Ea of cw, ct & cond. system

A PRACTICAL APPROACH
to
ENERGY AUDIT IN CW, CT & CONDENSER SYSTEM
in
THERMAL POWER STATIONS

D.Pawan Kumar
And
R.Virendra

1.0 BACKGROUND
Cooling Water Circuit and System performance,
holds the key in maintaining optimum vacuum in a
thermal or a GT combined cycle plant. In current
times, there is an increasing demand on power
plant professionals, to address concurrently,
complex tasks like ; Cooling water Consumption
optimization, Achieving vacuum conditions and
Optimizing power consumption in CW pumps and
CT fans, despite plant side variations, like
frequency, cooling water quality, availability, load
variations, O & M demands, etc. While it is a
challenge, experiences show that with the level of
infrastructure and information available at most
sites, it should be possible to conduct a reasonably
detailed and functional energy audit, deploying in-
house resources, to bring out improvement options.

2.0 AUDIT FOCUS
CW / CT system and condenser vacuum being focal
points for energy audit study, the various
improvement issues addressed in the CW audit
include ;

2.1 Condenser Related
 Cleanliness of tube surfaces
 Tube leakages
 High inlet water temperature
 CW flow adequacy

2.2 CW Pump Related
 Efficiency of CW pumps
 Fore bay level inadequacy
 Mains frequency related
 CW flow tapping for other purposes
 Parallel operations and effects

2.3 Cooling Tower Related
 Approach, range of cooling towers
 L/G ratio of cooling towers
 Tuning scope in cooling towers, with seasonal
variations with regard to water load, CT fan
blade angle, etc.
 Maintenance of fills
 Quality of Cooling Water and COC improvement
 CT fan blade material such as FRP/GRP, etc.

2.4 Overall Optimization related such as ;

 Optimize CW pump operations with
respect to thermal load
 Optimizing L/G ratios during various
seasons
 Optimize CW pump efficiency through
need based maintenance, retrofit,
replacement options.
 Optimize condenser operations through
O & M

3.0 Based on experiences at various
plants

The following steps are envisaged as
illustrative help tools for the CW / CT
audit teams in conduct of energy audit in
thermal power plants and GT based
combined cycle plants.

3.1 Scope of Audit
The scope of audit pertains to Energy Audit of Cooling Water System
including Cooling Towers & Condenser is made into systems as given below :

 CW System : Audit for water consumption
 Cooling Tower : Audit for CT effectiveness
 Condenser : Audit for condenser heat load, CW flow & Vacuum

The energy audit on above system will be carried out to determine main
features such as :

1. Consumption of circulating water flow
2. Performance of CW pumps w.r.t. CW flow
3. CT effectiveness and L/G ratio
4. Performance of condenser w.r.t. heat load and vacuum and CW pressure
drop across condenser.
5. Comparison of measured performance with reference to designed / rated
values.
6. Recommendations based on the performance of the above system.

3.2 Methodology for Energy Audit

1. Discussion with operation, Electrical Maintenance,
Mechanical Maintenance, C&I and Chemistry
2. Selection of equipments and instruments for power
measurement for CW pumps & CT fans
3. Data collection based on power measurement, DBT / WBT
measurement for cooling performance, UCB data collection
for heat load calculation
4. Analysis of data
5. Calculation of performance to determine key indicators for
assessing the performance of various systems.

Contd..

3.3 Preparations for Audit

 Selection of appropriate time for conducting audit.
 Selection of units for audit.
 Selection of equipments & instruments for
measurement.
 Calibration of instruments for pressure & temperature
measurement in DAS.
 Assistance from O & M personnel.
 Design / rated parameters from technical operating
manuals, equipments name plates, etc.

