A0002 SHEET MI802.pdf

SEQUENCE OF OPERATION:

CONDENSER WATER SYSTEM COOLING POINTS LIST:

(CONDENSER WATER SYSTEM COOLING)

COOLING TOWER SYSTEM CONSISTS OF ONE (1) COOLING TOWER, TWO (2) TOWER

INLINE CENTRIFUGAL PUMPS (P-3 & P-4) OPERATING IN LEAD-STANDBY

CONFIGURATION, AND ONE PLATE AND FRAME HEAT EXCHANGER.

RUN CONDITIONS:

THE COOLING TOWER SYSTEM SHALL BE ENABLED BY THE BAS TO RUN

WHENEVER:

- THE MAIN CONDENSER SYSTEM IS ENABLED

- AND THE OUTSIDE AIR WET BULB TEMPERATURE IS GREATER THAN 37°F (ADJ.)

THE BAS SHALL MONITOR THE CONDENSER WATER SUPPLY TEMPERATURE AND

ON A RISE IN TEMPERATURE ABOVE 93°F (ADJ.) FOR 5 MINUTES (ADJ.) THE

COOLING TOWER SYSTEM SHALL BE ENERGIZED, THE TOWER ISOLATION VALVE

(V-1) SHALL OPEN, THE HEAT EXCHANGER TOWER WATER ISOLATION VALVE (V-4)

SHALL OPEN, LEAD TOWER PUMP (P-3 OR 4) SHALL BE ENERGIZED. UPON PROOF

OF TOWER WATER TEMPERATURE BELOW 87°F (ADJ.) THE HEAT EXCHANGER

CONDENSER WATER ISOLATION VALVE (V-4) SHALL BE OPENED AND CONDENSER

WATER DIVERTING VALVE (V-5) SHALL BE MODULATED OPEN TO MAINTAIN

DIFFERENTIAL PRESSURE FOR HEAT EXCHANGER. UPON A DROP IN CONDENSER

WATER SUPPLY WATER TEMPERATURE TO BELOW 87°F (ADJ.) THE LEAD TOWER

WATER PUMP (P-3 OR 4) SHALL BE DE-ENERGIZED, HEAT EXCHANGER ISOLATION

VALVES (TOWER V-3 AND CONDENSER V-4) SHALL BE CLOSED.

ON A DROP IN THE CONDENSER WATER RETURN TEMPERATURE BELOW 90°F (ADJ.)

FOR 5 MINUTES (ADJ.) THE COOLING TOWER SYSTEM SHALL BE DE-ENERGIZED

AND THE TOWER PUMPS (P-3 OR P-4) SHALL BE DE-ENERGIZED, TOWER ISOLATION

VALVE (V-1) SHALL CLOSE, TOWER BY-PASS VALVE (V-2) SHALL OPEN TO BY-PASS,

HEAT EXCHANGER ISOLATION VALVES (TOWER V-3) AND (CONDENSER V-4) SHALL

CLOSE, AND DIVERTING VALVE (V-5) SHALL OPEN TO HEAT EXCHANGER BY-PASS

TOWER BASIN TEMPERATURE SHALL BE RESET TO AMBIENT WET BULB PLUS 5

DEGREES (ADJ.) TO A MAXIMUM OF 85°F (ADJ.) AND MINIMUM OF 45°F (ADJ.). UPON

A RISE IN BASIN TEMPERATURE ABOVE SET POINT TOWER BY-PASS VALVE (V-2)

SHALL BE OPENED TO FLOW OVER TOWERS. UPON A CONTINUED RISE IN BASIN

TEMPERATURE FOR 5 MINUTES (ADJ.), COOLING TOWER FAN (CT-1) SHALL BE

ENERGIZED AND FAN SPEED MODULATED TO MAINTAIN BASIN TEMPERATURE

SETPOINT.

