Theme:

1
Theme

• Power plant CI (IPC) systems
• Tending to Zero Forced Outage
• by
• Internalization of Best Practices

2
Presentation Outline

• 1.Some definitions basics of Pressure, Flow
  Temp. measurement
• 2. Categorization of CI systems based on
  location of application
• 3. Division of power plant CI systems based on
  functionality type of application
• 4.Evolution of CI systems and latest trend in
  technology
• 5.NTPC at a glance and maintenance practices of
  CI systems
• 6. Some case studies

3
Measurement Pressure

• Outline
• Some Definitions
• Pressure Units
• Manometers
• Elastic Pressure Sensors
• Electrical Pressure Sensors
• Pressure Switches
• Snubbers Siphon Tubes

4
Measurement Pressure

• Terminology
• Accuracy Closeness with which an instrument
  reading approaches the true value of the variable
  being measured.
• Precision A measure of reproducibility of the
  measurements i.e. given a fixed value of a
  variable, precision is a measure of the degree
  which successive measurements differ from one
  another.
• Sensitivity The ratio of output signal or
  response of the instrument to a change of input
  or measured variable.
• Resolution The smallest change in measured
  value to which the instrument will respond.
• Error Deviation from the true value of the
  measured variable.

5
Measurement Pressure

• Repeatability refers to the ability of a pressure
  sensor to provide the same output with successive
  applications of the same pressure.
• Hysteresis is a sensor's ability to give the same
  output at a given pressure while increasing and
  decreasing the pressure.

6
Measurement Pressure

• Pressure Definitions
• Definition Force per unit area
• Absolute pressure
• Atmospheric pressure
• Differential pressure
• Gauge pressure
• Importance Pressure measurement is critical
  for safe and optimum operation of processes such
  as steam generation, hydraulic equipment
  operation, air compression, vacuum processing
  etc.

7
Measurement Pressure

• Zero Reference , Gauge, Absolute, Atmospheric
  Pressure
• Any pressure above atmosphere is called gauge
  pressure
• Any pressure below atmosphere is a vacuum
  (negative gauge pressure)
• Absolute pressure (psia) is measured from a
  perfect vacuum
• Differential Pressure has no reference to either
  absolute vacuum or atmospheric pressure

8
Measurement Pressure

• Units
• The SI unit for pressure is the Pascal (Pa)1Pa
  1 Nm-2
• Non-SI unit pound (Lb) per square inch (psi) and
  bar are commonly used
• Pressure is sometimes expressed in
  grams-force/cm2or as kgf/cm2 (KSC)
• 1 atm1.03 ksc14.696 psi760mmHg10000 mmWC
• 101325 Pa
• Standard pressurePressure of normal (standard)
  atmosphere is defined as standard pressure

9
Measurement Pressure

• Pressure Measuring devices
• Manometers
• using water ,mercury and other liquids of known
  density
• For measuring low pressures.
• Mechanical/Elastic Pressure Sensors
• Electrical Pressure Transducers
• For measuring pressure of all ranges for
  telemetering purposes.
• Manometer
• A simple pressure standard
• May be used for gauge, differential, and absolute
  measurements with a suitable reference.
• Useful mainly for lower pressure work because the
  height of the column of mercury will otherwise
  become very high.
• The difference in column heights gives the
  pressure reading

10
Measurement Pressure

• Elastic Pressure Sensors
• The basic pressure sensing elements
• A C-shaped Bourdon tube , B Helical Bourdon
  tube , C flat diaphragm
• D Convoluted diaphragm, E Capsule , F Set of
  bellows

11
Measurement Pressure

• Electrical Pressure Sensors
• Potentiometer Sensor
• Inductive

• Capacitive
• Piezoelectric
• Strain Gauge
• Usually generate output signals in the mV range
  (spans of 100 mV to 250 mV).
• In transmitters, these are amplified to the
  voltage level (1to 5 V) and converted to current
  loops, usually 4-20 mA dc

12
Measurement Pressure

• Pressure Switches
• Applications
• Alarm (Status)
• Shutdown (Hi/Lo Limits)
• Control (ON/OFF)
• A switch is an instrument that
  automatically senses some process variable (such
  as pressure) and provides an on/off signal
  relative to some reference point.

13
Measurement Pressure

• High Pressure In High Temperature
• When high process temperatures are present,
  various methods of isolating the pressure
  instrument from the process are used.
• These include siphons, chemical seals with
  capillary tubing for remote mounting, and
  purging.
• Snubbers its use
• Chemical Seal
• Siphon

14
Measurement Pressure

• Pressure Snubbers
• To filter out pressure spikes, or to average out
  pressure pulses, snubbers are installed between
  the process and the instrument
• Instrument indicates avg pr.
• Snubber Before use
  After use
• when one is interested in the
  measurement of fast, transient pressures (such
  as to initiate safety interlocks on rising
  pressures), snubbers must not be used, as they
  delay the response of the safety system.

15
Measurement Pressure

• Chemical Seal or diaphragm Protector
• Chemical seals are used when media can
  falsify the pressure measurements due to high
  temperature, high viscosity or their property to
  crystallise

16
Measurement Pressure

• Siphon
• A siphon is a coiled tube. This coil
  provides a large cooling surface and the trap
  created prevents the condensate from draining
  away.
• A siphon is required for hot condensing.
  fluids, such as steam, to assure a liquid trap.
• It is used to prevent live steam from
  entering and damaging the device.
• It is used to protect the instrument from
  hydraulic or thermal shocks.
• The two most common forms of siphon tube
  are the 'U' and Pigtail types.

17
Measurement Flow

• Types of flow meters
• Orifice Flow meter
• Vortex flow meter
• Ultrasonics flow meter
• Coriolis Mass Flow meter
• Major issues for selecting flow meters
• Orifice Flow-meters
• 
  Several sensors rely on the pressure drop
  or head occurring as a fluid flows by a
• resistance. The relationship between flow
• rate and pressure difference is determined
• by the Bernoulli equation.

18
Measurement Flow

• Orifice Flow-meters
• An orifice plate is a restriction with an opening
  smaller than the pipe diameter which is inserted
  in the pipe the typical orifice plate has a
  concentric, sharp edged opening.
• Because of the smaller area the fluid velocity
  increases, causing a corresponding decrease in
  pressure.
• The flow rate can be calculated from the measured
  pressure drop across the orifice plate, P1-P3.  
• The orifice plate is the most commonly used flow
  sensor, but it creates a rather large
  non-recoverable pressure due to the turbulence
  around the plate, leading to high energy
  consumption.

