100+ Diploma Electrical Engineer Interview Questions and Answers

Star delta connection is used to start high power motors with reduced starting current and torque.

• Reduces starting current and torque

• Used for high power motors

• Improves motor efficiency

• Reduces voltage drop during starting

• Reduces stress on motor windings

• Example: Starting a large induction motor in an industrial setting

Different types of cables are used for power transmission, including overhead lines, underground cables, and submarine cables.

• Overhead lines are commonly used for power transmission over long distances.

• Underground cables are used in urban areas where overhead lines are not feasible.

• Submarine cables are used for power transmission between islands or across bodies of water.

• Different types of cables, such as aluminum cables and copper cables, are used based on the specific requi...read more

There are three types of motors in electrical systems: synchronous, asynchronous (induction), and special motors.

• Asynchronous motors include squirrel cage and slip ring induction motors.

• Special motors include universal, stepper, brushless DC, and servo VFD motors.

• Synchronous motors are used in applications where constant speed is required, while asynchronous motors are used in most industrial applications.

• Special motors have unique features such as high torque, precise contro...read more

Generators and alternators are both electrical machines that convert mechanical energy into electrical energy, but they differ in their construction and working principles.

• Generators produce direct current (DC) while alternators produce alternating current (AC).

• Generators use a commutator and brushes to convert mechanical energy into electrical energy, while alternators use slip rings and brushes.

• Generators are typically used in small-scale applications, such as portable powe...read more

Yes, there are different types of wires used in transmission.

• The most common types of wires used in transmission are copper, aluminum, and steel-cored aluminum.

• Copper wires are the most efficient and expensive, while aluminum wires are less efficient but more affordable.

• Steel-cored aluminum wires are used for long-distance transmission as they have high tensile strength.

• Other types of wires used in transmission include ACSR (Aluminum Conductor Steel Reinforced) and AAC (All A...read more

The neutral wire carries current back to the source, while the earth wire provides a path for electrical faults to safely discharge.

• Neutral wire carries current back to the source

• Earth wire provides a path for electrical faults to safely discharge

• Neutral wire is typically colored white or gray

• Earth wire is typically colored green or green with yellow stripes

• Neutral wire is connected to the grounding system at the main electrical panel

• Earth wire is connected to the grounding e...read more

The number of earthing required for commencing a transformer depends on the type and size of the transformer.

• The number of earthing required for a transformer depends on its rating and the local electrical regulations.

• In general, a single earthing electrode is sufficient for small transformers with ratings up to a few hundred kVA.

• For larger transformers, multiple earthing electrodes may be required to ensure proper grounding.

• The exact number of earthing electrodes and their s...read more

Substations are used in distribution and transmission lines to control voltage levels, protect equipment, and facilitate power transfer.

• Substations help in stepping up or stepping down the voltage levels as required.

• They provide a centralized location for monitoring and controlling the flow of electricity.

• Substations house transformers, circuit breakers, and other equipment for voltage regulation and protection.

• They enable power transfer between different transmission lines o...read more

A fuse is a one-time use device that melts when overloaded while a breaker can be reset and reused.

• A fuse needs to be replaced after it melts while a breaker can be reset

• A fuse is cheaper than a breaker

• A fuse reacts faster to overloads than a breaker

• A breaker can handle higher current loads than a fuse

• Examples of fuses include glass tube fuses and cartridge fuses while examples of breakers include thermal-magnetic and ground fault circuit interrupters (GFCI)

The acceptable current for humans depends on various factors such as duration, frequency, and pathway.

• The acceptable current for humans is typically below 1 mA for low-frequency currents.

• For high-frequency currents, the acceptable current is lower, usually below 0.1 mA.

• The duration of exposure also plays a significant role in determining the acceptable current.

• The pathway of the current through the body, such as hand-to-hand or hand-to-foot, affects the acceptable current.

• Fac...read more

Induction motors run at high speed at no load conditions

• Induction motors

• Asynchronous motors

• Squirrel cage motors

VCB stands for Vacuum Circuit Breaker. It is a type of electrical switchgear used for protecting electrical circuits from overloads and short circuits.

• VCB uses vacuum as the arc quenching medium instead of oil or air.

• It is installed in high voltage power systems, such as substations and power plants.

• VCBs are commonly used in distribution networks, generator circuits, and transformer circuits.

