control & operation philosophy of ac

16.01.13 R-1 2nd Sub SC SC SC 09.11.12 R-0 1 St Sub SC SC SC

Date No Revision Prep By Checked Approved

Project : (2x520 MW) HNPCL VIZAG TPS, A.P Project Package Air conditioning

Title CONTROL & OPERATION PHILOSOPHY OF AC SYSTEM Customer HINDUJA NATIONAL POWER CORPORATION LTD.

Principle Consultant MOTT MACDONALD, NOIDA Main Contractor Name Sign Date

Bharat Heavy Electricals Ltd. Power Sector Project Engineering

Management, Noida

Drawn Checked

Approved

Sub Contractor Name Date Submitted For Sterling and Wilson Limited Prep By SC 09.11.12 Approval

Benfish IT Tower 31, GN Block

Sector-V, Salt Lake City Kolkata-700 091

Checked SC 09.11.12

Approved SC 09.11.12

Job No: Scale-1:100 Sheet 1of 24 Rev No: 01

BHEL Drawing No: PE-V0-361-553-A105

PDF processed with CutePDF evaluation edition www.CutePDF.comPDF processed with CutePDF evaluation edition www.CutePDF.com

kap59470ESHA

kap5947025.02.2013

Compliance on Control Write Up A/C HNPCLPAGE NO DRG DESCRIPTION MM's COMMENT MADE VIDE MAIL DTD. 03.01.2013 S&W/CSSAPL COMMENT dtd. 15.01.2013 REMARKS

Cover Sheet BHEL to submit the P&ID for AC Plant-2, for reviewing the control philosophy of AC plant-2

Noted and submitted on 2901013

BHEL to clarify whether a separate I/O has been considered in the PLC for LOCAL/REMOTE selection.

Separate I/O not considered. Local/Remote selection will be in HMI graphics as soft selection switch.

CPU's shall not be loaded more than 60% of the individual capacity even under worst loading condition.

Noted & Agreed.Revised GA Drawings already submitted (PE-V9-361-553-I917)

Speed of the communication bus shall be 100Mbps PC - PLC communication bus is in ethernet 100Mbps

Bus and Data N/W loading shall in NO case be more than 60% of its capacity. Noted & Agreed.

Bus change over during failure shall be automatic and bump less. Noted & Agreed.BHEL to note that CPU, Communication Bus, I/O Modules, Power Supply etc shall be redundant.

Noted & Agreed. Revised drawing submitted PE-V9-361-553-I912, R-2

OWS/EOWS size shall be mentioned. Revised drawing submitted.PE-V9-361-553-I912, R-2

BHEL to mention the type of interface with main plant DCS. Ethernet. Revised drawing submitted.PE-V9-361-553-I912, R-2

BHEL to not that the OWS shall be 2 Nos and one shall be configured as Operator Work Station and the other as Engineering workstation.

Noted but in your PLC Comments it is mentioned that both will br EOWS, So we consider the same.

BHEL to mention the no and type of printers. Revised drawing submitted.PE-V9-361-553-I912, R-2

6 of 22 ESP for Unit-4 to be corrected to ESP for Unit-2 Corrected in revised control Write-up

1 os 22

6074537Text Box

CONTRACTOR: STERLING & WILSON LIMITED Project: (2x520 MW) HNPCL VIZAG TPS, A.P Package: AIR-CONDITIONING & VENTILATION SYSTEM DOCUMENT: CONTROL PHILOSOPHY FOR AIR CONDITIONG & VENTILATION SYSTEM DOC NO: PE-V0-361-553-A105 REV 01 15/01/2013

Page 1 of 22

CONTROL WRITE-UP

SYSTEM DESCRIPTION FOR PLC CONTROLLED AIR CONDITIONING SYSTEM A) PLC configuration B) Details of Air-Conditioning system Equipments. C) Operation Philosophy of Air-Conditioning Equipment D) Operation Philosophy of Strip heater, Pan Humidifier & 3-way bypass valve. A) PLC configuration: For the operation & control of complete AC system dedicated PLC / PC System has been envisaged. PLC with CPU, I/O panels (as required) shall be placed at different locations. The PLC panel C01 (CPU Rack) located in the TG Building AC plant room consist of CPU & I/O racks related to AC system. OWS cum EWS consists of 1 no. PC, Monitor & Ethernet Switches, from this OWS the total system can be operated, controlled & monitored based on the mode of operation selected. 1 nos. Remote I/O panels - C02 is located at Service building 1 no. Remote I/O panel C03 is provided at ESP- VFD 1 1 no. Remote I/O panel C04 is provided at ESP- VFD 2 Cable to be provided for PLC to remote I/O panels. Complete operation can be carried through PLC OWS in Local (Auto and Manual) mode as selected through Local (Auto and Manual) selector switch devised on the PLC OWS (HMI Graphics) for respective equipments. Status / indications can be seen on PC monitor in both Auto and manual mode.


