10+ MASS AV Tech Interview Questions and Answers

The input voltage of 3 phase transformers is typically 480 volts, while the output voltage can vary depending on the application.

• Input voltage of 3 phase transformers is usually 480 volts

• Output voltage can vary based on the application

• Common output voltages include 208V, 240V, and 480V

There are several types of circuit breakers including thermal-magnetic, magnetic, and hydraulic-magnetic. They are used to protect electrical circuits from overloads and short circuits.

• Types of circuit breakers include thermal-magnetic, magnetic, and hydraulic-magnetic

• Thermal-magnetic circuit breakers use a bimetallic strip to respond to overloads

• Magnetic circuit breakers use a solenoid to respond to overloads

• Hydraulic-magnetic circuit breakers use a hydraulic delay to respon...read more

Precautions for working in electrical works include wearing appropriate personal protective equipment, de-energizing circuits before working on them, and following proper lockout/tagout procedures.

• Always wear appropriate personal protective equipment such as insulated gloves, safety glasses, and non-conductive footwear.

• De-energize circuits before working on them to prevent electrical shocks or burns.

• Follow proper lockout/tagout procedures to ensure equipment is safely turned ...read more

Oil transformers use oil as a cooling and insulating medium, while dry type transformers use air or solid insulation materials.

• Oil transformers use oil as a cooling and insulating medium, while dry type transformers use air or solid insulation materials.

• Oil transformers are typically used in high-power applications due to better heat dissipation capabilities.

• Dry type transformers are more environmentally friendly as they do not contain oil, reducing the risk of oil leaks or s...read more

The input voltage of 3 phase transformers is typically 480 volts in industrial settings.

• Input voltage of 3 phase transformers is commonly 480 volts in industrial applications

• Other common input voltages for 3 phase transformers include 208 volts and 240 volts

• Input voltage may vary depending on the specific application and transformer design

There are three input phase wires in 3 phase transformers.

• Three input phase wires are required for 3 phase transformers.

• Each phase wire carries a different phase of the electrical current.

• Examples: R, Y, B phases in a 3 phase system.

LT panel stands for Low Tension panel which is used for distributing power at low voltage levels. HT panel stands for High Tension panel which is used for distributing power at high voltage levels.

• LT panel distributes power at low voltage levels, typically up to 415V.

• HT panel distributes power at high voltage levels, typically above 415V.

• LT panels are commonly used in residential and commercial buildings.

• HT panels are used in industries and power plants for heavy machinery.

• Bo...read more

PAC stands for Programmable Automation Controller, used in industrial automation for controlling processes and machinery.

• PAC is a type of industrial automation controller that combines the features of a PLC (Programmable Logic Controller) with those of a PC (Personal Computer).

• PACs are used in various industries such as manufacturing, automotive, and food processing for controlling processes and machinery.

• PACs offer advanced programming capabilities, high-speed processing, an...read more

UPS stands for Uninterruptible Power Supply, used to provide backup power during electrical outages.

• Provides backup power during electrical outages

• Protects electronic devices from power surges and fluctuations

• Ensures continuous operation of critical systems

• Commonly used for computers, servers, and other sensitive equipment

VCB stands for Vacuum Circuit Breaker, used for electrical protection by interrupting the current flow in case of a fault.

• VCB is used in high voltage electrical systems to protect equipment and personnel from damage or injury.

• It works by creating a vacuum between the contacts to extinguish the arc when the circuit is broken.

• VCBs are more reliable and require less maintenance compared to traditional circuit breakers.

• Examples of VCB manufacturers include Siemens, ABB, and Schne...read more

There are many different parts in a transformer, including coils, cores, windings, bushings, tap changers, and cooling systems.

• Coils

• Cores

• Windings

• Bushings

• Tap changers

• Cooling systems

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

• Transformers consist of two coils of wire, known as the primary and secondary coils.

• They work on the principle of electromagnetic induction, where a changing current in the primary coil induces a voltage in the secondary coil.

• Transformers are used to step up or step down voltage levels in electrical systems.

• Examples of transformers include power t...read more

SMPS stands for Switched Mode Power Supply, a type of power supply that uses switching devices to convert electrical power efficiently.

• SMPS is more efficient than traditional linear power supplies.

• It uses high-frequency switching to regulate the output voltage.

• Commonly used in electronic devices like computers, TVs, and LED lights.

• Helps reduce energy consumption and heat generation compared to linear power supplies.

The main panel is the central control unit that distributes electricity throughout a building.

• The main panel is typically located in a utility room or basement.

• It contains circuit breakers or fuses to protect the electrical system from overloads.

• The main panel is where the main power feed enters the building and is distributed to various circuits.

• It is important for a maintenance technician to know how to safely work with the main panel to troubleshoot electrical issues.

A DG generator, also known as a diesel generator, is a type of generator that uses diesel fuel to generate electricity.

• DG stands for diesel generator

• Commonly used as a backup power source in case of power outages

• Often used in industrial settings, hospitals, data centers, and residential buildings

• Requires regular maintenance and fuel refills to ensure proper functioning

AC stands for alternating current, which periodically changes direction, while DC stands for direct current, which flows in one direction.

• AC is commonly used in household appliances and power distribution systems.

• DC is commonly used in batteries and electronic devices.

• AC changes direction periodically, while DC flows in one direction constantly.

• AC voltage can be easily converted using transformers, while DC voltage requires more complex conversion methods.

CT and PT are abbreviations for Current Transformer and Potential Transformer, used in electrical systems for measuring current and voltage.

• CT is used to measure current in electrical systems

• PT is used to measure voltage in electrical systems

• CT and PT are commonly used in power distribution systems

• CT and PT help in stepping down current and voltage for measurement purposes