3.4 DESIGN DATA COLLECTION
3.4.1 DESIGN DATA – CONDENSER
S. DESCRIPTION DATA
NO
1. Tube Material
2. Tube Outside dia (mm)
3. Tube Thickness (mm)
4. Total Number of Tubes
5. Tube Length (Meters)
6. No. of Plugged Tubes
7. No. of Passes
8. Design Surface Area (SQM)

3.4.2 DESIGN DATA – STEAM SIDE
9. Back Pressure (kg / sq. cm)
10. Condenser Duty

3.4.3 DESIGN DATA – WATER SIDE
S. DESCRIPTION DATA
NO
11. Cooling Water Flow
12. CW Inlet Temperature
13. CW Outlet Temperature
14. Design Water Velocity
15. CW Pressure Drop
16. CW Source
17. Design Cleanliness Factor

3.4.4 DESIGN DATA – GENERATOR
S. DESCRIPTION DATA
NO
18. Design Heat Rate kCal / kWh at ….. MW
19. Gross Power Generated MW

3.4.5 WATER CHEMISTRY - DESIGN VALUES

S. DESCRIPTION DATA
NO
1. PH at 250C
2. Conductivity
3. T.D.S
4. Total hardness
5. Calcium Hardness
6. Magnesium Hardness
7. P-Alkalinity
8. M-alkalinity
9. Chloride
10. Sulphate
11. Cycle of Concentration
12. L.S.I

3.5 Equipments & Measurements
The following instruments are typically used for measuring various
parameters in the context of energy audit of CW, CT & Condenser
performance.

Intake air DBT & WBT at each cell (ground level) Psychrometer
CW inlet temperature common) (risers or CT top) Hg in glass thermometer
CW outlet temperature (common) (fills bottom) Hg in glass thermometer
CW sump / basin temperature (overall) - Do -
UCB Data : MW load, frequency, condenser, inlet / DAS
outlet temperature, condenser vacuum, extraction
steam flow from heaters, etc.
CW pump elect. Data : Motor amps, volts, power Measurement by power
factor, kilo watt analyser
CT pump house fore-bay level Physically measured
CW pump readings for TDH
CT fans : Amps Tong tester
CT transformer – Amp., Volts, PF, kW Power analyser
Lab analysis data of CW (inlet), OAC and makeup Lab water analysis
water

3.6 AUDIT DATA COLLECTION

The following parameters are typically chosen for spot
observations.
1. UCB Parameters : MW load, frequency, main steam flow, extraction
steam flow for various heaters, LPT exhaust steam flow, steam
temperatures & pressures, condenser vacuum etc., for calculation of
condenser heat load & CW flow.
2. ELECTRICAL Parameters : Measurement of voltage, power factor
& kW for CW pumps, CT transformer & CT fans.
3. MECHANICAL Parameters CW PUMPS : Measuring data for TDH
of CW pumps and Fore bay level.
4. CHEMICAL / THERMAL Parameters : Measurement of DBT /
WBT of air at cooling tower, CT basin water temperature, CW quality
I.e., TDS & COC for CT performance & CW system water consumption.

SAMPLE DATA SHEET – 1
S. Parameters Unit Design Unit Data
No Value
.
1. Unit Load MW 210.0 211.0
2. Frequency Hz 50.0 51.2
3. M.S. Temperature 0
C 535.0 530.0
4. M.S. Flow T/Hr. 651.3 730.0
5. HRH Pr. Kg/Sq. Cm 24.8 24.5
6. HRH Temperature 0
C 535.0 535.0
7. CRH Pr. Kg/sq. Cm 28.8 30.3
8. CRH Temperature 0
C 328.0 324.0
9. Feed Water Flow T/Hr. 651.3 689.0
10 F.W. Temperature at Inlet of
HPH 5 0
C 167.0 164.0
HPH 6 0
C 182.0 185.0
HPH 7 0
C 225.0 220.0
11. F.W. temperature at outlet of
HPH 5 0
C 182.0 185.0
HPH 6 0
C 225.0 220.0
HPH 7 0
C 248.0 257.1
Contd..

SAMPLE DATA SHEET – 1 Contd..

No Value
.
12. Drip Temperature from
HPH 5 0
C 177.0 171.8
HPH 6 0
C 192.0 202.6
HPH 7 0
C 235.0 236.1
13. Ex. Steam temperature at inlet to
HPH 5 0
C 440.0 455.9
HPH 6 0
C 328.0 323.7
HPH 7 0
C 378.0 415.5
14. Ex. Steam pressure at inlet to
HPH 5 Kg / sq. cm 12.7 12.3
HPH 6 Kg / sq. cm 28.8 28.9
HPH 7 Kg / sq. cm 42.2 40.7
15. Condensate temperature at inlet of
LPH 1 0
C 44.0 58.0
LPH 2 0
C 66.0 59.0
KPH 3 0
C 105.0 97.0
LPH 4 0
C 127.0 119.0
Contd..