19
Measurement Flow

• Venturi Tube
• The change in cross-sectional area in
  the venturi tube causes a pressure change between
  the convergent section and the throat, and the
  flow rate can be determined from this pressure
  drop.  Although more expensive that an orifice
  plate the venturi tube introduces substantially
  lower non-recoverable pressure drops

20
Measurement Flow

• Pitot Tubes
• Pitot tubes were invented by Henri Pitot
  in 1732 to measure the flowing velocity of
  fluids. Basically a differential pressure (dp)
  flow meter, a pitot tube measures two pressures
  the static and the total impact pressure.
• Pitot tubes are used to measure air flow in
  pipes, ducts, stacks, and liquid flow in pipes,
  open channels.
• While accuracy and rangeability are relatively
  low, pitot tubes are simple, reliable,
  inexpensive, and suited for a variety of
  environmental conditions, including extremely
  high temperatures and a wide range of pressures.

21
Measurement Flow

• Pitot Tubes
• A single-port pitot tube can measure the flow
  velocity at only a single point in the
  cross-section of a flowing stream.
• The probe must be inserted to a point in the
  flowing stream where the flow velocity is the
  average of the velocities across the
  cross-section, and its impact port must face
  directly into the fluid flow.

22
Measurement Flow

• Pitot Tubes
• The point velocity of approach (VP) can be
  calculated by taking the square root of the
  difference between the total impact pressure (PT)
  and the static pressure (P) and multiplying that
  by the C/D ratio, where C is a dimensional
  constant and D is density
• The pitot tube measures the static and dynamic
  (or impact) pressures of the fluid at one point
  in the pipe. 
• The flow rate can be determined from the
  difference between the static and dynamic
  pressures which is the velocity head of the fluid
  flow.

23
Measurement Flow

• Vortex Flow-meters
• This measuring principle is based on the fact
  that vortices are formed downstream of an
  obstacle in a fluid flow, e.g. behind a bridge
  pillar.
• This phenomenon is commonly known as the Kármán
  vortex street.

24
Measurement Flow

• Vortex Flow-meters
• This is detected by a sensor, such as
  capacitive sensor and fed to the electronic
  processor as a primary, digitized, linear signal.
• Capacitive sensors with integrated
  temperature measurement can directly register the
  mass flow of saturated steam as well.
• Universally suitable for measuring liquids, gases
  and steam
• Largely unaffected by changes in pressure,
  temperature and viscosity
• High long-term stability (lifetime K factor), no
  zero-point drift
• No moving parts
• Marginal pressure loss

25
Measurement Flow

• Ultrasonic flow-meters
• Swimming against the flow requires more
  power and more time than swimming with the flow.
  Ultrasonic flow measurement is based on this
  elementary transit time difference effect.
• Two sensors mounted on the pipe simultaneously
  send and receive ultrasonic pulses.
• At zero flow, both sensors receive the
  transmitted ultrasonic wave at the same time,
  i.e. without transit time delay.
• When the fluid is in motion, the waves of
  ultrasonic sound do not reach the two sensors at
  the same time.

26
Measurement Flow

• Ultrasonic flow-meters
• This measured "transit time difference" is
  directly proportional to the flow velocity and
  therefore to flow volume.
• By using the absolute transit times both the
  averaged fluid velocity and the speed of sound
  can be calculated.
• Ultrasonic flow meters measure the difference of
  the propagation time (transit time) of ultrasonic
  pulses propagating in (normally an inclination
  angle around 30 to 45 is used) flow direction
  and against the flow direction.
• This time difference is a measure for the
  averaged velocity of the fluid along the path of
  the ultrasonic beam

27
Measurement Flow

• Ultrasonic flow-meters
• Advantages
• With homogeneous fluids, the principle is
  independent of pressure, temperature,
  conductivity and viscosity
• Usable for a wide range of nominal diameters
  Direct meter installation on existing pipes
• Non-invasive measurement
• No pipe constrictions, no pressure losses
• No moving parts. Minimum outlay for maintenance
  and upkeep

28
Measurement Flow

• Coriolis Mass Flow-meters
• If a moving mass is subjected to an oscillation
  perpendicular to its direction of movement,
  Coriolis forces occur depending on the mass flow.
  
• A Coriolis mass flow meter has oscillation
  measuring tubes to precisely achieve this effect.
  
• Coriolis forces are generated when a fluid
  ( mass) flows through these oscillating tubes.
  Sensors at the inlet and outlet ends register the
  resultant phase shift in the tube's oscillation
  geometry.

29
Measurement Flow

• Coriolis Mass Flow-meters
• The processor analyzes this
  information and uses it to compute the rate of
  mass flow.
• Advantage
• This principle is used in a huge range of
  industry sectors, including pharmaceuticals,
  chemicals and petrochemicals, oil and gas, food
  etc.

30
Measurement Flow

• Major issues for selecting flow-meters
• Accuracy
• Repeatability
• Linearity
• Reliability
• Range/Span
• Dynamics(Response time)
• Safety
• Maintenance
• Cost

31
Measurement Temp.

• Measurement Devices
• Thermocouples
• Resistance Thermometers
• Thermistors
• Bimetallic Thermometers
• Acoustic Pyrometers
• Local Instruments

32
Measurement Temp.

• Thermocouple
• IT IS BASED ON SEEBECK EFFECT WHICH
  SAYS THAT WHEN HEAT IS APPLIED TO A JUNCTION OF
  TWO DISSIMILAR METALS AN EMF IS GENERATED WHICH
  CAN BE MEASURED AT THE OTHER JUNCTION
• T/C Connection
• 
  COMPENSATING CABLE
• HOT JUNCTION
• 
  TO DDC
  CARDS
• TERMINAL END
  CJC BOX

33
Measurement Temp.

• Thermocouple
• Types of T/CE,J,K,T,R,S,B
• K (Chromel Alumel Ni-Cr Ni-Al) Type mostly
  used in power plant for low temp. application )
• R (Platinum Platinum-Rhodium) Type Used for
  high temp. application. Highly resistant to
  oxidation corrosion
• Advantages -
  Disadvantages -
• - Low Cost
  - Sensitivity low low
  voltage output
• - No moving parts, less likely to be broken.
  susceptible to noise
• -Wide temperature range.  
  - Accuracy not better than 0.5 C
• -Reasonably short response time.  
  - Requires a known temperature
• - Reasonable repeatability and accuracy.
  reference

34
Measurement Temp.

• RESISTANCE THERMOMETER (RTD)
• THE RESISTANCE OF A CONDUCTOR CHANGES WHEN
  ITS TEMPERATURE IS CHANGED .THIS PROPERTY IS
  UTILISED TO MEASURE THE TEMPERATURE.
• Rt Ro (1ßdT)
• WHERE ß TEMP CO- EFFICIENT OF RESISTANCE dT
  TEMPERATURE DIFFERENCE
• When discussing RTDs, following must be
  considered
• Wiring configuration (2, 3 or 4-wire)
• Self-heating
• Accuracy RTD types
• Stability 1. Platinum
  (Range -200 C to 600 C )
• Repeatability 2. Copper (Range
  -100 C to 100 C )
• Response time 3. Nickel (Range
  -60 C to 180 C )