• They provide reliable and efficient protection against electrical faults.

• Examples of ...read more

There are mainly two types of solar panel installation: On-grid and Off-grid.

• On-grid installation is connected to the main power grid and excess energy can be sold back to the utility company.

• Off-grid installation is not connected to the main power grid and requires battery storage to store excess energy.

• Other types include ground-mounted, roof-mounted, and pole-mounted installations.

• Installation methods can also vary depending on the type of roof or ground surface.

Siemens is an electrical manufacturing company that produces a wide range of electrical products and solutions for various industries.

• Siemens is a global company that produces electrical products and solutions for industries such as energy, healthcare, and transportation.

• Their products include power generation equipment, automation systems, medical imaging equipment, and more.

• Siemens is known for their innovative technologies and commitment to sustainability.

• In the electrical...read more

Transformers cannot operate on DC supply due to the absence of changing magnetic field required for induction.

• Transformers work on the principle of electromagnetic induction, which requires a changing magnetic field.

• DC supply produces a constant magnetic field, which does not induce a voltage in the secondary coil of the transformer.

• AC supply, on the other hand, produces a changing magnetic field, allowing for induction and voltage transformation.

• Operating a transformer on DC...read more

A clamp meter is a tool used to measure electrical current without the need to disconnect the circuit, while a teco meter is used to measure the speed of an electric motor. Capacitance is the ability of a component to store electrical charge.

• Clamp meter is used to measure electrical current in a conductor without the need for direct contact.

• Teco meter is used to measure the speed of an electric motor.

• Capacitance is the ability of a component to store electrical charge, measur...read more

An electrical machine is a device that converts electrical energy into mechanical energy or vice versa. Ohm's Law relates voltage, current, and resistance. KVL and KCL are laws used in circuit analysis.

• Electrical machine is a device that converts electrical energy into mechanical energy or vice versa

• Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance of the conduct...read more

Primary connection sequence: H1-H2, Secondary connection sequence: X1-X2

• Primary connection sequence is typically H1-H2

• Secondary connection sequence is typically X1-X2

• The primary winding is connected to the supply voltage, while the secondary winding is connected to the load

• The connection sequence may vary depending on the transformer manufacturer and design

• Proper connection sequence is crucial for the transformer to function correctly

Motors and generators are electrical machines that convert electrical energy into mechanical energy and vice versa. PCB and soldering are components used in electronic circuits.

• Motors convert electrical energy into mechanical energy to produce motion.

• Generators convert mechanical energy into electrical energy.

• PCB (Printed Circuit Board) is a board made of insulating material with conductive pathways etched onto it to connect electronic components.

• Soldering is the process of j...read more

AC and DC are two types of electrical current. There are two types of transformers - step-up and step-down.

• AC stands for alternating current and DC stands for direct current

• AC changes direction periodically while DC flows in one direction

• Step-up transformers increase voltage while step-down transformers decrease voltage

• Transformers are used to transfer electrical energy from one circuit to another

• Examples of AC devices include household appliances and power grids, while examp...read more

There are several types of transformers used in electrical engineering.

• Power transformers

• Distribution transformers

• Instrument transformers

• Auto transformers

• Isolation transformers

• Step-up transformers

• Step-down transformers

There are no specific types of beakers used in electrical engineering.

• There are no beakers specifically used in electrical engineering.

• Beakers are commonly used in chemistry labs for measuring and mixing liquids.

• In electrical engineering, other types of equipment like multimeters, oscilloscopes, and power supplies are used.

Maintenance equipment for transformers include oil filtration systems, temperature sensors, and insulation testers.

• Oil filtration systems to remove impurities and extend the life of transformer oil

• Temperature sensors to monitor the temperature of the transformer and prevent overheating

• Insulation testers to check the insulation resistance of the transformer

• Dissolved gas analysis equipment to detect any faults in the transformer

• Bushings and tap changers for regular maintenance ...read more

Stationary armature and rotating field system offers advantages like simplified construction, reduced maintenance, and improved efficiency.

• Simplified construction: Stationary armature allows for a simpler design with fewer moving parts, reducing the chances of mechanical failure.

• Reduced maintenance: With the armature stationary, there is less wear and tear on the components, leading to lower maintenance requirements.