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B) Details of Air conditioning system equipments:

1. Main Control Room (TG Building) (AC Plant 1) a) UNIT 1 b) ESP VFD Control room of Unit 1 c) ESP VFD Control room of Unit 2

2. Service Building (AC Plant-2)

B.1) LIST OF AIR CONDITIONING SYSTEM EQUIPMENT FOR AC-1, MAIN CONTROL ROOM AC-1 plant consists of the following major items which are controlled through Panel C01 located at Main Control Room area. - 3 Nos. Air Handling Units (AHU) : AHU 1/2 shall be located in the AHU Room at 17.0 M Level, In case of failure of any of AHUs 1/2, AHU 3 will start automatically. Motor driven Fan, Air filter & cooling coil comprises to Air handling unit. Each AHU is isolated with, motorized isolation valve from chilled waterside & motorized non-return damper from Airside, to isolate the unit if it is not operating. 2 Nos. Air Handling Units (AHU) : AHU 1 shall be located in the AHU Room at 8.5 M Level, In case of failure of AHU No 1, AHU 2 will start automatically. Motor driven Fan, Air filter & cooling coil comprises to Air handling unit. Each AHU is isolated with, motorized isolation valve from chilled waterside & motorized non-return damper from Airside, to isolate the unit if it is not operating. 5 Nos. Fan Coil Units (FCU) : 5 FCU shall be located at 0.0 M Level. 1 No. Fresh Air Fan (FAF) is provided in AHU room mentioned above. There will be no standby fans. Motorize Fire Damper for all supply and return air duct 4 Nos. Cooling Towers (CT) are categorized in two following groups:- Group#1 includes CT#1 & 2; both cooling tower fans can be selected in working OR standby mode. Group#2 includes CT#3 & 4, both cooling tower fans can be selected in working OR standby mode. Both groups are common for AC Plant-1; any of the groups can be selected as working. Maximum two CT are required to run at a time during normal process.


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4 Nos. Condenser water pumps (CWP) are categorized as:- Group#1 includes CWP#1 & 2; both pumps can be selected in working OR standby mode, Group#2 includes CWP#3 & 4, both pumps can be selected in working OR standby mode. Both groups are common for Plant-1; any of the groups can be selected. Maximum two CWPs are required to run at a time during normal process. 4 Nos. Chilled water pumps (CHWP) are categorized in two following groups:- Group#1 includes CHWP#1 & 2; both pumps can be selected in working OR standby mode, Group#2 includes CHWP#3 & 4; both pumps can be selected in working OR standby mode. Both groups are common for AC Plant-1; any of the groups can be selected. Maximum two CHWPs are required to run at a time during normal process. 4 Nos. Chiller Machines (CHM) along with their individual isolation valves are categorized in two groups; Group#1 includes CHM#1 & 2; both CHM can be selected in working OR standby mode, Group#2 includes CHM#3 & 4; both CHM can be selected in working OR standby mode. Maximum two CHMs are required to run at a time during normal process.

The CHMs will be controlled from respective Microprocessor Panels located on each CHM. AHU room of AC-1 system shall consist of following equipment O AHU O 1 no. Isolation Valve in chilled water outlet line of each AHU O 1 no. Isolation damper in AHU delivery duct of each AHU O 3-way bypass Valve in inlet water line of each AHU and Isolation valve in bypass line. O 1 no. Strip Heater & Fine Filter in conditioned air duct O 1 no Fresh air fan, FAF O Other accessories like temperature & RH Sensors, etc. O Motorize Fire Damper For Supply & Return Air Duct etc.


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B.2) LIST OF AIR CONDITIONING SYSTEM EQUIPMENTS FOR AC-2, SERVICE BUILDING AC-2 plant consists of the following major items that are controlled through Panel C02 located at service building Room area: - 5 Nos. of Air Handling Units (AHU) There are five elevations, one AHU is provided in each AHU room as below; Elevation 0 meter1 no. AHU Elevation 4.25 meter1 no. AHU Elevation 8.5 meter1 no. AHU Elevation 12.75 meter1 no. AHU Elevation 17.0 meter1 no. AHU Motor driven Fan, Air filter & cooling coil comprises to Air handling unit. No stand by unit is envisaged. 1 No. Fresh Air Fan (FAF) is provided per AHU room, Five AHU room comprises to 5 Fresh Air Fans, and No stand by unit is envisaged. 2 Nos cooling towers (CT), 1W + 1S are provided; Both the Cooling Tower Fans are facilitating to run in working as well as standby mode. Any one CT can be selected as working & remaining one can be selected as standby. If one of the running CT fails the standby CT will start automatically. 2 Nos condenser water pumps (CWP), 1W + 1S are provided; Both the pumps are facilitate to run in working as well as standby mode. Any one CWP can be selected as working pump & remaining one can be selected as standby pump. If one of the running CWP fails the standby CWP will start automatically. 2 Nos chilled water pumps (CHWP), 1W + 1S are provided; Both the pumps are facilitate to run in working as well as standby mode. Any one CHWP can be selected as working pump & remaining one can be selected as standby pump. If one of the running CHWP fails the standby CHWP will start automatically.