SAMPLE DATA SHEET – 1 Contd…

S.N Parameters Unit Design Value Unit Data
o
16. Condensate temperature at outlet of
LPH 1 0
C 63.0 59.0
LPH 2 0
C 105.0 97.0
KPH 3 0
C 127.0 119.0
LPH 4 0
C 159.0 156.0
17. Drip temperature from
LPH 1 0
C 66.0 59.0
LPH 2 0
C 102.0 105.0
KPH 3 0
C 115.0 117.0
LPH 4 0
C 150.0 158.0
18. Ex. Steam Temperature at inlet to
LPH 1 0
C 95.0 97.0
LPH 2 0
C 177.0 169.0
KPH 3 0
C 252.0 261.0
LPH 4 0
C 352.0 388.0
19. Ex. Steam pressure at inlet to
LPH 1 0
C 0.3 0.2
LPH 2 0
C 1.5 1.8
KPH 3 0
C 3.0 3.3
0

SAMPLE DATA SHEET – 1 Contd…
S.N Parameters Unit Design Value Unit Data
o
20. CW inlet temperature 0
C 30.0 32.5
Pass – A 0
C 30.0 32.6
Pass – B 0
C 30.0 32.4
21. CW outlet temperature 0
C 38.4 44.2
Pass – A 0
C 38.4 44.2
Pass – B 0
C 38.4 44.1
22. LPT exhaust temperature 0
C 43.2 50.4
Pass – A 0
C 43.2 50.8
Pass – B 0
C 43.2 50.0
23. CEP suction temperature 0
C 43.0 48.9
24. Condenser vacuum (as per DAS) Kg/Sq Cm. 0.911 0.871
25. Con. Vac (Kinetometer) Cm Hg. 66.95 64.60
Con. Vac (Kinetometer) Kg/Sq. Cm 0.911 0.879
Con. Vac (as per LPT exhaust) Kg/Sq. Cm 0.911 0.872
26. Air / Steam mixture temp. (Ejec-A) 0
C 46.0
Air / Steam mixture temp. (Ejec-B) 0
C 42.0
27. Ejector steam pressure Kg/Sq. Cm 19.19
28. CW pressure at condenser inlet Kg/Sq. Cm N/A
29. CW pressure at condenser outlet Kg/Sq. Cm N/A
CW pressure drop across cond. Tubes Kg/Sq. Cm 0.370 --

CT FAN DUTY
Item Ref. Units Design Fan- Fan Fan- Fan- Fan- Fan- Fan- Fan Fan Sum
A - B C D E F G -H -I
Voltage V 415 418 418 418 418 418 418 418 418 418
(measured)

Current A 113 90 88 98 0 85 88 90 85 90 714
(measured)

Motor 0.897 0.897 0.897 0.897 0.897 0.897 0.897 0.897 0.897

power
factor
Motor 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9
efficiency
(Ref.)
Fan input kW 67 52.60 51.43 57.27 49.67 51.43 52.60 49.67 52.60 52.16

power

CT fan air Kg / 2654 2448 2430 2519 2402 2430 2448 2402 2448 19528

flow × 1000 hr

CHEMICAL DATA FOR CIRCULATING WATER
Month TDS Na COC pH Turbidity
ppm ppm NTU
March 150 9.8 1.5 8.3 22
April 174 11.5 1.64 8.31 8.5
May 161 11.5 1.55 8.48 13.0

S.N Quality of Water Effect of Quality
o
1. Low COC = 1.6 to 1.8 Less corrosive effect
2. High COC > 2.0 Scale deposition increases
3. Acidic pH Very corrosive
4. pH > 8.5 [A ]. Copper pick increases
Material of Condenser tube = Cu 95 % Ni 5 %
[B ] Chlorine effect reduces
5. COC V. Low = < 1.3 No scale deposition (because less TDS in CW system); but
metal pick increases fast
6. Turbidity MU water turbidity = 20 NTU (make-up water)
7. TDS Values Raw MU Water TDS = 100 / 110 PPM

FORMULAE USED FOR CALCULATIONS - A

1. Condenser heat load calculation :
The following data is required for heat load calculation :

a) LPT exhaust flow
b) Enthalpy of exhaust steam
c) Enthalpy of condensate

a) LPT exhaust flow

= [Main steam flow – Extraction steam flow – Aux. Steam
flow – D/A steam flow – ESV leak-off – Seals leakage]

Contd..