35
Measurement Temp.

• THERMISTORS
• THERMISTORS ARE GENERALLY COMPOSED
  OF SEMICONDUCTOR MATERIALS.THEY HAVE A NEGATIVE
  COEFFICIENT OF TEMPERATURE SO RESISTANCE
  DECREASES WITH INCREASE IN TEMP.
• Making use of Negative Temperature
  Coefficient characteristics, thermistor and can
  be applied in temperature compensation, inrush
  current limit, precision temp. control (temp.
  coefficient very large compared to RTC T/C)
  etc.
• BIMETALLIC THERMOMETERS
• ALL METALS EXPAND OR CONTRACT WITH TEMPERATURE
• THE TEMPERATURE COEFFICIENT OF EXPANSION IS NOT
  THE SAME FOR ALL METALS AND SO THEIR RATES OF
  EXPANSION AND CONTRACTION ARE DIFFERENT
• USAGE IN PROCESS INDUSTRIES FOR LOCAL
  TEMPERATURE MEASUREMENTS
• OVERLOAD CUTOUT SWITCH IN
  ELECTRICAL APPARATUS

36
Measurement Temp.

• ACOUSTIC PYROMETER
• Acoustic Pyrometer is a non-contact measurement
  device that obtains highly accurate instantaneous
  gas temperature data in any area of the boiler,
  helping improve combustion efficiency.
• For measurement of temperatures across large
  spaces of known distance in a noisy, dirty and
  corrosive environment such as a coal-fired
  utility boiler, or a chemical recovery boiler.
• The Velocity of Sound in a medium is proportional
  to the Temperature.
• LOCAL INDICATION
• LIQUID IN GLASS THERMOMETER
• MERCURY IN STEEL THERMOMETER
• BIMETALLIC THERMOMETER

37
Power Plant CI systems

• 1.Field instruments/ input output instruments
• Various measuring instruments like Transmitters,
  RTD, Thermocouples, Pr. temp. gauges, speed
  vibration pick ups etc. (Analog inputs)
• Various Pr., Temp. limit switches, for
  Interlock , protections feedback of control
  element (Binary inputs)
• Output devices like solenoids, EP converters,
  Positioners etc. for controlling final control
  element
• Final control elements like Power cylinder,
  Pneumatic/ motorized actuators etc.

38
Power Plant CI systems

• 2. Control Systems
• Various control cabinets for acquiring field
  signal (both analog binary inputs), processing
  the signals as per control logic and issuing
  output command to output devices (Binary
  analog).
• Various control desk devices like command
  consoles, Push button modules, indicators,
  recorders, CRTs, PC based Operator Work Stations
  (OWS) etc. for human machine interface for
  monitoring control of the plant
• Power supply system(UPS)/ chargers with battery
  backups to ensure uninterrupted power supply of
  desired quality for the control system

39
Power Plant CI systems

• 3. Analyzers
• The availability, reliability
  efficiency of boiler unit hinge around the close
  control of chemical regimes of working fluid i.e.
  water/steam as well as combustion in the boiler.
  The instruments monitoring the chemical regimes
  and combustion are generally called analytical
  instruments. These instruments fall under three
  category
• Water/ Steam Analyzers
• Gas analyzers
• Smoke monitors
• HIGH PURITY WATER IS ESSENTIAL TO MINIMISE
• SCALING
• CORROSION
• CARRY OVER
• EMBRITTLEMENT

40
Power Plant CI systems

• ANALYZERS AND MEASURMENT LOCATION
• ON LINE gas analyzers for measurement of flue gas
  oxygen, carbon mono-oxides, carbon
  di-oxides, oxides of sulpher nitrogen at
  various location of boiler.
• ON LINE analyzers for measurement of
  conductivity, pH, silica, dissolved oxygen,
  phosphate, hydrazine, chloride, sodium etc. at
  various points in the water steam cycle of
  boiler turbine area (SWAS-steam water
  analysis system).
• ON-LINE opacity monitors for measurement of dust
  concentration in flue gas
• ON LINE analyzers for measurement of
  conductivity, pH, silica, dissolved oxygen etc.
  at various ION exchangers of DM plant .

41
Power Plant CI systems

• TYPICAL VALUES OF CHEMICAL PARAMETERS BEING
  MEASURED (SWAS)

42
Power Plant CI systems

• 4. Laboratory Instruments Setup
• Activities of CI Lab
• CALIBRATION
• REPAIR
• TESTING with proper documentation records
• CALIBRATION
• Pressure switch , Transmitter , Gauge
• Temperature switch , Transmitter , Gauge
• Flow Transmitter
• Level Switch

43
Power Plant CI systems

• 4. Laboratory Instruments Setup
• REPAIR
• 1. ELECTRONIC CARDS
• 3. POWER SUPPLY MODULES
• TESTING
• 1. ELECTRONIC MODULES
• 2. RELAYS
• 3. POWER SUPPLY MODULES

44
Power Plant CI systems

• 4. Laboratory Instruments Setup
• Different standard instruments with traceability
  up to national standard . These insts. include
  Standard Gauges, Multimeters, Resistance boxes,
  mA sources, oscilloscope, signal generator etc.
  for calibration of measuring instruments.
• Dead Weight tester, Comparator, Temperature
  bath, Vacuum pump, manometer, soldering stations
  etc.
• Test benches with standard power supply sockets
  (e.g. 24VDC, 48VDC, 220VDC, 110VAC, 230VAC etc.)
  in each bench depending on requirement.
• Laboratory should be air-conditioned with
  monitoring of temp., humidity and barometric
  pressure. Also, proper provision for handling
  electronic cards (floor mats, ESD protective
  bags/ anti static bags etc.)