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2Nos. Chiller Machines (CHM), 1W+1S are provided along with their individual isolation valves. Both the CHMs are facilitate to run in working as well as standby mode. Any one CHMs can be selected as working chiller machine & remaining one can be selected as standby chiller machine. If one of the running CHM fails the standby CHM will start automatically. Maximum one CHMs are required to run at a time during normal process.

Individual AHU room of AC-2 shall consist of following equipments

o One no. AHU per room o 3-way bypass Valve in inlet water line of each AHU and Isolation valve in bypass line. o 1 no. Strip Heater & Fine Filter in conditioned air duct o 1Nos Fresh air fan, FAF o Other accessories like temperature & RH Sensors, etc o Motorize Fire Damper For Supply & Return Air Duct etc.

B.3) LIST OF AIR CONDITIONING SYSTEM EQUIPMENT OF AC-1, ESP VFD CONTROL ROOM ESP plant consists of the following major items which are controlled through Panel C03 located at ESP-3 Control Room area. 3 Nos. Air Handling Units (AHU) for ESP VFD 1: AHU 1/2 shall be started in the AHU Room of unit 1, In case of failure of any of AHUs 1/2, AHU 3 will start automatically. Motor driven Fan, Air filter & cooling coil comprises to Air handling unit. Each AHU is isolated with, motorized isolation valve from chilled water outlet side & motorized non-return damper from Airside, to isolate the unit if it is not operating.

1 Nos. Fresh Air Fan (FAF) are provided in each AHU room for unit-1,


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ESP-VFD Control Room shall consist of following equipment O AHU O 1 no. Isolation Valve in chilled water outlet line of each AHU O 1 no. Isolation damper in AHU delivery duct of each AHU O 3-way bypass Valve between inlet & outlet chilled water line of each AHU O 1 no. Strip Heater & Fine Filter in conditioned air duct O 1 nos. Fresh air fan, FAF O Other accessories like temperature & RH Sensors, etc. O Motorize Fire Damper For Supply & Return Air Duct etc. B.4) LIST OF AIR CONDITIONING SYSTEM EQUIPMENT OF AC-2, ESP VFD-4 CONTROL ROOM ESP plant consists of the following major items which are controlled through Panel C04 located at ESP-4 Control Room area. - 3 Nos. Air Handling Units (AHU) for ESP VFD 2 : AHU 1/2 shall be Started in the AHU Room of unit 2 , In case of failure of any of AHUs 1/2, AHU 3 will start automatically. Motor driven Fan, Air filter & cooling coil comprises to Air handling unit. Each AHU is isolated with, motorized isolation valve from chilled water outlet side & motorized non-return damper from Airside, to isolate the unit if it is not operating.

1 Nos. Fresh Air Fan (FAF) are provided in AHU room for unit-2, ESP for unit-2 of ESP-VFD Control Room shall consist of following equipment O AHU O 1 no. Isolation Valve in chilled water outlet line of each AHU O 1 no. Isolation damper in AHU delivery duct of each AHU O 3-way bypass Valve between inlet & outlet chilled water line of each AHU O 1 no. Strip Heater & Fine Filter in conditioned air duct O 1 nos. Fresh air fan, FAF O Other accessories like temperature & RH Sensors, etc. O Motorize Fire Damper For Supply & Return Air Duct etc.


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C) Operating philosophy for Air-Conditioning Equipment C.1) AC-1 for unit-1 & 2: Manual mode, START operation: Step#1 (Local mode/Remote mode): Select the Fresh Air Fan (FAF) from OWS selection button as working fan. If the breaker is OK, the Fan will start. Step#2 (Local mode/Remote mode): Out of 3 Nos. of Air Handling Units (AHU) 1/2/3), in AC -1, minimum 2 AHUs need to be started. Select three AHUs from OWS as a working & remaining one as standby AHU. Start the selected AHUs from OWS. PLC will automatically check the interlock of either of FA fan of respective AHU room is running. In case of failure/trip of any of working AHUs, standby AHU will start automatically. While starting the standby AHU, it will also cross check whether FAF is running or not. Out of 2 Nos. of Air Handling Units (AHU- 1/2), in AC -1, minimum 1 AHUs need to be started. Select one AHUs from OWS as a working & remaining one as standby AHU. Start the selected AHUs from OWS. PLC will automatically check the interlock of either of FA fan of respective AHU room is running. In case of failure/trip of any of working AHUs, standby AHU will start automatically. While starting the standby AHU, it will also cross check whether FAF is running or not. Out of 5 Nos. of Fan Coil Units (FCU-1/2/3/4/5), in AC -1, minimum 1 FCU need to be started. Start the selected FCUs from OWS. FAF is necessary to be running to operate the either of AHU. Monitoring of supply and return air Motorize Fire Damper