FORMULAE USED FOR CALCULATIONS - A

Extraction steam flow is calculated by heat balance i.e.,

Extraction Steam Flow = Feed Water flow (FW I/L temp. - FW O/L temp.
Enthalpy of exhaust steam −Drip temperatur e
 
 

Condenser heat load
= [ LPT exh. Steam enthalpy – Condensate enthalpy] × Exhaust Steam flow rate

CW flow can be calculated by heat balance

CW Flow = Condenser heat load (k Cal / Hr.)
CW temperatur e rise (0 C)

FORMULAE USED FOR CALCULATIONS - B
2. CW flow calculation as per power measurement :

Power input to motor = 3 V I × PF kW
1000

Power input to pump = Motor efficiency × Power input to motor
LKW = Pump efficiency × Motor efficiency × Power input to motor

CW pump discharge flow = LkW × 3600 M3 / Hr.
TDH× 9.81

Actual CW flow thro’ condenser = less than 100 % of CW
discharge flow as

 Part of CW flow is often used for cooling purposes in turbine
side boiler side, ash slurry, etc.

FORMULAE USED FOR CALCULATION - C
3. CT fan air flow calculation :

Power input to motor = 3 V I × PF kW
1000

Power input to fans = Motor efficiency × Power input to motor kW

3

 Fan input power  
Fan air flow actual =   × Fan rated CMH
Rated fan input power 
 

Air flow per fan

G/L Ratio = Air flow per cell (by wt.)
CW flow per cell (by wt.)

Evaporation losses = CT Flow × CT Range M3/Hr.
675

Makeup water = Evaporation loss M3/Hr.
(COC- 1)

Contd..

FORMULAE USED FOR CALCULATION - D

4. COC is defined as the ratio of total dissolved solids in
basin water to TDS in makeup water.

Water Consn. = (Evaporation Losses + Makeup water) M3/Hr.

CT Range = CW temp. at CT inlet – CW temp. at bottom fills

CT approach = CW temp. at CT outlet – WBT at ground level

 Range 
% CT effectiven ess = 



× 100
 Range + Approach
 

 CWT Inlet - CWT Outlet 
=   × 100 %

 CWT Inlet - WBT 


SAMPLE CALCULATION SHEET FOR
CONDENSER HEAT LOAD CALCULATION
Steam parameters at salient points :

No Value
.
1. Enthalpy of LPT exhaust steam kCal/kg 585.7 619.3
2. Enthalpy of condenser at CEP kCal/kg 43.2 48.9
suction
3. Enthalpy of ex. Steam at HPH 5 I/L kCal/kg 799.2 807.4
6. Enthalpy of ex. Steam at LPH 1 I/L kCal/kg 615.9 640.1

Contd.

SAMPLE CALCULATION SHEET FOR
CONDENSER HEAT LOAD CALCULATION
Steam parameters at salient points :
S. Parameters Unit Design Value Unit Data
No.
1. Extraction steam flow at HPH 5 T/hr. 16.4 22.8
4. Extraction steam flow at LPH 1 T/hr. 16.6 0.8
8. Auxiliary steam flow T/hr. 17.0 17.0
9. HPT seal leakage T/hr. 12.0 12.0
10. HPT ESV leak off T/hr. 2.0 2.0
11. Ext. to deaerator T/hr. 4.0 4.0
12. LPT exhaust flow (calculated) T/hr. 436.7 501.1
13. Av. CW temperature rise 0
C 8.4 11.7
14. Condenser heat load kCal/kg 542.5 570.4
15. Condenser heat load × 1000 kCal/kg 236910 285831
16. CW flow (CMH) CW Flow = (Heat load / T/hr. 28203.5 24534.8
CW Temperature difference)

SAMPLE CW PUMP DUTY ASSESSMENT
Total diff. Head calculation :