• Improved efficiency: The rotating field system allows for be...read more

The question is asking for knowledge about all types of electrical systems.

• Knowledge of different types of electrical systems such as AC, DC, single-phase, three-phase, etc.

• Understanding of electrical components and their functions, such as resistors, capacitors, transformers, etc.

• Familiarity with electrical codes and regulations.

• Ability to read and interpret electrical schematics and diagrams.

• Troubleshooting skills to identify and fix electrical faults.

• Knowledge of electrica...read more

Renewable energy sources are sources of energy that are replenished naturally, such as sunlight, wind, and water. Non-renewable energy sources are sources that cannot be easily replenished, such as fossil fuels.

• Renewable energy sources include solar power, wind power, hydropower, and geothermal energy

• Non-renewable energy sources include coal, oil, and natural gas

• Renewable energy is sustainable and environmentally friendly, while non-renewable energy contributes to pollution a...read more

A transformer is an electrical device that transfers electrical energy from one circuit to another through electromagnetic induction.

• Transformers are used to change the voltage level of an alternating current (AC) power supply.

• They consist of two coils of wire, known as the primary and secondary windings, wrapped around a magnetic core.

• When an AC voltage is applied to the primary winding, it creates a magnetic field that induces a voltage in the secondary winding.

• Transformers...read more

Transformers cannot be measured in kW because they do not consume power, they only transfer it.

• Transformers do not have any moving parts or internal power losses, so they do not consume power themselves

• The power rating of a transformer is given in kVA (kilovolt-amperes) which represents the maximum amount of power it can transfer

• The power factor of the load connected to the transformer determines the actual power in kW that is being used

To resolve an electrical issue, identify the problem, troubleshoot, and implement appropriate solutions.

• Identify the specific electrical issue

• Inspect the affected equipment or circuit

• Check for loose connections or damaged components

• Use appropriate testing equipment to diagnose the problem

• Troubleshoot by following electrical diagrams or manuals

• Implement necessary repairs or replacements

• Ensure proper safety measures are followed

• Test the repaired system to verify functionality

As a technical support, I provide prompt and efficient solutions to customer's electrical problems.

• Listen to the customer's problem and ask relevant questions to understand the issue

• Provide step-by-step instructions to troubleshoot the problem

• Offer remote assistance or schedule an on-site visit if necessary

• Ensure customer satisfaction by following up after the issue has been resolved

A CT transformer, also known as a current transformer, is an electrical device used to measure alternating current (AC) by stepping down the current to a lower value.

• CT transformers are commonly used in power systems to measure high currents without directly connecting measuring instruments to the circuit.

• They consist of a primary winding, which carries the current to be measured, and a secondary winding, which is connected to the measuring instrument.

• The secondary winding of...read more

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

• Transformers are used to increase or decrease the voltage in an electrical circuit.

• 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 input voltage source, while the secondary winding is connected to the load.

• Step-up transformers increase ...read more

Circuit breakers are devices that protect electrical circuits from damage caused by overload or short circuit.

• Types of circuit breakers include air circuit breakers, oil circuit breakers, vacuum circuit breakers, and SF6 circuit breakers.

• Air circuit breakers are commonly used in low voltage applications, while oil circuit breakers are used in high voltage applications.

• Vacuum circuit breakers are used in medium voltage applications, and SF6 circuit breakers are used in high vo...read more

GSU calibration error can occur due to zero and span calibration issues.

• GSU calibration error can be caused by incorrect zero calibration, where the sensor does not read zero when there is no input signal.

• GSU calibration error can also be caused by incorrect span calibration, where the sensor does not read the full scale output when a full scale input signal is applied.

• Proper zero and span calibration procedures should be followed to avoid GSU calibration errors.

• Examples of G...read more

Safety management in technical workshops involves identifying and mitigating potential hazards to ensure a safe working environment.

• Conducting regular safety audits and inspections

• Providing appropriate personal protective equipment (PPE) to workers

• Implementing safety protocols and procedures

• Training workers on safe work practices

• Maintaining equipment and machinery to prevent accidents

• Ensuring proper storage and handling of hazardous materials

• Posting safety signs and warnings ...read more

A motor is a device that converts electrical energy into mechanical energy to produce motion.

• Motors are commonly used in various applications such as electric vehicles, industrial machinery, and household appliances.