45
Power Plant CI systems

• 4. Laboratory Instruments Setup
• Essential Tools/ Infrastructure for Repairing
  testing
• 1. IN-CITCUIT IC TESTER
• 2. ESD WORK STATION
• 3. ULTRASONIC CARD CLEANER
• 4. STORRAGE OSCILLOSCOPE
• 5. LOGIC ANALYSER
• 6. THERMOCOUPLE SIMULATOR
• 7. VIDEO PATTERN GENERATOR
• 8. EPROM PROGRAMMER

46
Power Plant CI systems

• CI systems of Boiler
• FSSS (Furnace safeguard supervisory system)
• Open loop control system (interlock
  protections) of boiler auxiliaries
• Secondary Air Damper control system (SADC)
• Hydrastep for drum level measurement
• Measurements, Protection Control of Coal
  Feeders

47
Power Plant CI systems

• FSSS
• FUNCTIONS OF F.S.S.S
• 1. FURNACE PURGE SUPERVISION
• 2. OIL GUNS ON/OFF CONTROL
• 3. PULVERISERS/FEEDERS ON/OFF CONTROL
• 4. SECONDARY AIR DAMPERS CONTROL
• 5. FLAME SCANNER INTELLIGENCE
• 6. BOILER TRIP PROTECTIONS

48
Power Plant CI systems

• FSSS
• WHY AT ALL A PROTECTIVE SYSTEM IS
  REQUIRED FOR THE BOILER?
• THE BOILERS FURNACE IS CONTINUOUSLY
  FED WITH HIGH CALORIFIC VALUE ATOMISED FUEL WHICH
  IS IN THE PROCESS OF CONTINUOUS BUT CONTROLLED
  COMBUSTION.
• COMBUSTION-THE PROCESS
• COMBUSTION IS A RAPID BURNING OF OXYGEN
  WITH FUEL RESULTING IN RELEASE OF HEAT. AIR IS
  ABOUT 21 OXYGEN AND 78 NITROGEN BY VOLUME. MOST
  FUELS CONTAIN CARBON, HYDROGEN AND SULPHUR. A
  SIMPLIFIED COMBUSTION PROCESS COULD BE
• CARBONOXYGENCARBONDIOXIDE HEAT
• HYDROGENDO WATER VAPOUR HEAT
• SULPHUR DO SULPHURDIOXIDE HEAT
• WHICH MEANS THAT THE FINAL
  DESIRED PRODUCT OF THE PROCESS IS HEAT WHICH WE
  REQUIRE TO BOIL THE WATER

49
Power Plant CI systems

• FSSS
• COMBUSTION-THE PROBLEM WHEN THIS
  CONTROLLED BURNING GOES OUT OF CONTROL DUE TO AN
  IMBALANCE IN THE FUEL/AIR RATIO, THERE IS EITHER
  A FUEL RICH MIXTURE OR A FUEL LEAN MIXTURE. IN
  BOTH CASES THE FLAME QUALITY BECOMES POOR. THERE
  IS A CHANCE OF FUEL ACCUMULATION WHICH CAN LATER
  ON IGNITE SUDDENLY AND CAUSE EXPLOSIONS.
• SO FSSS IS USED FOR SAFE AND ORDERLY
  STARTUP AND SHUTDOWN OF BOILER THROUGH VARIOUS
  INTERLOCKS AND PROTECTIONS
• THE PROTECTIVE SYSTEM IN THE
  BOILER IS DESIGNED BASICALLY TO PREVENT
  OCCURRENCE OF SUCH SITUATIONS BY TAKING ADVANCE
  ACTIONS.

50
Power Plant CI systems

• N.F.P.A Guide line Boiler Protection
• N.F.P.A- National Furnace Protection Association,
  USA
• Deals with protection for various types of
  furnace
• Protection of Pulverized fuel fired boiler is
  governed by Section-85c
• Different categories of protection
• a) Mandatory, b)Mandatory automatically
  generated, c) Optional but alarm has to be there

51
Power Plant CI systems

• BOILER FLAME FLAME SCANNERS
• It looks rather
  static, but in reality the fire energy
  fluctuates rapidly. The Fuel and Oxygen in
  the uncontrolled fire constantly burn as in
  small explosions and then sucks
  new Fuel Oxygen to the flames.
  This process causes the flame
  flicker.
• Flicker frequency for oil
• flame is more than
  that of coal flame.

52
Power Plant CI systems

• INTENSITY RELATIVE TO WAVELENGTH

53
Power Plant CI systems

• FLAME SCANNERS
• -UV Scanners
• -Visible Range Scanners (Safe scan-12)-Used for
  both Oil Coal Flame
• -IR Scanners (UR600 of ABB)
• SAFE FLAME
  SCANNER

54
Power Plant CI systems

• CI systems of Turbine
• ATRS (Automatic Turbine Runup system)
• Turbine Governing System
• Turbovisory Instruments turbine protections
• Interlock, Protection Control of HPBP system
• Open loop control system (interlock
  protections) of turbine auxiliaries
• Interlock protections of Seal Oil Stator
  water system

55
Power Plant CI systems

• CI systems for control MIS
• -Automatic Control System (ACS)
• -DATA Acquisition system(DAS)
• -Distributed Digital Control Monitoring
• and Information System

56
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• PROCESS Process refers to the method of
  changing or refining raw materials to create the
  desired end product. The raw materials may
  undergo physical, chemical, or thermal state
  changes during the Process.
• Process is of Two Types
• A) Continuous and B) Batch
• Continuous Process is one where the change
  of state of Input into Output occurs
  continuously.
• Ex. Power Plant Process, Petroleum
  Industry etc.
• Batch Process is one where a Batch of the
  Product is produced and the Process stops till
  production of next Batch is started.
• Ex. Automobile Production

57
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• PROCESS CONTROL Process control techniques are
  developed over the years to have
• Quality of the end product
• Economy of production
• Ability to cater to emergencies and bring the
  process to safe shutdown.
• CONTROLLED CONDITION The physical quantity or
  condition of a process or machine which is to be
  controlled
• CONTROL SYSTEM An arrangement of elements
  interconnected and interacting in such a way that
  it can maintain some condition of a process or
  machine in a prescribed manner

58
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• OPEN AND CLOSED LOOP CONTROL
• A Closed Loop Control (CLCS) is one
  where a Process Variable is measured, compared to
  a Set Value and action is taken to correct any
  Deviation or Error from Set Value. The continuous
  Measurement of PV and its comparison to Set
  Point closes the Loop.
• An Open Loop Control(OLCS) is one where
  the PV is not compared with Set Value and action
  taken, but action is taken without regard to
  conditions of PV.

59
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• OPEN LOOP CONTROL
• Open Loop Control is accomplished by the
  following means
• Group Control
• Sub-Group Control
• Sub-Loop Control
• Drive Level Control
• Programmable Logic Control(PLC)
• Group Control Start and Stoppage of a Group of
  equipment is accomplished by Group Control(GC).
• Ex. CEP GC, Equipment Cooling GC etc.

60
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• OPEN LOOP CONTROL
• Sub-Group Control Start and Stoppage of
  an equipment with its associated auxiliaries in
  Step-Sequence manner is done by Sub-Group
  Control. Operator intervention is not required in
  Sub-Group Control(SGC).
• Sub-Loop Control Start and Stoppage of
  auxiliaries of an equipment is carried out by
  Sub-Loop Control(SLC)
• Drive Level Control Start and Stop or
  Opening and Closure of a Drive is carried out by
  Drive Control. The Drive logic shall have
  Protection, release ,auto and manual commands and
  these are executed as per pre-determined logic.

