nlc report

8/13/2019 NLC Report

1/13


2/13

NEYVELI LIGNITE CORPORATION LIMITED

(Biggest Open-Cast Mechanised Lignite Mines in India)

NEYVELI LIGNITE CORPORATION LIMTED


3/13

The main core activity of NLC is Lignite Excavation and power generation using lignite excavated.

NLC is having lignite mining units named as Mine I, Mine II, Mine IA and Barsingsar Mine. Also Raw

Lignite is being sold to small scale industries to use it as fuel in their production activities.

MINES CAPACITY

MINE I 10.5 MT / A

MINE I A 3 MT / A

MINE II 15.0 MT / A

BARSINGSAR MINE 2.1 MT / A

NLC is generating power in its Thermal Power Station I, Thermal Power Station -II and in

Thermal Power Station I Expansion.

All the southern states are beneficiaries of this power generation project.

NLC is started generating power in Barsingsar Power Station in Rajasthan also.

THERMAL UNITS CAPACITY

TPSI (3x100 + 6x50) 600 MW

TPSII (3x210 + 4x210) 1470 MW

TPS - I EXPANSION (2x210) 420 MW

BARSINGSAR TPS (2x125) 250 MW

MINEII


4/13

History:

In February, 1978 Government of India sanctioned the Second Lignite Mine of capacity 4.7 MT of

lignite per annum and in February `83, Government of India sanctioned the expansion of Second Mine

capacity from 4.7 Million Tonnes to 10.5 Million Tonnes. Unlike Mine-I, Mine-II had to face problems in

the excavation of sticky clayey soil during initial stage. The method of mining and equipment used are

similar to that of Mine-I. The seam is the same as of Mine-I and is contiguous to it. The lignite seam in

Mine-II was first exposed in September 1984 and the excavation of lignite commenced in March, 1985.

GOI sanctioned the expansion of Mine-II from 10.5 MTPA to 15.0 MTPA of lignite in October 2004 with a

cost of Rs. 2295.93 crore. Mine-II Expansion project was completed on 12th March 2010. The lignite

excavated from Mine-II meets the fuel requirements of Thermal Power Station-II and Thermal PowerStationII Expansion under implementation.

Present:

Mine-II has a lignite capacity of 15 Million Tones per Annum. The earth above the lignite named

as overburdenis removed in different phases of excavation viz

1. New Surface bench,

2. Surface bench,

3. Top bench,

4. Middle bench and

5. Bottom bench.

The excavation of ligniteis carried out in the Lignite bench.

GROUND WATER CONTROL


5/13

The water encountered due to deep excavation is pumped out. A department called GROUND

WATER CONTROL carries out this work. The Earth and Lignite excavated are transported to surface

using Conveyors.

Specialised Mining Equipments (SME)

1400 LBucket Wheel Excavator (conventional Type) : 4 nos

1400 LBucket Wheel Excavator (Bridge Type) : 3 nos

700 LBucket Wheel Excavator (conventional Type) : 6 nos

20000T/hr Spreader with Tripper : 3nos

11000T/hr Spreader with Tripper : 2nos

6000T/hr Stacker : 1nos

2800T/hr Reclamier : 2nos

Conveyors

2400mm width, 1250KW Motor with 6.6 K.V

2000mm width, 630KW Motor with 3.3K.V

Description

Bucket Wheel Excavator

Bucket-wheel excavators (BWEs)are heavy equipment used for continuous overburden removal

in surface mining applications. They use their cutting wheels to strip away a section of earth (the


6/13

working block) dictated by the size of the excavator. The primary function of BWEs is to act as a

continuous digging machine in large-scale open pit mining operations. What sets BWEs apart from other

large-scale mining equipment, such as bucket chain excavators, is their use of a large wheel consisting

of a continuous pattern of buckets used to scoop material as the wheel turns.

750KW with 3.3KV Bucket wheel Motors are used here.