S. Item Reference Unit Design Unit
No. Value Data
1. Fore bay level MSL 279.4

2. Fore bay to floor mWC 4.25

3. Bowl loss (Reference) mWC 0.20

4. Height of pressure gauge mWC 1.33

5. Discharge pressure mWC 21.8 – 22.00
22.6
6. Velocity head @ 1.89 m/s mWC 0.18

7. Total differential head mWC 27.96

SAMPLE FLOW BALANCE OF CW PUMP BY MOTOR
a) LOADING
Power measurement by power analyser (Accuracy – Class-I (0.1 %)
b) CW flow calculation based on power measurement
S. Item Reference Unit Design Unit Data
No. Value Pump-A Pump-B

1. Voltage (measured) V 6600 6681 6502
2. Current (measured) A 205 173.98 175.43
3. Power factor (measured) - 0.85 0.6418 0.675
4. Power input to motor kW 2000 1292 1334
5. Power input to pump kW 1221 1260
(@ 94.5% motor efficiency)
6. Average pump input power kW 1241
7. LKW (@ 87 % pump efficiency) 2 × 1130 2159
8. Total CW discharge flow CMH 32350 28332
9. Cooling water for Aux. (15 %) CMH 4850 4250
10. CW flow through condenser CMH 27500 24082
11. CW taken for HP/LP pumps CMH 410 570
12. CW going back to CT CMH 30000 27479
13. CW fans in service CMH 8 8
14. CW flow per cell CMH 3750 3435

SAMPLE CT FAN DUTY ASSESSMENT
Power Measurement by Power Analyser Accuracy Class-I (0.1 %)

No. Value
1. Voltage (measured) V 6600 6509

2. Current (measured) A 45.86

3. Motor power factor -- 0.8969

4. Motor efficiency (Ref.) -- 0.9

5. CT Xmer input power kW 603 417.33

6. Ct fan motor input power kW 67 52.16

7. CT fan flow per tower × 1000 Kg/hr 21229 19530

8. Air flow per cell × 1000 Kg/hr 2654 2441

SAMPLE CT PERFORMANCE
ASSESSMENT
S. Design Unit
No. Item Reference Unit Value Data

1. Water inlet temperature to CT 0
C 43 45

2. Water outlet temperature from 0
C 33 31.5
CT
3. Wet Bulb temperature @ CT 0
C 28.4 24.5
bottom
4. Dry bulb temperature ambient 0
C -- 32

SAMPLE CT SYSTEM KEY INDICATORS

No. Value
1. CT range 0
C 10 13.5
2. CT approach 0
C 4.6 7
3. CT effectiveness 0.685 0.659
4. Water / Air ratio (L/G Ratio) 1.41 1.41
5. Air / Water Ratio (G/L Ratio) 0.71 0.71
6. Evaporation losses CMH 444 550
7. TDS PPM 174 174
8. C.O.C. 2.50 1.64
9. Makeup water CMH 296 859
10. Water consumption CMH 741 1408
11. % water consumption % 2.29 4.97

SAMPLE OVERALL SYSTEM KEY INDICATORS
No. Value
1. Unit load MW 210 211
2. Frequency Hz 50.0 51.2
3. M.S. flow T/hr 651.3 730
4. F.W. flow T/hr 651.3 689
5. Total C.W. flow T/hr 32350 24535
6. C.W. flow thru condenser T/hr 27500 24535
7. Average CW temperature rise 0
C 8.4 11.7
8. Condenser heat load kCal/hr 236910 285831
× 1000
9. Terminal temperature difference 0
C 4.8 6.2
10. LMTD 0
C 8.30 11.04
11. Condenser vacuum Kg/sq.cm 0.911 0.871
12. CW pump pressure drop Meter 3.70 Not
(across condenser) Measurabl
e

ILLUSTRATIVE COMPARISON : CONDENSER
VACUUM AND CW FLOW CHARACTERISTICS
Exhaust
Design Value Actual Steam Actual CW Actual Condenser Hood Steam
Flow to Flow to Condense Vacuum Tempera-
Condenser Condenser r Heat ture
Load
Case T / Hr. T / Hr. kCal/hr T / Hr. 0
C