61
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• CLCS TERMINOLOGY
• Desired Value or Set Point The value of
  the variable/parameter which needs to be
  controlled at the required condition.
• Process Variable(PV) The present value of
  the Parameter of Process at that particular
  instant. This is sometimes referred as Measured
  Value.
• Error/Deviation It is the Difference
  between Set Point and Process Variable, and can
  be ve or ve. It has three components a)
  Magnitude b) Duration and c) Rate of change.
• Controller A Controller is a device that
  receives data from a Measurement Instrument,
  compares the data with the Set Point and if
  necessary, signals a Control element to take
  Corrective action. This Corrective action ensures
  that the PV shall always be maintained at the Set
  Value.
• The Controller can be a) Electronic, b)
  Pneumatic and c) Hydraulic type.

62
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Controller types Functionally, Controllers can
  be
• a) Continuous and b)
  Step Controllers.
• Depending on the control loop controller
  action can be adjusted as (i) Direct
  acting-Increase of process value increases
  controller output
• (ii) Reverse acting- Increase of process
  value decreases controller output
• Control Element The Control or Correcting
  Element is the part of the Control System that
  acts to physically change the Manipulated
  Variable.
• Ex. Control Valves, Louvers or Dampers,
  Solenoids, Pump Motors etc.

63
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Bump less Transfer The arrangement where the
  transfer from auto to manual mode does not affect
  the process.
• Proportional Control The Proportional (P)
  action responds only to a change in the magnitude
  of Error(e) i.e. controller output changes by an
  amount which is proportional to error.
• Output change of Controller in
  (Error change in )(Gain), where Gain is called
  the Controller gain. The reciprocal of Gain is
  termed as Proportional Band(PB) and is expressed
  in .
• Proportional Band(PB) The change in
  deviation required to cause the output of the
  controller to change from one extreme to the
  other.
• Integral Control In Integral Control, the
  Controller output is a function of the Duration
  of Error(e).

64
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Hence, the Controller output is the time
  Integral of Error and the time set is Integral
  Action Time(IAT) i.e. IAT can be defined as time
  taken for the integral action to change output by
  the same amount as the proportion action .
• Usually, both P and I Controls are
  combined and the Controllers are tuned to
  minimize Error(e) and controller is termed as PI
  controller.
• Derivative Control Derivative or Rate
  Controllers output is Proportional to the rate
  of change of Error(e). The Control action is
  termed as D. The action is to apply an immediate
  response that is equal to the PI action that
  would have occurred some time in the future.

65
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Important Closed Loop Controls in a Thermal Power
  Plant
• a) Furnace Draft Control
• b) Boiler Drum Level Control
• c) HOT well D/A level control
• d) Main Steam Temperature Control
• e) Air and Fuel Flow to Boiler Control
• f) SH RH spray control
• g) Coordinated Master Control(CMC)
• h) Turbine Speed, Pressure and Load Control

66
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Coordinated Master Control
• This is an integrated automatic control of
  unit operation. There is a continuous co
  ordination between boiler and turbine control to
  maintain a balance between steam generation and
  steam consumption.
• Boiler Follow Mode (BFM)
• Turbine Follow Mode (TFM)
• Co-ordinated Master Control (CMC)
• Runback Mode

67
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Boiler Follow Mode (BFM)
• Unit load control from turbine local load set
  point
• Change in turbine load set point will modulate
  turbine CVs
• Boiler master output gets corrected to maintain
  throttle pr dev.
• Boiler control will follow turbine control
• BLI signal as feed forward signal for boiler
  firing rate control
• Result - Boiler acts as throttle pr controller
  where turbine is in load controller mode

68
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Turbine Follow Mode (TFM)
• Unit target load set point goes to boiler master
• Change in BLI will modulate turbine CVs
• Boiler master output gets corrected to maintain
  Unit load dev.
• Turbine control will follow boiler control
• Load deviation as feed orward signal for boiler
  firing rate control
• Result - Boiler acts as load controller where
  turbine is in pressure controller mode

69
Power Plant CI systems

• AUTOMATIC CONTROL SYSTEM POWER PLANT CONTROL
  LOOP
• Coordinated Master Control
• Unit load is set from unit master.
• Unit master demand is limited by unit capability
  , TSE margins and unit max/min load set points.
• Unit target load is derived from unit master
  after the limitations.
• Unit target load is used as feed forward signal
  to the boiler firing rate control.
• Turbine control utilises the unit load as turbine
  load set point after adapting the same by steam
  generation delay.
• In TG throttle pressure is maintained by
  correcting the BMD output depending on the
  throttle pr dev.
• Result Balance is achieved between steam
  generation and steam consumption PROPER
  COORDINATION BETWEEN BOILER CONTROL AND TURBINE
  CONTROL

70
Power Plant CI systems

• DATA ACQUISITION SYSYTEM-DAS
• WHY DAS IS REQUIRED IN THERMAL POWER PLANTS ?
• SAFE RELIABLE OPERATION OF THE UNIT OR
  EQUIPMENTS
• ASSIST CONTROL ROOM OPERATORS BY PROVIDING TIMELY
  ANNUNCIATION OF ALL ABNORMAL CONDITIONS
• PROVIDE DETAILED INFORMATION ON THE PLANT
  PERFORMANCE
• PROVIDE MANAGEMENT WITH ACCURATE RECORDS ON THE
  PAST PLANT PERFORMANCE FOR ANALYSIS

71
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• 3 MAJOR FUNCTIONS OF DAS
• DATA ACQUISITION
• DATA PROCESSING
• DATA REPRESENTATION
• The Major Parts
• Process Control Units ( PCU )
• Computer Interface Unit ( CIU )
• Termination Units ( TU )
• Buffer Terminal Cabinets ( BTC )

72
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• TYPES OF DATA (Input) Analog Digital
• Analog inputs
• 1. Thermocouple Input ( mV )
• K-Type T/C ( Cr-Al ) For temp lt 600 Deg C used
  in Flue Gas path after FSH outlet.
• R-Type T/C ( Pt-Pt-Rh ) For temp gt 600 Deg C
  used in PSH FSH region of FG path.
• 2. RTD Input ( Resistance )
• Pt-100 RTD For Brg. Temp measurement.
• Cu-53 RTD For HT motor Generator Stator
  winding temp. measurement.

73
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• Analog inputs
• 3. 4 20 Ma Input
• Coming from Pr. / Flow Transmitters.
• Coming from Signal Distribution Cards of
  automatic control system
• 4. 0 10
  Volt Input
• Coming from ATRS cabinets
• Used for Turbine Brg. Temp. /Vibration
  measurement.
• DIGITAL INPUTS
• These are coming directly from switches or
  relay contacts of other systems (FSSS, ATRS, ACS
  etc.)

