Larsen & Toubro Limited Electrical Supervisor Interview Questions and Answers for Experienced

The major parts in a power transformer include the core, windings, insulation, cooling system, and tap changer.

• Core: Provides a path for magnetic flux and is usually made of laminated steel sheets.

• Windings: Consist of primary and secondary coils that transfer electrical energy.

• Insulation: Prevents electrical leakage and ensures safety.

• Cooling System: Keeps the transformer within operating temperature limits, commonly u...read more

I want to switch electrical circuits and devices.

• Switching electrical circuits to control the flow of electricity.

• Switching electrical devices on or off.

• Switching between different power sources.

• Switching between different modes or settings of electrical equipment.

• Switching between different electrical connections or configurations.

SAP procedure for UPS vendor is a process for managing vendor data in the SAP system.

• The SAP procedure for UPS vendor involves creating and maintaining vendor master data in the system.

• It includes defining vendor attributes such as payment terms, delivery schedules, and contact information.

• The procedure also involves creating purchase orders and managing invoices from the vendor.

• Examples of UPS vendors include APC, Eat

The maintenance procedure of DG involves regular checks and servicing to ensure optimal performance.

• Regularly check oil and coolant levels

• Inspect air filters and replace if necessary

• Clean and inspect spark plugs

• Check battery and charging system

• Perform load bank testing

• Schedule routine maintenance with a qualified technician

• Keep a maintenance log for record keeping

ATS scheme stands for Automatic Transfer Switch scheme used in power systems.

• ATS scheme is used to transfer power supply from one source to another in case of power failure.

• It is commonly used in backup power systems to ensure uninterrupted power supply.

• ATS scheme can be implemented using mechanical or electronic switches.

• It is important to ensure proper coordination between the ATS and protective devices to avoid any ...read more

Address the issue calmly and professionally, listen to their perspective and try to find a solution together.

• Remain calm and avoid getting defensive

• Listen to their perspective and try to understand their point of view

• Communicate clearly and respectfully

• Try to find a solution together

• If necessary, involve a mediator or supervisor

Transformer PM involves regular maintenance and inspection to ensure optimal performance.

• Perform regular visual inspections to check for signs of wear and tear

• Test insulation resistance to ensure it meets standards

• Check oil levels and perform oil analysis to detect any contaminants

• Inspect and tighten connections

• Perform load and temperature tests

• Schedule maintenance based on manufacturer recommendations

• Examples of maint...read more

Transformers are protected by various methods to prevent damage from faults and overloads.

• Overcurrent protection using fuses or circuit breakers

• Thermal protection using temperature sensors and alarms

• Buchholz relay protection for detecting internal faults

• Differential protection for detecting external faults

• Ground fault protection using ground fault relays

• Lightning arrestors for protection against lightning strikes

• Oil le...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

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 gro...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 freshne...read more

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 e...read more

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-t...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 ...read more

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 conn...read more