details.

• It is unclear what is being asked.

• More information is needed to provide an answer.

• The given information is not sufficient to solve the problem.

ACB and VCB breakers are both types of circuit breakers used in electrical systems, but they differ in their operating mechanisms.

• ACB stands for Air Circuit Breaker, while VCB stands for Vacuum Circuit Breaker.

• ACB breakers use air as the medium for arc extinction, while VCB breakers use vacuum.

• ACB breakers are typically used for low voltage applications, while VCB breakers are used for medium to high voltage applications.

• ACB breakers are more commonly found in industrial and ...read more

Cable continuity can be checked using a multimeter or a cable tester.

• Use a multimeter to measure the resistance between the two ends of the cable. A low resistance value indicates continuity.

• Connect one end of the cable to the multimeter's positive lead and the other end to the negative lead.

• If the multimeter shows a high resistance or an open circuit, there is a break in the cable.

• Alternatively, a cable tester can be used to check continuity by sending a signal through the c...read more

Electrical maintenance involves the inspection, repair, and upkeep of electrical systems and equipment.

• Electrical maintenance ensures the safe and efficient operation of electrical systems.

• It involves regular inspections to identify and address potential issues before they become major problems.

• Maintenance tasks may include cleaning, lubricating, and replacing components.

• Examples of electrical maintenance include testing and replacing faulty wiring, inspecting and repairing c...read more

MSEDCL stands for Maharashtra State Electricity Distribution Company Limited. It is responsible for electricity distribution in Maharashtra.

• MSEDCL is a government-owned company that distributes electricity to various parts of Maharashtra.

• It was formed in 2005 after the restructuring of the Maharashtra State Electricity Board.

• MSEDCL is responsible for maintaining and upgrading the distribution network, billing, and collection of electricity charges.

• It also provides new connect...read more

Single-phase and three-phase supply differ in the number of power lines and voltage waveform.

• Single-phase supply has one power line and a sinusoidal voltage waveform.

• Three-phase supply has three power lines and a balanced sinusoidal voltage waveform.

• Single-phase supply is commonly used in residential applications.

• Three-phase supply is used in industrial and commercial applications.

• Three-phase supply provides higher power capacity and efficiency compared to single-phase supply...read more

PLC working processes include sink and source types.

• PLC input modules can be either sink or source type.

• Sink type modules have a common negative terminal and accept positive signals.

• Source type modules have a common positive terminal and output positive signals.

• Output modules can also be sink or source type.

• Sink type output modules provide a path to negative terminal.

• Source type output modules provide a path to positive terminal.

FET (Field Effect Transistor) is a type of transistor that uses an electric field to control the flow of current.

• FETs are voltage-controlled devices, meaning they are controlled by the voltage applied to their terminals.

• There are two main types of FETs: MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) and JFET (Junction Field Effect Transistor).

• MOSFETs are widely used in various electronic devices, such as computers, smartphones, and power amplifiers.

• They have high ...read more

Current is the flow of electric charge in a circuit.

• Current is measured in amperes (A).

• It is the rate at which electric charge flows through a conductor.

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

• In a DC circuit, the current flows in one direction only.

• In an AC circuit, the current changes direction periodically.

• Current is caused by the movement of electrons or other charged particles.

• It is essential for the operation of electrical devices and syste...read more

RCCB stands for Residual Current Circuit Breaker. It is used in electrical systems to protect against electric shock and fire hazards.

• RCCB is a type of circuit breaker that detects imbalances in the electrical current flowing through a circuit.

• It quickly disconnects the power supply when it detects a leakage current, which could indicate a fault or electric shock hazard.

• RCCBs are commonly used in residential, commercial, and industrial electrical installations to enhance safe...read more

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Safety measures are important to prevent accidents and ensure proper functioning of transformers.

• A transformer is used to step up or step down voltage levels in electrical systems.

• It consists of two or more coils of wire, known as windings, which are wound around a core made of magnetic material.

• The primary winding receives electrical energy f...read more

The interview questions cover motor starters, layout, power factor, troubleshooting with megger, and fault finding.

• Motor starters are used to control the starting and stopping of motors.

• There are different types of motor starters such as direct-on-line, star-delta, and soft starters.

• The power layout of starters includes power supply, motor, and control circuit.

• The control layout of starters includes start, stop, and overload protection.

• Power factor is the ratio of real power ...read more

Off load and on load OLTC and RTCC panels are used in electrical systems for voltage regulation and control.

• Off load OLTC panel is used to change the tap position of the transformer when it is not energized.

• On load OLTC panel is used to change the tap position of the transformer while it is energized.

• RTCC (Remote Tap Changing Control) panel is used to remotely control the tap changing operation of the transformer.

• Off load OLTC panel is typically used in situations where the t...read more

Capacitor is connected in across rectified output d.c. supply to filter out the AC component.

• Capacitor blocks the DC component and allows only AC component to pass through.

• It smoothens the output voltage by reducing the ripple.

• It helps in reducing the noise and interference in the circuit.

• The value of the capacitor depends on the load current and the frequency of the AC component.

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

• Transformer rating refers to the maximum power that a transformer can handle.

• Transformer make refers to the manufacturer or brand of the transformer.

• Transformer safety involves proper insulation, grounding, and protection against electrical faults.

• Transformer protection includes measures such as over-temperature protection (OTI) and winding tem...read more

Yes, cable size estimation is based on the required load and can be calculated using various formulas.

• Cable size estimation is important to ensure safety and efficiency of electrical systems

• The required load can be calculated by adding up the wattage of all the devices that will be connected to the cable

• The cable size can then be estimated using formulas such as the voltage drop formula or the NEC ampacity tables

• Factors such as distance, temperature, and number of conductors ...read more

The oven conveyor running speed at Domino's varies depending on the specific oven model and the type of pizza being cooked.

