Air Cooled Liquid Chillers - Page 33

Leaving Solution Reset

This flexible option allows active leaving solution reset based on customer selectable inputs from the zone, entering solution temperature  or outside air temperature. When the application is sensitive to one of these parameters, subcooling of critical zones is prevented.

External Leaving Solution Setpoint

Remote setpoint potentiometer can be ordered to allow adjustment of the leaving solution setpoint remotely.

Generic Building Automation System Module (GBAS)

Two Generic Building Automation System Modules (GBAS) are available as an option to provide broad control capabilities for building automation systems, other than the Trane’s Tracer^® system.

The 0-5 vdc input GBAS Module contains 4 analog inputs, one binary input for demand limit, and 5 binary outputs.

The 4 Analog inputs can accept a 0- 5 vdc or a three wire potentiometer signal and be assigned to:

1. Leaving Solution Setpoint

2. Ice Build Terminate Setpoint

3. Hot Start Load Limit Setpoint

4. Maximum Capacity Level Setpoint

• The 5 Binary Outputs can be assigned:

1. Active Unit Diagnostics
2. Compressor running status
3. Maximum Capacity (all compressors running)

    4,5. Open - Diagnostics can be grouped or individually assigned by the user and may             be placed in these outputs.

The 0-10 vdc input GBAS module contains 4 analog inputs, one binary input for demand limit, four analog outputs and one binary output.

• The 4 analog inputs can accept a 0- 10 vdc signal and be assigned to:

1. Leaving Solution Setpoint
2. Ice Build Terminate Setpoint
3. Hot Start Load Limit Setpoint
4. Maximum Capacity Level Setpoint

• The 4 analog outputs can be assigned to:

1. Leaving Solution Temperature
2. Entering Solution Temperature
3. Saturated Condenser Temp. Ckt 1, 2
4. Evaporator Temp. Ckt 1, 2
5. Liquid Line Pressure Ckt1, 2
6. Suction Pressure Ckt 1, 2
7. Actual Capacity Level
8. Outdoor Air Temperature

• One Binary output can be assigned to:

1. Active Unit Diagnostics
2. Compressors Running Status
3. Max Capacity

Hot Gas Bypass (HGBP)

The HGBP control allows unit operation below the minimum step of unloading. Hot gas bypass is initiated when the last capacity step is running and the capacity control algorithm generates a subtract command. HGBP remains energized until the load increases, the chiller freeze protection function is activated, a user defined run time has expired, the low pressure control is open, or the unit goes into ice building mode.

Alarm and Max Capacity Relay

These features are user selectable and are mutually exclusive of each other. If the alarm relay output is selected, it will provide a way to trigger a field supplied alarm whenever the UCM detects a fault requiring manual reset. The customer can assign which fault modes will trigger the alarm relay. The alarm will deenergize when the manual reset is cleared. When Max Capacity Output is selected, it will trigger a field installed device indicating the unit has reached its maximum cooling stage; this gives the customer the ability to turn on auxiliary systems to manage comfort.

Ice Building Control

A contact closure on the UCM allows either a field installed device or an ICS system to initiate the unit to operate in the ice building mode. In this mode normal chiller temperature control is bypassed and the unit runs fully loaded until ice building is complete. There are two optional ice building modes that can be selected through the HI. Ice building is terminated when the customer provide contacts are opened, Ice Building Stop is initiated from the Tracer, or the entering solution temperature reaches or drops below the ice building terminate setpoint.

When the entering solution temperature reaches the terminatesetpoint,the unit will go through pumpdown if enabled and remain in Ice.Complete standby mode until the ice build mode is terminated.

• Option 1 - One time Ice building mode allows the unit to run fully loaded until the entering solution temperature falls to the active ice building terminate setpoint (IBTS) When the entering solution temperature reaches the terminate setpoint (IBTS).
• Option 2 - Continuous ice build mode allows the unit to run fully loaded until the entering solution temperature falls to the active ice building terminate setpoint (IBTS). When the entering solution temperature reaches the terminate setpoint, the unit will go through pumpdown if enabled, and remain in Ice build delay. The unit will remain in ice build stand-by until the ice build timer expires. The unit will then start the pump and wait for the loop stabilization timer to expire. The unit will run fully loaded until the entering solution temperature falls below the ice build termination setpoint. The unit will continue cycling through these ice building states until the Ice build mode is terminated or changed to option 1.