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Step#3 (Local mode/Remote mode): Check the level of water in cooling tower basin & the makeup water tank through level switches. Level switches will give indication in case the water level is low in the respective areas. If the water level is o.k., then maximum two nos Cooling Tower Fan can be operated, at any given time. CT#1 & 2; two cooling tower fans can be selected in working and other two as standby mode. Cooling Towers are grouped in two; both groups are common for AC Plant 1 Group #1 comprise to: CT#1 & 2 Group #2 comprise to: CT#3 & 4 Maximum Two CTs can be operated to deliver the condenser water to AC Plant-1, at any given time . Either of group can be selected from the OWS CRT, if group#1 is selected group#2 should remain as a Standby. If group#1 is selected: start the CT#1 from OWS CRT, after some time delay start CT#2 start from OWS CRT, if either of CT fans fails to start or trips in running, PLC will automatically start the CT#3. If CT#3 & either of CT#1 or CT#2 is running & any one of the two is tripped, PLC will automatically start the CT#4. At any given time logic will ensure that TWO CTs are running. If group#2 is selected: start the CT#3 from OWS CRT, after some time delay start CT#4 from OWS CRT, if either of CT fails to start or trips in running, PLC will automatically start the CT#1. If CT#1 & either of CT#3 or CT#4 is running & any one of the two is tripped, PLC will automatically start the CT#2. At any given time logic will ensure that TWO CTs are running. PLC will check the following safeties before starting the CT. a) Minimum 1 AHU is running b) Breaker fault/trip is not available. If any one of the CT trips & standby CT starts, standby CT will also check the permits, which were complied for tripped CT. All four CTs are common for Plant-1; Working & standby grouping is made to ensure the uniform utilization of equipments. Step#4 (Local mode/Remote mode): CW pumps are grouped in two groups; both groups are common for Plant-1


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Group #1 comprise to: CWP#1 & 2 Group #2 comprise to: CWP#3 & 4 Maximum Two pumps can be operated to deliver the condenser water to Plant-1, at any given time . Either of group can be selected from the OWS CRT, if group#1 is selected group#2 should remain as a Standby. If group#1 is selected: start the CWP#1 from OWS CRT, after some time delay start CWP#2 start from OWS CRT, if either of pump fails to start or trips in running, PLC will automatically start the CWP#3. If CWP#3 & either of CWP#1 or CWP#2 is running & any one of the two is tripped, PLC will automatically start the CWP#4. At any given time logic will ensure that TWO CWPs are running. If group#2 is selected: start the CWP#3 from OWS CRT, after some time delay start CWP#4 from OWS CRT, if either of pump fails to start or trips in running, PLC will automatically start the CWP#1. If pump#1 & either of CWP#3 or CWP#4 is running & any one of the two is tripped, PLC will automatically start the CWP#2. At any given time logic will ensure that TWO CWPs are running. PLC will check the following safeties before starting the CWP. a) Minimum 1 CT Fan is running b) Breaker fault/trip is not available. If any one of the CWP trips & standby CWP starts, standby CWP will also check the permits, which were complied for tripped CWP. All four CWPs are common for Plant-1; grouping is made to ensure the uniform utilization of equipments. Step#5 (Local mode/Remote mode): CHW pumps are grouped in two groups; both groups are common for unit-3 & unit-4 Group #1 comprise to: CHWP#1&2 Group #2 comprise to: CHWP#3&4 Maximum two pumps can be operated to deliver the chilled water to Plant-1 AHUs, at any given time Either of group can be selected from the OWS CRT, if group#1 is selected group#2 should remain as a Standby.