TO PREVENT SHORT CYCLING, THERE SHALL BE A USER DEFINABLE DELAY (10 MIN

ADJ) BETWEEN ENERGIZING AND DE-ENERGIZING THE COOLING TOWER SYSTEM.

ON FAILURE OF TOWER FAN OR EXCESSIVE VIBRATION THE FAILED TOWER FAN SHALL

BE DE-ENERGIZED, TOWER ISOLATION VALVE SHALL BE CLOSED, AND ALARM SENT TO

OPERATOR.

THE CONTROLLER SHALL MONITOR THE COLD WATER BASIN LEVEL THROUGH A SERIES

OF WATER LEVEL SWITCHES:

-IF THE BASIN LEVEL RISES ABOVE THE HIGH WATER LEVEL SWITCH, TURNING IT

ON, AN ALARM SHALL BE GENERATED.

-IF THE BASIN LEVEL DROPS BELOW THE LOW WATER MAKEUP SWITCH, TURNING

IT ON, AN ALARM SHALL BE GENERATED AND THE MAKEUP VALVE SHALL OPEN.

-IF THE BASIN LEVEL DROPS BELOW THE LOW WATER LEVEL SWITCH, TURNING IT

ON, AN ALARM SHALL BE GENERATED AND THE COOLING TOWER AND CHILLER

SHALL BE SHUTDOWN.

ON FAILURE OF ANY DUTY PUMP THE STANDBY PUMP SHALL BE ENERGIZED AND THE

FAILED PUMP SHALL BE DE-ENERGIZED AND ALARM GENERATED.

ON FAILURE (HIGH OR LOW DIFFERENTIAL PRESSURE) OF HEAT EXCHANGER, HEAT

EXCHANGER ISOLATION SHALL BE CLOSED, THE COOLING TOWER SYSTEM SHALL BE

DE-ENERGIZED, AND ALARM GENERATED.

THE DESIGNATED LEAD PUMP SHALL ROTATE UPON ONE OF THE FOLLOWING USER

SELECTABLE CONDITIONS:

- MANUALLY THROUGH A SOFTWARE SWITCH

- IF RUNTIME (ADJ.) IS EXCEEDED

- DAILY

- WEEKLY

- MONTHLY

SIDESTREAM FILTER SYSTEM

FILTER SYSTEM (SSF-1) SHALL RUN CONTINUOUSLY WHENEVER COOLING TOWER

SYSTEM IS ENABLED. FILTER FLUSH CYCLE SHALL BE ENABLED WHENEVER FILTER

DIFFERENTIAL PRESSURE IS GREATER THAN 7 PSI (ADJ.).

TANK CIRCULATION:

BAS SHALL MONITOR SYSTEM OPERATION. IF THE PUMP HX SYSTEM HAS NOT

OPERATED FOR ONE (1) WEEK (ADJ.) HX ISOLATION VALVE (V-3) AND TOWER ISOLATION

VALVE (V-1) SHALL BE OPENED AND LEAD PUMP SHALL BE ENERGIZED. AFTER A

RUNTIME OF 30 MINUTES (ADJ.) PUMP SHALL BE DE-ENERGIZED AND ISOLATION VALVE

CLOSED.

EMERGENCY SHUTDOWN:

THE BAS SHALL SHUT DOWN SYSTEM UPON RECEIVING AN EMERGENCY SHUTDOWN

SIGNAL FROM AN EMERGENCY SHUTDOWN SWITCH. RESET SHALL BE MANUAL BY A

CENTRAL STATION DDC COMMAND SIGNAL

ALARMS:

- FAN

FAILURE: COMMANDED ON, BUT THE STATUS IS OFF

IN HAND: COMMANDED OFF, BUT THE STATUS IS ON

RUNTIME EXCEEDED: STATUS RUNTIME EXCEEDS A USER DEFINABLE LIMIT

FAN VFD FAULT

- PUMP(S)