74
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• DIGITAL INPUTS (TYPES)
• LOW RESOLUTION The scanning time of inputs is
  1 second.
• HIGH RESOLUTION The scanning time is 1
  millisecond. These are called Sequence
  Of Events ( SOE ) Inputs.
• PULSE INPUT For calculation of
  Total Coal Flow, Total Air Flow etc.
  

75
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• FUNCTIONS OF DAS
• Alarm Management.
• Production of hardcopy print outs in different
  printers.
• Operator Guidance Messages.
• Graphic Displays of plant sub-systems.
• Trending of analog variables on recorders.
• Sequence Of Events ( SOE ) recording following
  unit / equipment trip conditions.
• Efficiency calculations

76
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• DATA PROCESSING It has the following parts
• COMPUTER PROCESSING UNIT ( CPU )
• BULK ( SOLID STATE ) MEMORY WITH BATTERY BACKUP
• MAGTAPE UNIT
• COMMUNICATION CABINET MODEM
• MOVING HEAD DISC DRIVE
• VIDEO HARD COPIER
• TREND RECORDER
• UNIT CONTROL DESK PROG. ROOM CRT
• PRINTERS

77
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• Features
• REAL TIME VARIABLE CALCULATION
• Summing, Subtraction, Maximum , Minimum,
  Averaging, Hourly Daily integration, rate of
  changes comparison of limits etc.
• ON-LINE DATABASE EDITION
• 1. Assign points to any process parameter
• 2. Scan, Off-scan , Delete , Activate ,
  inactivate a process parameters , calculated
  points when reqd.
• 3. Change the Engg. Unit
• 4. Change the range , alarm limits dead bands
• 5. Change the scan frequency
• 6. Review total analog and digital points
  depending on its quality flag like alarm ,
  channel failure , off-scan etc.

78
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• ALARM MANAGEMENT
• All the analog points which cross their normal
  limits or all the digital points which go into
  their alarm state come on the alarm CRT with
  associated time blink as long as the alarms
  remain unacknowledged.
• Alarm will come in RED colour
• If all the pages are full (normally no. of alarm
  pages alarm per page is predefined) and any new
  alarm comes , then oldest alarm will disappear
  from the alarm page as FIFO basis
• Alarm print out will be available in alarm
  printer

79
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• DATA REPRESENTATION
• Printed outputs of displays /collection of data
  in different formats like
• 1. Copy Screen
• 2 Alarm Print out
• 3. Log Print out
• CRT Displays
• 1. Alarm CRT display
• 2. Utility CRT display

80
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• DATA REPRESENTATION
• TYPES OF TREND LOG PRINOUTS
• TIME ACTIVATED
• EVENT ACTIVATED
• DEMAND LOGS
• SOE PRINTOUT
• TIME ACTIVATED LOG
• Automatic Triggered Logs
• Sample frequency is 1 Hour.(Normally)
• Time of trigger can be specified

81
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• TIME ACTIVATED LOG
• Max. 15 nos. of points can be assigned
• Normally printed in the logging printer in UCB
• Examples
• 1. Shift Log
• 2. Efficiency Log
• 3. Boiler Drum / Tube Metal Temp. Log
• 4. FSH / RH Metal temp. excursion Log
• EVENT ACTIVATED LOG
• Automatic Triggered Logs
• Used for Unit or Equipment Outage Analysis
• Minimum Sample frequency is 10 seconds.

82
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• EVENT ACTIVATED LOG
• Max. 36 points can be assigned in a log
• Logs are triggered by a Trip flag
• Normally printed on Logging Printer in UCB
• Pre Post triggered points can be specified
• Examples
• 1. Post Trip Analysis Log ( PTL )
• 2. TG. Shutdown Analysis Log
• 3. Boiler Startup Log.
• 4. Turbine / Generator Diagnostic Logs

83
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• DEMAND LOG
• Not Automatic Triggered Logs
• Logs can be printed on operators demand
• Sample frequency is generally 1 Hour.
• Logs are printed in Logging Printer in UCB

84
Power Plant CI systems

• DATA ACQUISITION SYSYTEM
• SEQUENCE OF EVENTS ( SOE )
• THE MAIN FEATURES ARE
• Determines First Cause Of Trip
• Determines sequence of events or alarms
• Scanning Time is 1 millisecond.
• It is a Stand Alone System
• Max. 256 nos. of Protection related digital
  points can be assigned
• Automatic Triggered when any point in alarm

85
Power Plant CI systems

• DDCMIS
• WHAT IS DDCMIS ?
• DISTRIBUTED DIGITAL CONTROL MONITORING
  INFORMATION SYSTEM
• Distributed means there is no centralized control
  and control is spread across multiple units
• Digital means processing of process information
  is done in digital form using micro-processor
  based hardware
• MIS interfaces the human with process using
  computers

86
Power Plant CI systems

• DDCMIS
• TECHNOLOGICAL BACKGROUND
• PROGRESS OF INSTRUMENTATION USED TO
  IMPLEMENT AUTOMATIC PROCESS CONTROL
• LOCAL PNEUMATIC CONTROLLERS
• MINIATURIZED AND CENTRALIZED PNEUMATIC
  CONTROLLERS AT CONTROL PANELS AND CONSOLES
• SOLID-STATE CONTROLLERS
• COMPUTERISED CONTROLS
• DISTRIBUTED MICROPROCESSOR BASED CONTROL

87
Power Plant CI systems

• DDCMIS
• Components

MAN MACHINE INTERFACE PROCESS INFORMATION SYSTEM
DATA COMMUNICATION SYSTEM (DATA HIGH WAY)
CONTROL SYSTEM
88
Power Plant CI systems

• DDCMIS
• MAN-MACHINE INTERFACE AND PLANT INFORMATION
  SYSTEM (MMIPS)
• LATEST STATE-OF-THE-ART WORKSTATIONS AND SERVERS
  BASED ON OPEN-ARCHITECTURE AND INDUSTRY STANDARD
  HARDWARE AND SOFTWARE TO ENSURE BETTER
  CONNECTIVITY.
• e.g. HARDWARE FROM COMPAQ/DIGITAL, HP, SUN
  MICRO-SYSTEM OR OTHER MAJOR SUPPLIERS (LESS
  DEPENDENCE ON THE CI SYSTEM SUPPLIER IN THE LONG
  RUN)
• OPERATING SYSTEM WINDOWS-NT, OPEN-VMS OR UNIX.
• PROVISION OF LVS
• CONNECTION TO OTHER SYSTEM THROUGH STATIONWIDE
  WAN