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If group#1 is selected: start the CHWP#1 from OWS CRT, after some time delay start CHWP#2 start from OWS CRT, if either of pump fails to start or trips in running, PLC will automatically start the CHWP#3. If CHWP#3 & either of CHWP#1 or CHWP#2 is running & any one of the two is tripped, PLC will automatically start the CHWP#4. At any given time logic will ensure that TWO CHWPs are running. If group#2 is selected: start the CHWP#3 from OWS CRT, after some time delay start CHWP#4 from OWS CRT, if either of pump fails to start or trips in running, PLC will automatically start the CHWP#1. If pump#1 & either of CHWP#3 or CHWP#4 is running & any one of the two is tripped, PLC will automatically start the CHWP#2. At any given time logic will ensure that TWO CHWPs are running. PLC will check the following safeties before starting the CHWP. a) Minimum 1 CWP is running b) Breaker fault/trip is not available. If any one of the CHWP trips & standby CHWP starts, standby CHWP will also check the permits, which were complied for tripped CHWP. All four CHWPs are common for both units; grouping is made to ensure the uniform utilization of equipments. Step# 6 (Local mode/Remote mode): 4 no. Chiller machines are grouped in two groups, both groups are common for Plant-1, individual isolation valve at discharge of CHM are considered as an integral part of CHM. Group #2 comprise to: CHM#3 & 4, along with their isolation valves. Maximum Two CHMs can be operated to chill the water, so as to cater it to Plant-1 AHUs, at any given time. Maximum Two CHW pump running to be ensured to operate the chiller machines & their isolation valves. Either of group can be selected, if group#1 is selected group#2 should remain as a Standby. If group#1 is selected: Open the isolation valve of CHM#1, after a delay of some time, & isolation valve opening is ensured, start the CHM#1 from PLC. Similarly, open the isolation valve of CHM#2, after a delay of some time, & isolation valve opening is ensured, start the CHM#2. PLC will ensure that, the respective isolation valve is open before starting the Chiller.


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If either of Chiller Machine fails to start or trips in running, PLC will automatically open the isolation valve of CHM#3 & start the CHM#3. If CHM#3 & either of CHM#1 or CHM#2 is running & any one of the two is tripped, PLC will automatically open the isolation valve of CHM#4 & start the CHM #4 . At any given time logic will ensure that TWO CHMs are running. If group#2 is selected : Open the isolation valve of CHM#3 from PLC, after a delay of some time , & isolation valve opening is ensured, start the CHM#3 from PLC. Similarly, open the isolation valve of CHM#4 from PLC, after a delay of some time, & isolation valve opening is ensured, start the CHM#4 from PLC. PLC will ensure that, the respective isolation valve is open before starting the Chiller. If either of Chiller Machine fails to start or trips in running, PLC will automatically open the isolation valve of CHM#1 & start the CHM#1. If CHM#1 & either of CHM#3 or CHM#4 is running & any one of the two is tripped, PLC will automatically open the isolation valve of CHM#2 & start the CHM #2. At any given time logic will ensure that TWO CHMs are running. Isolation valve is considered as a part of chiller machine, once the isolation valve is opened & open limit switch feedback is acknowledged by PLC, then only PLC can permit to start the respective chiller machine. Group selection of isolation valve & respective CHM is strictly same. PLC will check the following safeties before opening the isolation valves of chiller machines & starting the chiller machines: a) Minimum 1 CHWPs are running b) Chiller panel fault/trip is not available. c) Group safety fault is not available. If any one of the Chiller machine/isolation valve trips & standby chiller machine/isolation valve starts, standby Chiller machine/isolation valve will also check the permits which were complied for tripped Chiller machine/isolation valve. All four chiller machines along with their isolation valves are common for both units, grouping is made to ensure the uniform utilization of equipments. Selection/De-selection of standby is through toggle function for all standby applications.


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Manual mode STOP operation (Local mode/Remote mode): a) Stop the Chiller machines b) Close the isolation valves c) Stop the Chiller water pumps d) Stop the Condenser water pumps e) Stop the Cooling Tower Fans f) Close the isolation valves & isolation dampers of AHUs g) Stop the running AHUs h) Stop the Running Fresh Air fans

Stop operation is done from PLC OWS in Local mode. START operation in Auto mode (Local /Auto): A common Auto button is envisaged on OWS screen of PLC, if this button is pressed, entire system for Plant-1 will turn into Auto mode operation.

Select working Fresh air fan Select either of two working AHUs & one standby AHU for Plant-1 Select either of CT group as working & another group as standby Select either of CWP group as working & another group as standby Select either of CHWP group as working & another group as standby Select either of CHM group (along with their isolation valve) as working & remaining

group as standby

Once the operator gives common Auto start command, following operation will takes place

If the breaker is OK, the Fan will start.

PLC will automatically check the interlock of either of FA fan from AHU room is running & will start the selected working AHUS, In case of failure/trip of any of working AHUs, standby AHU will start automatically.

While starting the standby AHU, it will also cross check the FAF is running. FAF is necessary to be running to operate the either of AHU. Monitoring of supply and return air Motorize Fire Damper

If the operation of minimum one AHU is ensured, PLC will start the first CT in

working group, after a delay of 6 seconds, PLC will start another working CT. If the operation of minimum one CT is ensured, PLC will start the first CWP in

working group, after a delay of 6 seconds, PLC will start another working CWP.


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If the operation of minimum one CWP is ensured, PLC will start the first CHWP in working group, after a delay of 6 seconds, PLC will start another working CHWP.

If the operation of minimum one CHWP running is ensured, the isolation valves on running chiller machine will open. (Time delay of 6 second is provided between CHWP start & isolation valve opening)

Once the opening of isolation valves of CHM is ensured by its limit switch feedback from PLC in sequential operation.

