Secondary Chilled Water Pumps by gabyion

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									Secondary Chilled Water Pumps



Chilled Water Pump System - Run Conditions:
The chilled water pumps will be enabled whenever:

      They receive a request from the chiller Manager.

To prevent short cycling, the chilled water pump system will run for and be off for
minimum adjustable times (both user definable).

The pumps will run for freeze protection anytime the outside air temperature is
less than 38°F (adj.).

Chilled Water Pump Lead/Lag Operation - Three Equal Sized Pumps Running in
Parallel:
The three variable speed chilled water pumps will operate in a lead/lag fashion.

      The lead pump will run first.
      If any pump fails, the next available pump will stage on and the failed
       pump will be removed from operation.
      Additional pumps will stage on as required to maintain chilled water
       differential pressure.

The designated staging order (user definable) of the pumps will rotate on one of
the following conditions (user selectable):

      manually through a software switch
      if pump runtime (adj.) is exceeded
      daily
      weekly
      monthly

Alarms will be provided as follows:

      Chilled Water Pump 1
          
          o   Failure: Commanded on, but the status is off.
          o   Running in Hand: Commanded off, but the status is on.
          o   Runtime Exceeded: Status runtime exceeds a user definable limit.
          o   VFD Fault.

      Chilled Water Pump 2
          
          o   Failure: Commanded on, but the status is off.
          o   Running in Hand: Commanded off, but the status is on.
          o   Runtime Exceeded: Status runtime exceeds a user definable limit.
          o   VFD Fault.

      Chilled Water Pump 3
          
          o   Failure: Commanded on, but the status is off.
          o   Running in Hand: Commanded off, but the status is on.
          o   Runtime Exceeded: Status runtime exceeds a user definable limit.
          o   VFD Fault.

Chilled Water Differential Pressure Control:
The controller will measure the chilled water differential pressure and modulate
the three chilled water pump VFDs in sequence to maintain its chilled water
differential pressure setpoint. The following setpoints are recommended values.
All setpoints will be field adjusted during the commissioning period to meet
the requirements of actual field conditions.

The controller will modulate the chilled water pump speeds to maintain a chilled
water differential pressure of 12lbf/in2 (adj.). The VFDs minimum speed will not
drop below 20% (adj.).

The lead pump will run anytime the manager is enabled. On dropping chilled
water differential pressure, additional pumps will stage on and modulate to
maintain setpoint as follows:

      The controller will modulate the lead pump to maintain setpoint.
      If the lead pump cannot maintain setpoint and its speed rises above 90%
       (adj.), the second pump will stage on and modulate in unison with the
       lead pump.
      If both pumps cannot maintain setpoint and their speed rises above 90%
       (adj.), the third pump will stage on and modulate in unison with the other
       two pumps.

On rising chilled water differential pressure, the pumps will stage off as follows:

      If the setpoint is maintained and the speed of the three pumps drops by a
       user definable amount, the third pump will stage off.
      If the setpoint is maintained and the speed of the remaining two pumps
       drops by a user definable amount, the second enabled pump will stage off.
      The controller will continue to modulate the lead pump to maintain
       setpoint.

To prevent short cycling, there will be a user definable (adj.) delay between
stages, and each stage will have a user definable (adj.) minimum runtime.
Alarms will be provided as follows:

      High Chilled Water Differential Pressure: If the chilled water differential
       pressure is 25% (adj.) greater than setpoint.
      Low Chilled Water Differential Pressure: If the chilled water differential
       pressure is 25% (adj.) less than setpoint.

Chilled Water Pumps VFD Feedback Monitor:
The controller will monitor the chilled water pumps speed as feedback from the
variable frequency drive.

Chilled Water Temperature Monitoring:
The following temperatures will be monitored:

      Chilled water supply.
      Chilled water return.

Alarms will be provided as follows:

      High Chilled Water Supply Temp: If the chilled water supply temperature is
       greater than 55°F (adj.).
      Low Chilled Water Supply Temp: If the chilled water supply temperature is
       less than 38°F (adj.).
Chiller Manager


Chilled Water System - Chiller Manager - Run Conditions:
The chilled water system will be enabled continual.

Each chiller will run subject to its own internal safeties and controls.

Chiller Staging - Three Equal Sized Chillers Running in Parallel:
This section refers to the staging and sequencing of each chiller "train". The
sequence of operation for each individual chiller and its associated support
equipment (such as pumps) are not included in this section.