89
Power Plant CI systems

• DDCMIS
• MMIPIS FUNCTIONALITIES
• VARIOUS PLANT EQUIPMENT OPERATION
• OPERATOR INFORMATIONS THROUGH VARIOUS DISPLAYS
• ALARMS, LOGS, HISTORICAL AND LONG TERM STORAGE.
• PERFORMANCE AND OTHER CALCULATIONS

90
Power Plant CI systems

• DDCMIS
• DATA COMMUNICATION SYSTEM
• LOCAL SYSTEM BUS It is just lines on the
  backplane of control panel to which all the
  modules are connected directly. It serves as
  communication medium between the modules.
• INTRAPLANT BUS(IPB) It is a coaxial cable which
  runs through all the panels of control system and
  interconnects them.
• LOCAL AREA NETWORK(LAN) It is a network of
  computers which are connected to a single point
  (HUB).
• FOR ALL BUSES REDUNDANCY IS PRESENT

91
Power Plant CI systems

• DDCMIS
• CONTROL SYSTEM
• FUNCTIONAL DIVISION
• SG-CI SYSTEM
• TG-CI SYSTEM
• BOP-CI SYSTEM
• HARDWARE COMPONENTS
• POWER SUPPLY
• CONTROL PANEL
• ELECTRONIC MODULES

92
Power Plant CI systems

• DDCMIS

93
Power Plant CI systems

• DDCMIS
• SG-CI SYSTEM
• BURNER MANAGEMENT SYSTEM (BMS)
• SOOT BLOWER CONTROL SYSTEM (SBC)
• SECONDARY AIR DAMPER CONTROL SYSTEM (SADC)
• AUXILIARY PRDS CONTROLS (APRDS)
• TG-CI SYSTEM
• ELECTRONIC TURBINE PROTECTION (ETP)
• AUTOMATIC TURBINE RUN-UP SYSTEM (ATRS)
• AUTOMATIC TURBINE TESTING SYSTEM (ATT)
• ELECTRO- HYDRAULIC TURBINE CONTROL SYSTEM (EHTC)
• TURBINE STRESS CONTROL SYSTEM (TSC)
• LP BYPASS SYSTEM (LPBP)
• HP BYPASS SYSTEM(HPBP)
• GLAND STEAM PRESSURE CONTROL
• GENERATOR AUXILIARY MONITORING PANEL (GAMP)

94
Power Plant CI systems

• DDCMIS
• BOP-CI SYSTEM
• CONSISTS OF OPEN LOOP CONTROL SYSTEM
  (OLCS) AND CLOSED LOOP CONTROL SYSTEM (CLCS)
• OLCS - THE SEQUENCE CONTROL, INTERLOCK OF ALL THE
  PLANT SYSTEMS WHICH ARE NOT COVERED IN THE SG-CI
  AND TG-CI. THIS INCLUDES MAJOR AUXILIARIES LIKE
  FD/ID/PA FANS, AIR-PREHEATER, BFP/CEP/CWP/ BCWP ,
  DMCWP/CLCWP AND ELECTRICAL BREAKERS.
• CLCS - THE MODULATING CONTROL FOR VARIOUS
  IMPORTANT PLANT PARAMETERS, LIKE FW FLOW (DRUM
  LEVEL), FURNACE DRAFT, COMBUSTION CONTROL (FUEL
  FLOW AND AIR FLOW), PA HDR PRESSURE CONTROL,
  DEAERATOR/HOTWELL/HEATER LEVEL CONTROLS ETC.

95
Power Plant CI systems

• DDCMIS
• WHY DDCMIS ?
• VERY HIGH FLEXIBILITY FOR MODIFICATION IN
  CONTROL STRATEGY
• VERY HIGH SELF-DIAGNOSTIC
• VERY LOW DRIFT (ONLY IN I/O CARDS) , HENCE NO
  NEED OF FREQUENT RE-CALIBRATION
• MUCH HIGHER RELIABILITY (BASED ON MTBF)
• BETTER LONG TERM SUPPORT DUE TO CHANGING
  TECHNOLOGY
• MUCH BETTER OPERATOR INTERFACE

96
Power Plant CI systems

• DDCMIS
• SALIENT FEATURES OF DDCMIS
• INTEGRATED PLANT CONTROL FOR SG, TG AND BALANCE
  OF PLANT CONTROL
• IT MAY BE REMEMBERED THAT
  HISTORICALLY THE TERM DDCMIS USED REFER TO THE
  SO-CALLED BOP-CI . THE SG-CI, i.e. FSSS etc.
  TG-CI i.e. ATRS, TURBINE PROTECTION etc.
  ORIGINALLY WERE NOT CONSIDERED UNDER DDCMIS OR
  DCS AS PER MANY SUPPLIERS. ONLY RECENTLY THE TYPE
  OF SYSTEMS FOR ALL THE SYSTEMS HAVE BECOME
  SIMILAR (WITH SOME DIFFERENCE WHICH WILL BE
  DISCUSSED LATER), WE TEND TO CONSIDER THESE
  SYSTEMS UNDER DDCMIS.

97
Power Plant CI systems

• DDCMIS
• SALIENT FEATURES OF DDCMIS
• INTEGRATED PLANT OPERATION THROUGH FULLY
  INTERCHANGEABLE OPERTAOR WORK STATIONS (OWS) FOR
  SG, TG AND BALANCE OF PLANT
• PROVISION OF EXTENSIVE SELF-DIAGNOSTICS
• USE OF LARGE VIDEO SCREENS FOR PROJECTIONS OF
  VARIOUS PLANT MIMICS ETC.
• PROVISION OF FAULT ALARM ANALYSIS TO GUIDE THE
  OPERATOR TO THE MOST LIKELY EVENT
• PROVISION OF ADEQUATE RELIABILITY AND
  AVAILABILITY WITH PROPER REDUNDANCY IN SENSOR,
  I/O AND CONTROLLER LEVELS.

98
Power Plant CI systems

• Global National Power Scenario
• Global
• Global electricity consumption 69 higher in 2020
  than 2003
• 80 of energy provided from thermal sources
• Emerging trend from Thermal to Hydel and
  Renewable Energy sources
• Indian
• Total installed capacity only 1362 MW in 1947
• Per Capita consumption 631 units (2005-06) only
  with installed capacity of 1,77,000 MW
• GDP growth of 8, power growth required 10
• To add 1,00,000MW capacity by 2017
• Liberalizations of the sector

99
Power Plant CI systems

• NTPC at a glance
• Installed Capacity 34199 MW
• Target 75000MW by 2017
• Performance
• Annual Availability 91.62
• Annual PLF 88.29
• 11 stations among top 20 in the country

100
NTPC Practices to achieve goal

• KEY THRUST AREAS
• Zero Human Error
• Implementation of trip committee recommendations
  judiciously / rigorously
• Identification of trip committee recommendations
  of other stations
• which are relevant and implement them
• Implementation of operation memorandum wherever
  applicable
• Dissemination of information about best practices
  followed across
• NTPC and other Power Stations
• Providing proper environment for CI equipment to
  reduce probability of
• card and equipment failure