The standby operation of AHUs for Plant-1, Cooling Tower Group ,CWP group,CHWP per group & Chiler machine per group along with their isolation valves is taken care by PLC & the operation will remain same as explained in manual mode operation.

STOP operation in Auto mode (Local /Remote): A common Auto-stop button is envisaged on OWS CRT screen of PLC, if this button is pressed, entire system for unit-3 & unit-4 will turn into Auto-stop mode operation & PLC will take following actions; a) Stop both the Chiller machines b) Close both the isolation valves of chiller machines c) Stop the Chiller water pump d) Stop the Condenser water pump e) Stop Cooling Tower Fan f) Close both the isolation valves & isolation dampers of running AHUs g) Stop all the running AHUs h) Stop all the Running Fresh Air fans

C.2) AC-2 for Service Building: Manual mode, START operation: Step#1 (Local/Remote): There are five separate AHU rooms considered in AC-2, each AHU room consists of one AHU. Common CT, CWP, CHWP & CHM provides chilled water for all five AHUs. Depends on requirement, an individual AHU can be taken into operation. A selection button is provided on OWS CRT to select or deselect the particular AHU. Select the Fresh Air Fan (FAF) as working, from OWS selection button. Start the FAF from OWS CRT. If the breaker is OK, the Fan will start.


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Step#2 (Local /Remote): Start Air Handling Units (AHU) from OWS for individual AHU room. PLC will automatically cross check the interlock of either of FA fan of respective AHU room is running. Similar operation can be followed for all three elevations like: Elevation 0 meter1 no. AHU Elevation 4.25 meter1 no. AHU Elevation 8.5 meter1 no. AHU Elevation 12.75 meter1 no. AHU Elevation 17.0 meter1 no. AHU FAF is necessary to be running to operate the AHU. Monitoring of supply and return air Motorize Fire Damper Step#3 (Local /Remote): Check the level of water in cooling tower basin & the makeup water tank through level switches. Level switches will give indication in case the water level is low in the respective areas. If the water level is o.k., then maximum one Cooling Tower Fan can be operated. , at any given time. Out of two CTs, maximum one CT can be running at any time, any one CTs can be selected as working & the other one is necessarily to be selected as standby. Start working selected CT-1 & 2 from OWS, If the running CTs, either one fails, the standby CT will start automatically. PLC will check the following safeties before starting the CT Fan : a) Minimum 1 AHU is running b) Breaker fault/trip is not available. If any one of the CT trips & standby CT starts, standby CT will also check the permits which were complied for tripped CT Fan. Both CTs are common for all five elevations , standby logic is developed to ensure the uniform utilization of equipments. Selection/De selection of standby is through toggle function for all standby applications.


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Step#4 (Local /Remote): Out of two CWPs, maximum one CWP can be running at any time, Either one CWP can be selected as working & the other one is necessarily to be selected as standby. Start working selected CWP-1/2 from OWS CRT, If the running CWP fails, either one, the standby CWP will start automatically. PLC will check the following safeties before starting the CWP: a) CT Fan is running b) Breaker fault/trip is not available. If any one of the CWP trips & standby CWP starts, standby CWP will also check the permits which were complied for tripped CWP. Both CWPs are common for all five elevations , standby logic is developed to ensure the uniform utilization of equipments. Selection/De selection of standby is through toggle function for all standby applications. Step#5 (Local /Remote): Out of two CHWP, maximum one CHWP can be running at any time, Either one CHWP can be selected as working & the other one is necessarily to be selected as standby. Start working selected CHWP-1 /2 from OWS If the running CHWP fails, either one the standby CHWP will start automatically. PLC will check the following safeties before starting the CHWP : a)Minimum 1 CWP is running b)Breaker fault/trip is not available. If any one of the CHWP trips & standby CHWP starts, standby CHWP will also check the permits which were complied for tripped CHWP. Both CHWPS are common for all five elevations , standby logic is developed to ensure the uniform utilization of equipments. Selection/De selection of standby is through toggle function for all standby applications.


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Step# 6 (Local /Remote): Maximum one CHM can be operated to chill the water, so as to cater it to all five AHUs, at any given time. Out of two chiller machines along with their isolation valves, maximum one chiller machine can be operated to chill the water , at any time. Either one chiller machine along with its isolation valves can be selected as working & the remaining is necessarily to be selected as standby. Open the isolation valve of as working selected chiller machine from PLC, Start the working selected chiller machine from PLC, so as to pass on the command at chiller local panel for sequential operation. If the running CHM is failed, the standby CHM along with its isolation valve will start automatically. PLC will check the following safeties before opening the isolation valves of chiller machines & starting the chiller machines: a) 1 CHWP is running b) Chiller panel fault/trip is not available. c) Group safety fault is not available If any one of the Chiller machine/isolation valve trips & standby chiller machine/isolation valve starts, standby Chiller machine/isolation valve will also check the permits which were complied for tripped Chiller machine/isolation valve. Manual mode STOP operation (Local mode/Remote mode):

a) Stop the Chiller machines from PLC b) Close the isolation valves from the PLC c) Stop the Chiller water pumps from OWS CRT d) Stop the Condenser water pumps from OWS CRT e) Stop the Cooling Tower from OWS CRT f) Stop the running AHUs g) Stop the Running Fresh Air fans

Stop operation is done from PLC OWS CRT in Local mode.


