L&T Defence Service Engineer Interview Questions and Answers

Three-phase supply consists of three alternating currents, while single-phase supply has only one alternating current.

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

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

• Three-phase supply provides more power and is more efficient than single-phase supply.

• Three-phase supply requires three conductors, while single-phase supply requir...read more

Current rating is not written on electrical appliances to avoid confusion and liability.

• Current rating may vary depending on the location and voltage of the appliance.

• Manufacturers may not want to be liable for incorrect usage of the appliance.

• Current rating can be found in the user manual or on the packaging.

• Some appliances may have a range of current ratings depending on the mode of operation.

• Regulations may not requ...read more

A capacitor stores electrical energy and releases it when needed.

• Capacitors are used in electronic circuits to filter out noise and stabilize voltage.

• They can also be used to store energy in flash cameras and defibrillators.

• Capacitors come in different types and sizes, with varying capacitance and voltage ratings.

• They are made of two conductive plates separated by a dielectric material.

• The capacitance of a capacitor de...read more

New fan regulators are more energy-efficient and have additional features compared to old ones.

• Old fan regulators use resistors to control the speed of the fan, while new ones use electronic circuits.

• New fan regulators have additional features such as remote control, timer, and speed settings.

• Old fan regulators are less energy-efficient and can cause the fan to make noise or vibrate.

• New fan regulators are more reliable...read more

No, UPS and inverter are not interchangeable.

• UPS is designed to provide backup power for a short duration, while an inverter is designed to provide continuous power.

• UPS typically has a built-in battery, while an inverter requires an external battery.

• UPS is commonly used for computers and other electronic devices, while inverters are used for larger appliances like refrigerators and air conditioners.

MCB stands for Miniature Circuit Breaker, a device used to protect electrical circuits from overloads and short circuits.

• MCB is a type of circuit breaker that automatically switches off electrical circuits during abnormal conditions.

• It is commonly used in residential and commercial buildings to protect electrical appliances and wiring.

• MCBs are available in different current ratings and trip characteristics to suit diff...read more

MCBs are more reliable and safer than fuses.

• MCBs can be reset and reused, while fuses need to be replaced after every trip

• MCBs have a faster response time than fuses, which can prevent damage to equipment

• MCBs have better overload protection than fuses

• MCBs are more convenient to use as they do not require replacement every time they trip

• MCBs are safer as they do not release harmful gases or debris when they trip

Relay and contactor are electrical switches that control the flow of electricity in a circuit.

• Relays are used to switch smaller currents in a circuit, while contactors are used to switch larger currents.

• Relays are often used in control circuits to turn on or off devices, while contactors are used in power circuits to control motors and other high-power loads.

• Both relay and contactor have an electromagnetic coil that, w...read more