• The oven conveyor speed is typically set to ensure that pizzas are cooked evenly and efficiently.

• Different types of pizzas may require different conveyor speeds to achieve the desired level of doneness.

• The conveyor speed can be adjusted manually or automatically based on the oven's programming.

• Domino's may have different oven models in different locations...read more

The statement refers to Kirchhoff's Current Law which states that the sum of currents entering a node is equal to the sum of currents leaving the node.

• Kirchhoff's Current Law is a fundamental law in electrical engineering

• It is also known as Kirchhoff's First Law or KCL

• The law applies to any node in an electrical circuit

• The algebraic sum of currents entering the node is equal to the algebraic sum of currents leaving the node

• The law is based on the principle of conservation of ...read more

A capacitor is an electronic component that stores and releases electrical energy. A transistor is a semiconductor device that amplifies or switches electronic signals. A variable frequency drive is an electronic device that controls the speed of an electric motor.

• A capacitor is used to store and release electrical energy.

• It consists of two conductive plates separated by an insulating material called a dielectric.

• When a voltage is applied across the plates, one plate accumula...read more

To change AC to DC current in a DC motor, a rectifier is used. The commutator in a DC motor helps in converting the current direction.

• AC to DC conversion in a DC motor is achieved using a rectifier.

• The rectifier converts the alternating current (AC) into direct current (DC) by using diodes.

• The commutator in a DC motor is a rotary electrical switch that helps in reversing the direction of current flow in the armature winding.

• It consists of a set of copper segments connected to...read more

There are several types of motor protection relays used in electrical systems.

• Motor overload protection relays

• Motor thermal protection relays

• Motor phase loss protection relays

• Motor short circuit protection relays

• Motor underload protection relays

• Motor earth fault protection relays

• Motor stall protection relays

The number of starters used in our company varies depending on the specific projects and requirements.

• The number of starters used in our company is not fixed and can vary from project to project.

• We use starters for various electrical equipment such as motors, pumps, and compressors.

• The quantity of starters required depends on the size and complexity of the electrical systems.

• We follow industry standards and guidelines to determine the appropriate number of starters for each a...read more

The company generates 500 MW of energy.

• The company's energy generation capacity is 500 MW.

• The company has a power plant that generates 500 MW of energy.

• The energy output of the company is 500 MW.

• The company's energy generation is sufficient to power a large city.

The first thing to do in case of a hazard is to ensure the safety of yourself and others.

• Assess the situation to determine the nature and extent of the hazard.

• Alert others in the vicinity about the hazard.

• Follow safety protocols and procedures to mitigate the hazard.

• Contact emergency services if necessary.

• Evacuate the area if instructed to do so.

Check for clogs in the fuel line, inspect the injector for damage, clean or replace the injector if necessary.

• Inspect the fuel line for any clogs or blockages

• Check the injector for any damage or malfunction

• Clean the injector using appropriate tools and techniques

• If cleaning doesn't work, consider replacing the injector

• Ensure proper fuel flow and pressure to the injector

A circuit breaker is an electrical switch that automatically interrupts the flow of current in a circuit.

• It is designed to protect electrical circuits from damage caused by excessive current or short circuits.

• When the current exceeds a certain limit, the circuit breaker trips and interrupts the flow of electricity.

• It can be manually reset after tripping or may automatically reset once the fault is cleared.

• Circuit breakers are commonly used in residential, commercial, and indu...read more

To determine if a motor coil is damaged, check for continuity using a multimeter and inspect for physical damage.

• Use a multimeter to check for continuity in the coil windings

• Inspect the coil for any physical damage such as burns, breaks, or discoloration

• Compare the resistance readings with the manufacturer's specifications

• Check for any loose connections or faulty components in the motor circuit

• Consider testing other components such as the capacitor or start switch

The question is about the concept of subtraction.

• The question is describing the process of subtraction.

• Taking 5 goods out of 13 means subtracting 5 from 13.

• The result of subtracting 5 from 13 is 8.

Electricity is the flow of electrons while electronics deals with the control of the flow of electrons.

• Electricity is a natural phenomenon while electronics is a man-made technology.

• Electricity is the basic form of energy while electronics is a branch of science that deals with the study of electronic devices and their applications.

• Electricity is used to power electronic devices.

• Examples of electronic devices include computers, smartphones, televisions, and radios.

• Examples of...read more

An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current.

• Alternators are commonly used in vehicles to charge the battery and power the electrical system

• Types of alternators include single-phase, three-phase, synchronous, and asynchronous

• Single-phase alternators are used in small appliances and power tools

• Three-phase alternators are used in industrial applications and power plants

• Synchronous alternators ar...read more

The color code of resistance is a system used to identify the resistance value and tolerance of resistors.

• The color code consists of bands of different colors that represent specific values and tolerances.

• The first two bands indicate the significant digits of the resistance value.

• The third band represents the multiplier or the number of zeros to be added to the significant digits.

• The fourth band indicates the tolerance of the resistor.

• For example, a resistor with bands of bro...read more

Possible problems in starter and motor causing motor not to start.

• Check if there is power supply to the starter

• Inspect for any loose connections or damaged wires in the starter circuit

• Examine the starter motor for any mechanical issues such as worn out brushes or bearings

• Verify if the motor itself is faulty by checking for continuity and resistance in windings

The number of transformers depends on the specific context and location.

• The number of transformers can vary depending on the size and purpose of the electrical system.

• In a residential area, there may be one transformer serving multiple houses.

• In a commercial or industrial setting, there may be multiple transformers to meet the power demands.

• Transformers can also be found in power substations, where they step up or step down the voltage for transmission and distribution purpos...read more