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START operation in Auto mode (Local /Auto): A common Auto button is envisaged on OWS CRT screen of PLC, if this button is pressed, entire system for below mentioned elevation will turn into Auto mode operation. Elevation 0 meter, Elevation 4.25 meter, Elevation 8.5 meter, Elevation 12.75,AHU Elevation 17.0

Select working Fresh air fan for all five elevations Select the AHUs those are required to be operated, per elevation Select one CTs as working & remaining one as standby. Select one CWs pumps as working & remaining one as standby Select one CHWs pump as working & remaining one as standby Select one CHM (along with their isolation valve) as working & remaining one as

standby. Once the operator gives common Auto start command, following operation will takes place;

If the breaker is OK, the selected Fresh air Fan of AHU will start.

PLC will automatically check the interlock of either of FA fan from AHU room is running & will start the selected working AHU.

FAF is necessary to be running to operate the AHU. Monitoring of supply and return air Motorize Fire Damper.

If the operation of minimum one AHU is ensured, PLC will start the first working

selected CT Fan , then one no CWP, Then one CHWP If one CHWP running is ensured, the isolation valves on the working selected chiller

machine will open. (Time delay of 6 second is provided between CHWP start & isolation valve opening)

Once the opening of isolation valves of CHM is ensured by its limit switch feedback from PLC, a command is issued by PLC to Chiller panel to start the chiller machine in sequential operation.

The standby operation of CHWP & Chiler machine along with their isolation valves is taken care by PLC & the operation will remain same as explained in manual mode operation.


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Selection/De-selection of standby is through toggle function for all standby applications. STOP operation in Auto mode(Local /Remote): A common Auto-stop button is envisaged on OWS CRT screen of PLC, if this button is pressed, entire system for AC-2 will turn into Auto-stop mode operation & PLC will take following actions;

a) Stop both the Chiller machine b) Close both the isolation valves of chiller machine

c) Stop both the Chiller water pump d) Stop both the Condenser water pump e) Stop both the Cooling Tower Fan f) Stop all the running AHU g) Stop all the Running Fresh Air fan

C.3) ESP-1, VFD -3 control room Building: Manual mode, START operation: Step#1 (Local mode/Remote mode): Select the Fresh Air Fan (FAF) from OWS selection button as working fan. If the breaker is OK, the Fan will start. Step#2 (Local mode/Remote mode): Out of 3 Nos. of Air Handling Units (AHU) 1/2/3, in ESP-1, maximum 2 AHUs need to be started. Select two AHUs from OWS CRT as a working & remaining one as standby AHU. Start the selected AHUs from OWS CRT. PLC will automatically check the interlock of either of FA fan of respective AHU room is running. In case of failure/trip of any of working AHUs, standby AHU will start automatically. While starting the standby AHU, it will also cross check whether FAF is running or not. FAF is necessary to be running to operate the either of AHU. Monitoring of supply and return air Motorize Fire Damper STOP operation in manual mode(Local /Remote): a) Stop the running Air Handling Units


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b) Stop the Running Fresh Air fan Select the UAF Pumps from OWS selection button as working and rest as stand by. If the breaker is OK, the Pump will start. Select the UAF Fans from OWS selection button as working. If the breaker is OK, the Fan will start. Step#2 (Local mode/Remote mode): Out of 2 Nos. of Pumps, in unit-3, minimum 1 Pump need to be started & remaining one as standby Pump. Start the selected Pumps from OWS. In case of failure/trip of any of working Pump, standby Pump will start automatically. 1 No. of UAF Fan, in unit-3, minimum 1 Pump needs to be started. C.4) ESP-VFD-4 control room Building: Manual mode, START operation: Step#1 (Local mode/Remote mode): Select the Fresh Air Fan (FAF) from OWS selection button as working fan. If the breaker is OK, the Fan will start. Step#2 (Local mode/Remote mode): Out of 3 Nos. of Air Handling Units (AHU) 1/2/3, in ESP-1, maximum 2 AHUs need to be started. Select two AHUs from OWS CRT as a working & remaining one as standby AHU. Start the selected AHUs from OWS CRT. PLC will automatically check the interlock of either of FA fan of respective AHU room is running. In case of failure/trip of any of working AHUs, standby AHU will start automatically. While starting the standby AHU, it will also cross check whether FAF is running or not. FAF is necessary to be running to operate the either of AHU. Monitoring of supply and return air Motorize Fire Damper


