A Presentation on Vocational Training at NSPCL,BHILAI

Presented By:

Contents

• Introduction • Basic Layout• Coal Handling Plant• Demineralization Plant• Boiler Section• Alternator & Turbine• Cooling Towers• Switch Yard & Control Room

Introduction

• NSPCL (NTPC-SAIL Power Co. Private Limited)• Joint Venture started at March 2002.• NSPCL,Bhilai commissioned 2X250 MW coal fired

Bhilai Expansion power plant.• Generating voltage is 11.5KV which is further

stepped up to 33KV.• Other branches are situated at Rourkela & Durgapur.• All these are CAPTIVE power plant.• All these are Coal based Thermal Power Plant.

Basic Layout of the Coal Handling Plant

Demineralization Plant

Boiler Section

Air Pre-heater

• It is a device used in steam boilers to transfer heat from the flue gases to the combustion air before the air enters the furnace.

• Also known as air heater, air-heating system but it is kept at a place near by where the air enters in to the boiler.

• The purpose of the air pre-heater is to recover the heat from the flue gas from the boiler to improve boiler efficiency by burning warm air which increases combustion efficiency, and reducing useful heat lost from the flue.

Super Heater

• A device which removes last traces of moisture.

• It helps in reduction in requirement of steam quantity.

• steam being dry reduces the mechanical resistance of turbine.

• No corrosion at the turbine blades.

Cooling Towers

Remove heat from the water discharged from the condenser so that the water can be discharged to the river or re circulated and reused.

• Air can be circulated in the cooling towers through natural draft and mechanical draft.

ALTERNATORS

Switch Yard Components

• Power Transformers• Circuit Breaker• Relays• Current Transformer• Potential Transformer• Isolator(line & bus)• Interconnecting Transformer• Bus Coupler• Insulator• Lightning Arrestors

Bus Coupler• Two different bus sections of two different power

transformers are connected by means of a bus coupler. • The bus coupler becomes useful when one of the power

transformers fails or a fault occurs in either of the bus sections.

Insulator• The overhead line conductors should be supported on the poles

or towers in such a way that currents from conductors do not flow to earth through supports i.e., line conductors must be properly insulated from supports. This is achieved by securing line conductors to supports with the help of INSULATORS.

• The insulators provide necessary insulation between line conductors and supports and thus prevent any leakage current from conductors to earth.

Lightning Arrester• A lightning arrester is a device used on electrical power systems and

telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning.

• The typical lightning arrester has a high-voltage terminal and a ground terminal.

• When a lightning surge (or switching surge, which is very similar) travels along the power line to the arrester , the current from the surge is

diverted through the arrestor, in most cases to earth.

Circuit Breaker & Relays• A circuit breaker is an automatically operated electrical switch designed to

protect an electrical current from damage caused by overload or short circuit.

• Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow.

• The circuit breaker works along with the relays which give a tripping signal in case of any irregularity or the faults.

• The circuit breaker then opens to open the circuit such that other instruments of the system can be protected.

ISOLATORS: (GOD)- GROUP OPERATED DISCONNECTOR:

• It is used to make sure that an electrical circuit can be completely de-energised for service or maintenance.

• It allows isolation of apparatus such as circuit breakers and transformers, and transmission lines, for maintenance.

• GOD’s are provided to facilitate isolation of breakers supplying power to various feeders. In 220kv Switchyard, they are designed as 29A, 29B, 29C & 29E as follows

29 A – main bus side GOD. 29 B - Equipment side GOD. 29 C - Transfer bus side GOD. 29 E - Earth GOD.

Current & Voltage Transformer• Current or voltage instrument transformers are necessary

for isolating the protection, control and measurement equipment from the high voltages of a power system, and for supplying the equipment with the appropriate values of current and voltage - generally these are 1A or 5Α for the current coils, and 120 V for the voltage coils.

SWITCH YARD- Single Line Diagram