Conveyor Belts

A Conveyor belt(or belt conveyor) consists of two or more pulleys, with a continuous loop of

material - the conveyor belt - that rotates about them. One or both of the pulleys are powered, moving

the belt and the material on the belt forward. The powered pulley is called the drive pulley while the

unpowered pulley is called the idler. There are two main industrial classes of belt conveyors; Those in

general material handling such as those moving boxes along inside a factory and bulk material

handling such as those used to transport industrial and agricultural materials, such as grain, coal, ores,

etc. generally in outdoor locations.

Spreader


7/13

Spreadersin mining are heavy equipment used in surface mining and mechanical

engineering/civil engineering. The primary function of a spreader is to act as a continuous spreading

machine in large-scale open pit mining operations. The purpose of the spreader is to receive

overburden from the haulage conveyor from the sorting area and dump it in an orderly and efficient

manner.

Types of Cables

Landline Cables (Black) Cross-sectional Area: 185 , 95 sq.mm

Trailing Cables (Pink) Cross-sectional Area: 185 , 95 , 50 , 35 sq.mm


8/13

MINE-II SUB STATION

POWER SUPPLY.

For electrical power supply requirement of all the equipment for the above said activities is fed

from a 335 MVA, 230/11 KVsub station located at the pivotal point that is centre of mines.

SOURCE OF SUPPLY

The above sub station is fed from the Thermal Power station-II, through 230KV, 250MVAtower

line feeders called MF3 & MF4

CRITICAL ROLE OF 335MVA, 230/11 KV SUB STATION

This sub station caters to the entire needs of the Mine-II project. The 230 KV received is

converted into 11 KVsupply using 12 power transformers. The 11 KV switch yard has been provided

with 120 numbers outlets for connecting the mines loads. There is a control room manned round the

clock with engineers and technicians to monitor the Sub Station.


9/13

Substation Equipments.

Transformers

30 MVA -------------7Nos (3 Main + 4 Expansion)

25 MVA -------------5Nos (Main)

25 MVA TRANSFORMER

KVA - 20000 / 25000

Volts at no load HV 230000

LV 11550

Ampere HV 50.3 / 62.76

LV 1000 / 1250

Phases HV/LV 3/3

Frequency HZ 50

Type of cooling ONAN / ONAF

30 MVA TRANSFORMER

KVA 24000 / 30000

Volts at no load HV 230000

LV 11550

Ampere HV 60.25 / 75.3

LV 1200 / 1500

Phase HV/LV 3/3

Frequency HZ 50

Type of cooling ONAN / ONAF

Circuitbreakers.

A device capable of making and breaking an electric circuit under normal and abnormal

conditions such as short circuits. It can operate automatically and clear fault current safely and quickly.


10/13

Isolator (Disconnecting Switch):

A switching device, which can be opened or closed only under no current condition. It provides

Isolation of a circuit for the purpose of maintenance.

Earthing Switch:

It is a switch that connects a conductor to the earth so as to discharge the charges on the

conductor to the earth. Earthing switches are generally installed on the frames of the isolators.

Relay:

It is an automatic device that closes its contacts when the actuating quantity/quantities reach a

certain predetermined magnitude/phase.

Current Transformer (CT).

The current ratio of current transformer is generally high (e.g. 500 A/5A and volt-ampere

capacity is relatively low (e.g. 50 VA) as compared with that of the power transformers.

Voltage Transformer (VT)

The volt-ampere capacity of a potential transformer is low (e.g.) 100 VA) and the voltage ratio is

relatively high (e.g. 230 KV. / 110V). The protective relays are connected in the secondary circuits of CTs

and VTs.

Lightning Arrester (Surge Arrester)

The equipment connected between the conductor and ground, to discharge the excessive

voltages to earth.

Distribution of 11 KV Supply

From Substation to Machines & Conveyors, The 11 KV supply comes through Landline Cables

terminating with Pillor Boxes, Couplers and Distribution Kiosk.

All the Excavators and Spreaders get supply through Trailing cableswhich are flexible in nature.

Classification of Systems in Machines

11 KV, H.T. System

6.6 / 3.3 KV H.T. System

415V L.T. System

230V Lighting System

110V Control System

24 V Hand Lamps


11/13


12/13


13/13

Electricity is a good Servant, but a bad Master

nlc report

Documents