• They work on the principle of electromagnetic induction, where a current-carrying conductor experiences a force in the presence of a magnetic field.

• Motors can be categorized into different types such as DC motors, AC motors, stepper motors, and servo motors.

• DC mot...read more

Unit of capacitance is Farad (F) and unit of luminous efficiency is lumen per watt (lm/W).

• Unit of capacitance is Farad (F)

• Unit of luminous efficiency is lumen per watt (lm/W)

Capacitors store and release electrical energy. Humming sound in electrical towers can be caused by the vibration of the conductors due to the flow of electricity.

• Capacitors store electrical energy and release it when needed

• Humming sound in electrical towers can be caused by the vibration of the conductors

• The flow of electricity through the conductors can create a magnetic field, leading to the humming sound

VFD stands for Variable Frequency Drive which controls the speed of an AC motor by varying the frequency and voltage of the power supplied to the motor.

• VFD controls the speed of an AC motor by adjusting the frequency and voltage of the power supplied to the motor.

• It helps in saving energy by matching the motor speed to the actual load requirements.

• VFD provides protection to the motor by monitoring parameters like current, voltage, and temperature to prevent overheating or ove...read more

In an electrical circuit, Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance of the conductor.

• Ohm's Law states V = I * R, where V is voltage, I is current, and R is resistance.

• If the voltage in a circuit increases, the current will also increase if the resistance remains constant.

• If the resistance in a circuit increases, the current will decrease if the voltage re...read more

An alternator is an electrical machine that converts mechanical energy into electrical energy.

• An alternator is commonly used in vehicles to charge the battery and power the electrical system.

• It operates on the principle of electromagnetic induction.

• Alternators produce alternating current (AC) which is then converted to direct current (DC) using rectifiers.

• They consist of a rotor, stator, and diodes.

• The rotor is driven by a mechanical source, such as an engine, and rotates wit...read more

To test voltage, use a multimeter set to the appropriate range. To test thermometer readings, use a calibrated thermometer.

• For testing voltage, set the multimeter to the appropriate range (AC or DC) and connect the probes to the circuit being tested.

• For testing thermometer readings, use a calibrated thermometer to compare the temperature readings with the known standard.

• Ensure proper safety precautions are taken while testing voltage to avoid electric shock.

• Calibrate the ther...read more

Managing a site involves coordinating resources, ensuring safety, and overseeing project progress.

• Coordinate with various stakeholders, such as contractors, suppliers, and clients.

• Create a detailed project plan, including timelines, budgets, and resource allocation.

• Ensure compliance with safety regulations and implement necessary precautions.

• Monitor and track project progress, identifying and resolving any issues or delays.

• Maintain effective communication channels to keep all...read more

RBA stands for 'Roller Bearing Assembly'. It is used in rotating machinery to reduce friction and support radial and axial loads.

• RBA is a type of bearing that uses cylindrical rollers instead of balls to reduce friction.

• It is commonly used in heavy-duty applications such as wind turbines, cranes, and mining equipment.

• RBA can support both radial and axial loads, making it ideal for applications where there is both vertical and horizontal movement.

• To use RBA in baring, it shoul...read more

Silica gel is a desiccant commonly used to absorb moisture and prevent the growth of mold and mildew.

• Silica gel is a porous form of silicon dioxide.

• It is often found in small packets or sachets.

• It is used in various industries such as electronics, pharmaceuticals, and food packaging.

• Silica gel can absorb moisture up to 40% of its own weight.

• It is non-toxic and chemically inert.

• Common uses include preserving the freshness of products, protecting electronic devices from moistur...read more

Transformers have two windings, primary and secondary, which are used to transfer electrical energy from one circuit to another.

• Primary winding receives electrical energy from the source

• Secondary winding transfers the electrical energy to the load

• The ratio of turns in the primary and secondary windings determines the voltage transformation

• Transformers can step up or step down voltage levels

• Examples: power transformers, distribution transformers

Handling in construction line involves effective planning, communication, problem-solving, and coordination.

• Develop a detailed project plan and schedule to ensure smooth execution.

• Communicate effectively with team members, contractors, and clients to ensure everyone is on the same page.

• Identify and solve problems promptly to avoid delays and cost overruns.

• Coordinate with different stakeholders, such as architects, engineers, and suppliers, to ensure timely delivery of materia...read more