      The controller will monitor Return Chilled Water Temperature and will
       stage the chillers on in sequence to maintain Return Chilled Water
       Temperature Setpoint 56°F (adj.).

The following setpoints are recommended values. All setpoints will be field
adjusted during the commissioning period to meet the requirements of actual
field conditions.

The lead chiller train will run anytime the chiller manager is enabled. Additional
chillers will stage on as follows. To prevent short cycling, there will be a user
definable (adj.) delay between stages, and each stage will have a user definable
(adj.) minimum runtime.

       Stage ON                                    2nd             3rd       4th
                                                  chiller        chiller    chiller
       If CHWR temp rises above a                 58°F            60°F
       setpoint* of:

       Stage OFF                                   2nd            3rd        4th
                                                  chiller        chiller    chiller
       If CHWR temp drops below setpoint          3              3
                                                      °F             °F
       by:

*Based on a percentage of the running chiller(s) combined capacity.

The chiller staging order will be user definable. The designated lead chiller (user
definable) will rotate upon one of the following conditions (user selectable):

      manually through a software switch
      if chiller runtime (adj.) is exceeded
      daily
      weekly
      monthly

Each chiller will run subject to its own internal safeties and controls. On failure of
any chiller, the failed chiller will be "removed" from operation and the next
available piece of equipment as defined by the user will be staged on in its place.

Alarms will be provided as follows:

      Chiller 1 Failure: Commanded on, but the status is off.
      Chiller 2 Failure: Commanded on, but the status is off.
      Chiller 3 Failure: Commanded on, but the status is off.
      High Main Chilled Water Supply Temp: If the main chilled water supply
                                  56
       temperature is greater    °F (adj.).
      Low Main Chilled Water Supply Temp: If the main chilled water supply
                                       38
       temperature is less than    °F (adj.).
      High Main Chilled Water Return Temp: If the main chilled water return
                                            68
       temperature is greater than    °F (adj.).
      Low Main Chilled Water Return Temp: If the main chilled water return
                                       47
       temperature is less than             °F (adj.).
Chiller

Chiller - Run Conditions:
The chiller will be enabled to run whenever:

      Indexed to run from the Chiller manager

To prevent short cycling, the chiller will run for and be off for minimum adjustable
times (both user definable), unless shutdown on safeties.

The chiller will run subject to its own internal safeties and controls.

      Chilled Water Isolation Valve:
       The valve is hardwired to open anytime the chiller is called to run and
       will close only after the chiller is disabled.

Chilled Water Temperature Monitoring:
The following temperatures will be monitored:

      Chilled water supply.
      Chilled water return.

Alarms will be provided as follows:

      High Chilled Water Supply Temp: If the chilled water supply temperature is
       greater than 55°F (adj.).
      Low Chilled Water Supply Temp: If the chilled water supply temperature is
       less than 38°F (adj.).
Primary Chilled Water Pumps

Primary Chilled Water Pump Lead/Standby Operation:
The chilled water pumps will run anytime the chiller is called to run. The chilled
water pump will also run for freeze protection whenever the outside air
temperature is less than a user definable setpoint (adj.).

The lead pump will start prior to the chiller being enabled and will stop only after
the chiller is disabled. The pump(s) will therefore have:

      A user adjustable delay on start.
      AND a user adjustable delay on stop.

The delay times will be set appropriately to allow for orderly chilled water system
start-up, shutdown and sequencing.

The pumps will operate in a lead/standby fashion.

      The lead pump will run first.
      On failure of the lead pump, the standby pump will run and the lead pump
       will turn off.

The designated lead pump will rotate upon one of the following conditions (user
selectable):

      manually through a software switch
      if pump runtime (adj.) is exceeded
      daily
      weekly
      monthly

Alarms will be provided as follows:

      Chilled Water Pump 1
          
          o   Failure: Commanded on, but the status is off.
          o   Running in Hand: Commanded off, but the status is on.
          o   Runtime Exceeded: Status runtime exceeds a user definable limit.

      Chilled Water Pump 2
          
          o   Failure: Commanded on, but the status is off.
          o   Running in Hand: Commanded off, but the status is on.
          o   Runtime Exceeded: Status runtime exceeds a user definable limit.
   Chilled Water Pump 3
       
       o   Failure: Commanded on, but the status is off.
       o   Running in Hand: Commanded off, but the status is on.
       o   Runtime Exceeded: Status runtime exceeds a user definable limit.

								
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