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STOP operation in manual mode(Local /Remote): a) Stop the running Air Handling Units b) Stop the Running Fresh Air fan Select the UAF Pumps from OWS selection button as working and rest as stand by. If the breaker is OK, the Pump will start. Step#2 (Local mode/Remote mode): Out of 2 Nos. of Pumps, in unit-3, minimum 1 Pump need to be started & remaining one as standby Pump. Start the selected Pumps from OWS. In case of failure/trip of any of working Pump, standby Pump will start automatically. 1 No. of UAF Fan, in unit-3, minimum 1 Pump need to be started. D) Operation Philosophy of Strip heater, Pan humidifier , 3-way bypass valve & Fire Damper. 3 way bypass valve:- It is fixed in the return chilled water line of the AHU circuit and having a bypass connection with the supply line bypassing the chilled water coil of AHU. It consist of a 3 way valve, a actuator and a controller. It operates against the input received from temperature (TS) located in return air Path at AHU room. When TS indicates that temp. of return is lower than the designed temp. then 3 way bypass valve start bypassing proportionate amount of chilled water from supply line to directly to return line of AHU chilled water circuit. Thus not allowing full chilled water flow in the AHU coil. Then when TS indicates that temperature of return is higher that than the designed temp. then 3 way bypass valve allows the required chilled water to flow to AHU coil and minimize the bypass of chilled water proportionately. Thus 3 ways mixing vale always modulates the chilled water flow as per the feedback of TS. Strip heater: - Strip heaters are required to add sensible heat at monsoon season. These are fixed at the supply duct of AHU or common plenum. These are having banks of heaters. It will be operative as per the signal received from R H Sensor. RH sensor senses the relative humidity (RH) of the return air at the AHU room. If the RH is more than designed RH then it gives signal, on command to strip heater. When the RH sensor have a reading that RH of return air is within range of designed temperature it then gives input to heater contactors i.e., off command to strip heater.


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Pan humidifier: - Pan humidifiers are required to add humidity at supply air at winter season. It consists of few heater coils immersed at a confined tank . When these heaters get operated the water starts boiling and the vapor from the tank get delivered to supply duct with the help of a probe. It will be operative as per the signal received from R H Sensor. R H Sensor will generate on/off signal . RH sensor senses the relative humidity (RH) of the return air at the AHU room. If the RH is less than designed RH then it gives signal to pan humidifier. It will start generating vapor and will supply it to supply air duct. When the RH sensor have a reading that RH of return air is within range of designed temperature it then gives off command to pan humidifier. AHU Fans and other related equipment as per requirement of process will trip in case of fire on receiving signal from Fire Panel. Fire Damper position will be monitored in PLC. Fire Dampers will be operated (power feeding) from Fire Damper Control panel based on fire signal. E) Details of Air Washer Ventilation Equipment F) Operation Philosophy of Air Washer Ventilation Equipment E) Air Washer Ventilation Equipment Ventilation system plant is located at following areas: E.1) Air Washer Ventilation System Equipment a, TG BLDG UNIT-3 Equipment list: 16 nos. Air washer Fan (8W +8 SB) 16 no. Pumps (8W +8 SB) E.2) UAF for Ventilation System Equipment at ESP-1 Equipment list : 1 no. UAF Fan 2 no. Pumps (1W +1 SB)


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E.3) UAF for Ventilation System Equipment at ESP-2 Equipment list : 1 no. UAF Fan 2 no. Pumps (1W +1 SB) F.) Operation Philosophy for Air Washer Ventilation Systems: Local mode /Remote mode:

a) Fan operation : Air washing Fan can be started from the Local Control Panel in local mode. If breaker is in healthy condition the Fan will start. During running condition, if fan trips, the RUN status on LCP will change to TRIP status along with annunciation in the control room.

b) Wash water pump operation : Pumps are facilitate to run in working as well as standby mode. Any one wash water pump can be selected as working pump & remaining one can be selected as standby pump from LCP. Selected pump can be started & stoped from LCP. If running wash water pump fails the standby pump will start automatically. If, water level of the air washer tank is low then all the pumps will trip. And if the pressure at common discharge of the pump falls below 2.5 Kg/cm2 then the working pump will automatically change over to stand by pump and the stand by pump will turn to working pump and the same will be controlled and monitored in PLC. Selection/Deselction of standby is through toggle function for all standby applications. Same philosophy is applicable for all Air washer fans & air washer pumps.

Cover Page.pdfCompliance for HNPCL Control Write UpControl Write Up AC Vent - HNPCL R-1

2013-02-21T13:24:14+0530Vivek Kumar

control & operation philosophy of ac

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