TPM Consultants Interview Questions and Answers

Power factor is a measure of how effectively electrical power is being used in a circuit.

• Power factor is the ratio of real power (in watts) to apparent power (in volt-amperes).

• It indicates the efficiency of electrical power consumption in a circuit.

• A power factor of 1 means all the power is being used effectively, while a power factor less than 1 indicates wastage of power.

• Inductive loads like motors and transformers have a lagging power factor, while capacitive loads have a ...read more

Devices used for power factor improvement include capacitors, synchronous condensers, and static VAR compensators.

• Capacitors are commonly used to improve power factor by storing and releasing electrical energy as needed.

• Synchronous condensers are rotating machines that generate or absorb reactive power to improve power factor.

• Static VAR compensators are solid-state devices that provide reactive power compensation to improve power factor.

• Other devices such as power factor corr...read more

There are three types of induction motors: squirrel cage, wound rotor, and double squirrel cage.

• Squirrel cage induction motors are the most common type and have a simple and robust design.

• Wound rotor induction motors have external resistors connected to the rotor windings, allowing for variable speed control.

• Double squirrel cage induction motors have two sets of rotor windings, providing high starting torque and improved efficiency.

• The principle of operation for all induction...read more

Circuit breaker is a device that automatically interrupts an electric circuit to protect against overcurrents. Isolator is a manually operated switch used for isolating a circuit.

• Circuit breaker is an automatic device, while isolator is manually operated.

• Circuit breaker protects against overcurrents, while isolator is used for isolating a circuit.

• Circuit breaker can be reset after tripping, while isolator cannot be reset.

• Circuit breaker is commonly used in electrical distribu...read more

Preparing a Single Line Diagram (SLD) for an 11kV substation.

• Identify the components of the substation, such as transformers, circuit breakers, and switchgear.

• Determine the electrical connections and interconnections between the components.

• Represent the components and connections using standardized symbols and line diagrams.

• Include relevant information like ratings, voltages, and protective devices.

• Ensure the SLD follows industry standards and regulations.

• Review and revise th...read more

VCB stands for Vacuum Circuit Breaker.

• VCB is an electrical switch that uses vacuum as the arc quenching medium.

• It is used to protect electrical circuits from overloads and short circuits.

• VCBs are commonly used in medium voltage applications.

• They offer advantages such as compact size, high reliability, and low maintenance.

• Example: A VCB may be installed in a distribution panel to protect a building's electrical system.

CT stands for Current Transformer. It is used to measure and monitor electrical currents in power systems.

• CTs are used to step down high currents to a level that can be safely measured by instruments.

• They provide isolation and protection to the measuring instruments from high voltage currents.

• CTs are commonly used in electrical distribution systems, power plants, and industrial applications.

• They are essential for accurate metering, monitoring, and protection of electrical sys...read more