1. Reference 436.7 28203 236910 0.91 43.2
× 1000

2. Reference 440 27500 0.91 44

3. Reference 480 27500 0.91 45

4. Reference 480 25000 0.9 46

5. Reference 500 25000 0.9 46.1

ILLUSTRATIVE COMPARISON :
CW PUMP PERFORMANCE

No. Value Data
1. Average CW pump motor input kW 1335 1313

2. Average CW pump LKW kW 1130 1079.5

3. CW discharge flow CMH 32350 28332
(16175 CMH each Pump)

4. CW flow thro’ condenser CMH 27500 24082

5. CW flow per cell CMH 3750 3445

6. CT fans on line Nos. 8 8

CT FAN PERFORMANCE

No. Value Data
1. Fan input power kW kW 67 52.17

2. CT fan air flow per tower Kg/hr × 21229 19530
1000
3. CT fan air flow per cell Kg/hr × 2654 2441
1000

4. CW flow per cell Kg/hr × 3750 3445
1000
5. Water/Air ratio (L/G ratio) 1.41 1.41

Dry air density Kg/M 3 1.0555
CT fans in operation No 8
(for design performance)

COOLING TOWER PERFORMANCE
DESIGN DATA

HP KW CW FLOW 30,000 CMH

FAN BHP 76.4 57.0
Hot Water Temp. 109.4 43 C
MOTOR HP 90 67.1 F

Cold Water Temp. 91.4 F 33 F

Fan air flow 21229 kg/hr × 1000 Wet Bulb Temp. 83.1 F 28.4 C

CT fans in 8 Nos. 22 F 12.2 C
operation

CT air flow / 2654 kg/hr × 1000 18 F 10 C
cell

14 F 7.8 C

Contd..

DESIGN DATA

Units Unit
Item Reference Data
CT Range 0
C 13.5

Wet bulb temperature 0
C 24.5
(measured)
76.1 F
Cold water temperature 0
C
31.5
(measured)
Cold water temperature 0
C 32.5
(design)


CW FLOW (M 3 / Hr)

S. Item Reference Design Unit
No. Value Data

A. By process parameters 28203 24535

B. By CW pump motor 27500 24082
loading
C. By LMTD calculation 28728 24000

SAMPLE SCAN OF CW PUMPS –
ENERGY AUDIT OBSERVATIONS

Eqpt. kW Drawn Flow Pressure (kg/cm2) Pumps (mmWc) for Fans Liquid kW Combined S.C.E Unit
Ref. of Air kW Efficiency (%) (kWh/Ton) Motor
Kw TPH Suction* Discharge Differential Loadin Gen. Freq.
g% (MW) (Hz)

Design Actual Design Actual Desi Actu Design Actual Desi Actual Design Actual Design Actual Design Actual
gn al gn

CWP – 1377 1021 15000 13295 0 0 2.5 1.90 2.5 1.90 1021 688.3 74.18 67.43 0.092 0.0768 74.24 189.6 47.91
1
CWP – 1377 1014 15000 13274 0 0 2.5 1.90 2.5 1.90 1021 687.2 74.18 67.76 0.092 0.0764 73.78 186.2 47.85
2
CWP – 1377 1018 15000 13422 0 0 2.5 1.90 2.5 1.90 1021 694.9 74.18 68.23 0.092 0.0759 74.07 191.6 48.36
3

CWP – 1377 1078 15000 13310 0 0 2.5 1.75 2.5 1.75 1021 634.7 74.18 58.89 0.092 0.0810 78.39 193.9 48.20
4

CWP – 1377 983 15000 13159 0 0 2.5 1.85 2.5 1.85 1021 663.4 74.18 67.50 0.092 0.0747 71.47 194.5 47.81
5

CWP – 1377 1104 15000 13197 0 0 2.5 1.80 2.5 1.80 1021 647.3 74.18 68.64 0.092 0.0838 80.28 194.1 47.90
6

CWP – 1377 1143 15000 13183 0 0 2.5 1.95 2.5 1.95 1021 700.5 74.18 61.31 0.092 0.0867 83.09 194.7 47.84
7

CONCLUSIONS
The audit conclusions are site specific and situation
specific. The menu of recommendations substantiated
adequately are most likely to include ;
 Timely descaling of condensers
 Ensuring adequacy of CW flow through condensers
 Improving operational energy efficiency of CW pumps by
maintenance or retrofit or replacement options
 Tuning of CT operations for achieving best CT range, L/G
ratio, approach for given loading, ambient conditions.
 Water quality improvements and design COC
improvements.
 Debottlenecking of any O & M constraints
 Fill replacement/replenishment in cooling towers
 Improvements in instrumentation and MIS for enabling
continuous efforts by O & M and O & E teams.

Ea of cw, ct & cond. system

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