FAILURE: COMMANDED ON, BUT THE STATUS IS OFF

IN HAND: COMMANDED OFF, BUT THE STATUS IS ON

RUNTIME EXCEEDED: STATUS RUNTIME EXCEEDS A USER DEFINABLE LIMIT

PUMP VFD FAULT

- BASIN

HIGH WATER LEVEL

LOW MAKEUP WATER LEVEL

LOW WATER LEVEL

- HEAT EXCHANGER(S)

FAILURE: HIGH DIFFERENTIAL PRESSURE

FAILURE: LOW DIFFERENTIAL PRESSURE

-FILTER SYSTEM

FAILURE: COMMANDED ON, BUT THE STATUS IS OFF

IN HAND: COMMANDED OFF, BUT THE STATUS IS ON

RUNTIME EXCEEDED: STATUS RUNTIME EXCEEDS A USER DEFINABLE LIMIT

HIGH FILTER DIFFERENTIAL PRESSURE: DIFFERENTIAL PRESSURE EXCEEDS A

USER DEFINABLE LIMIT

- HIGH TOWER WATER SUPPLY TEMPERATURE

- LOW TOWER WATER SUPPLY TEMPERATURE

- HIGH TOWER BASIN TEMPERATURE

- LOW TOWER BASIN TEMPERATURE

- EXCESSIVE TOWER VIBRATION

CONDENSER WATER SYSTEM COOLING CONTROL DIAGRAM

SCALE: NTS

COOLING TOWER YARDMECHANICAL ROOM

CT-1

V-1

VM

CT

V F D

CT

V F D

TOWER WATER SUPPLY (TWS)

TOWER WATER RETURN (TWR)

H X

1 DP

V-3

DP

V-4

(C D

W R

(TWR)

(TWS)

(C D

W S)

(C D

W S)

V-5

(C D

W R

BASIN HEAT

ELEMENT

P-3

P-4

V-2

CT

V F D

TREND

X X

X

INPUT

DI1

DI2

DI3

DI4

ANALOG

AO1

DIGITAL

DO1

DO2

DIGITAL

OUTPUT

DI6

DI9

X X

DO3

DI10

TOWER WATER SUPPLY TEMPERATURE

HX-1 DIFFERENTIAL PRESSURE (BUILDING LOOP)

TOWER WATER RETURN TEMPERATURE

TOWER BASIN TEMPERATURE

HX CONDENSER WATER LEAVING TEMPERATURE

CONDENSER WATER SUPPLY TEMPERATURE

CONDENSER WATER RETURN TEMPERATURE

AI1

AI2

AI3

AI4

AI5

AI6

AI7

X X

X

HEAT EXCHANGER DIFFERENTIAL PRESSURE

SETPOINT (FOUR REQUIRED)

OUTSIDE AIR TEMPERATURE DRY BULB

OUTSIDE AIR TEMPERATURE WET BULB

PUMP STATUS P-3

FAN SPEED STATUS CT-1

PUMP STATUS P-4

CT-1 VIBRATION STATUS

EMERGENCY SHUTDOWN

PUMP ENABLE/DISABLE P-3

PUMP ENABLE/DISABLE P-4

FAN ENABLE/DISABLE CT-1

X X X

AO1

DO3

DI5 TOWER STATUS CT-1 X

DI6

DI2

AO2

DO1

DI3

ANALOG XAO2 PUMP SPEED STATUS P-3

XAO3 PUMP SPEED STATUS P-4AO3

DO2

DI4

AI1

AI2

AI7

HX-1 DIFFERENTIAL PRESSURE (TOWER LOOP)AI8

(CDWR)

(CDWS)

AI8

AI6

T AI4

TAI3

T

T

T

X

SSF-1

DO4

DI11

DI11 FILTER STATUS SSF-1

DO4 FILTER ENABLE/DISABLE SSF-1

DI12

DI13

HIGH WATER LEVEL SWITCH

LOW WATER MAKE-UP SWITCH

DI14 LOW WATER LEVEL SWITCH

X X X

US Army Corps of Engineers ®

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