101
CI Trip Trend
102
2009-10 FORCED OUTAGE DISTRIBUTION (COAL)
103
INFERENCE 2009-10 CI OUTAGE ANALYSIS

• Major factors contributing to CI outage in
  2009-10
• Control System related failure
• 2. Field Device Failure
• 3. Soft ware/Card Failure
• 4. Power Supply/Relay failure
• 5. Human error

104
BEST PRACTICES COMPILED/ADOPTED IN NTPC CI

• All unit protections are provided with 2/3
  logic and audio visual alarm is provided on 1/3
  to operator on actuation of any one sensor
  wherever possible with proper approval.
• Use of headless RTD in tripping circuit of
  ID/PA/FD fans BFPs.
• Resistance mapping of critical solenoids
  including cable during overhauls and monitoring
  trend to identify any defects.
• Marking of trip related devices and Junction
  Boxes marked in RED color.
• Regular calibration of all important instruments
  which have a bearing on unit safety, reliability
  and efficiency. Instruments are calibrated
  against standard instruments with traceability to
  NABL.

105
 
BEST PRACTICES COMPILED/ADOPTED IN NTPC CI

• For handling of electrostatic sensitive
  electronic hardware, electrostatic bags, wrist
  straps and other ESD handling devices are
  employed in control panels and lab. All
  Laboratories are provided with ESD proof
  workstations.
• Disable removable drives of servers and
  workstations.
• Single source responsibility for software backup
  of DCS and storage in fire proof cabinets in two
  different locations.
• Detailed work instruction are prepared and
  followed for working on all trip related devices.

106
BEST PRACTICES COMPILED/ADOPTED IN NTPC CI

• A single source responsibility is fixed for the
  generation and maintenance of system passwords so
  as to maintain system security
• Internal quality inspection for critical checks
  during overhauls to ensure quality in overhaul
  works
• Near miss situations are monitored and analyzed.
  The learning from this area used to formulate
  strategies to avoid spurious outages.
• All power supply voltages are monitored with a
  fixed periodicity and maintained within /- 10 of
  the rated value.

107
BEST PRACTICES COMPILED/ADOPTED IN NTPC CI

• Fuses used in UPS and protection circuits are
  replaced with new fuses of same rating and type
  during every overhaul
• Earth voltages in control panels are monitored on
  a predetermined frequency and the values are
  recorded for trending
• All bus terminators are checked during every
  overhaul for ensuring integrity of bus
  communication in DDCMIS systems
• Load testing of power supplies for critical
  applications and replacement of power supply
  modules or electrolytic capacitor and power
  transistors used in power supply if found
  deteriorated.

108
 
Other important actions taken for forced outage
reduction

• Rerouting of control power cables in hot zones
• Panel power supply monitoring in regular
  intervals.
• CER/UCB temperature and humidity monitoring
  online. Insisting for performance of the A/C
  system
• Checking and tightening power supply cables
  during overhaul
• Ensuring healthiness of cabinet cooling fans.

109
Other important actions taken for forced outage
reduction

• Panel cooling fans supply segregation from system
  supply with MCB / fuse.
• Cleaning of air filters on panels periodically
• Servo valve replacement/ servicing in hydraulic
  drives.
• Individual fuse protection in 220VDC MFT for
  HOTV, LOTV, HORV, Scanner emergency air damper
  solenoids

110
Looking from WBPDCL Santaldih Perspective
KEY THRUST AREAS

• Commissioning of non commissioned systems
• Soot blowing Steam Pr. Control valve
• Status- Actuator damaged while
  commissioning. BHEL has placed PO on OEM M/s
  MIL for procurement of damaged parts
• b) Commissioning of SWAS analyzers
• Status-Procurement of Reagents for reagent
  based measurement (i.e. Silica etc.) is in
  process.
• Suggested to take up with OEM (Forbes
  Marshall) through BHEL for commissioning of
  electrode based measurements (i.e. conductivity
  etc.)

111
Looking from WBPDCL Santaldih Perspective

• c) Electromatic Relief Valve (ERV)
• Status- Solenoid Installed and cabling done
• d) APH Rotor stop alarm
• Status- Issue pending with BHEL for
  longtime. Alternative scheme through DDCMIS
  suggested by fixing proximity switch on APH
  rotor shaft at support brg. end.
• APH fire detection alarm
• Status- Issue pending with BHEL for
  longtime. Alternative scheme by measuring APH
  metal temp. using thermocouples in Air Gas path
  may be thought of.

112
Looking from WBPDCL Santaldih Perspective
f) Commissioning/testing of Back up (Back up of
MAX DNA system work stations)Push Button console
for unit control Suggested to test the
operation of various push buttons at the time of
Start up/ Shutdown of unit jointly with
operation.
2. Rectification of long pending problems a)
Problem of SADC systems Status Operation of
some of the dampers erratic and needed frequent
adjustment due to unreliable performance of
actuator/positioner Suggested to procure 04 nos.
actuator with positioner of reputed manufacturer
for replacement in one elevation on trial basis
113
Looking from WBPDCL Santaldih Perspective

• b) High PA flow to Mills
• In auto PA flow of all mills are about 30
  more than characteristic flow. PA flow curve for
  sliding set point may be set as per mill design.
• Also provision of manual set point may be
  explored to cater poor coal quality
• 3. Setting up of CI Lab with requisite
  facilities
• 4.Enhancing reliability of Field Instruments
• Proper glanding/ sealing of field instruments,
  control valves, routing dressing of cables,
  ensuring cleanliness closure of all LIEs etc.

114
Looking from WBPDCL Santaldih Perspective

• Replacement of unreliable instruments by quality
  instruments
• c) Marking of protection related JBs to avoid
  human error
• Regular walk down check in various areas to
  ensure the healthiness of field instruments.

5. Sealing Cable dressing in MAX DNA panels
during unit Shutdown 6. Disabling various ports
for removable drives of MAX DNA work stations
for system reliability 7. Installation of ON
Line printers of MAX DNA system for daily LOGs.
Daily LOGs are essential for analysis of
different plant parameters by OE dept.
115
Looking from WBPDCL Santaldih Perspective
8. Cleanliness of NETWORK ROOM EWS room to
be ensured. Monitoring of Temp. Humidity of
CER, UCB , NETWORK EWS rooms.

9.Implementation of regular cleaning schedule
preventive mtc. Schedule for Boiler, Turbine
and common systems 10.Prepartion of detail job
list for unit overhauling 11. Review of spares
status and timely action for procurement for
breakdown(corrective), preventive and overhauling
maintenance.
116
THANK YOU