Black Box CRDX-W-FS-24KW Independent Fan Speed Control, Variance from Average Fan Speed Control

Chapter 4: E2 Controller

4.4.4.1 Independent Fan Speed Control

The system controller may be configured for independent, variable fan speed control for managing upper, middle, and lower zone cooling. The controller continually monitors the actual cold aisle supply air conditions for each fan zone (upper, middle, and lower) as determined by temperature sensors mounted locally to each zone inside the Cold Row cabinet, and it adjusts the speed of each fan to meet the supply air temperature setpoint for that zone. The operator may select from three independent fan speed temperature control methods in the Control> Set>Fan Control menu loop (Section 4.5.4.1). Minimum and maximum fan speed settings for each fan are user adjustable in the Service>Blower>Temp Zone Set Up menu loop (see Section 4.5.5.4). The fans will not run at speeds outside of the envelope established in that menu loop.

4.4.4.2 Variance from Average Fan Speed Control

When configured for variance from average fan speed control, each fan operates independently. The controller manages the speed of each fan by comparing the variance of the fan’s local zone temperature sensor to the overall average temperature measured by the sensors for all three fan zones. The controller adjusts the speed of each fan as necessary to meet the supply air temperature setpoint for that zone.

4.4.4.3 Temperature Proportionate Speed Control

The controller adjusts the speed of each fan proportionally for that zone to meet the supply air temperature setpoint. The controller compares the variance of each temperature zone to the temperature setpoint and develops a proportional control output to modulate the speed of each fan to meet the supply air temperature setpoint for that zone.

4.4.4.4 Manual Speed Control

The controller continually controls the speed of each fan to values manually entered in the system controller Control>Set>Fan Control menu loop (Section 4.5.4.1) without regard to the temperature setpoint.

4.4.5 Remote On/Off

For Remote On/Off operation, terminal positions are provided to connect a remotely located, On/Off switching control device. If the A/C unit is turned on and the E2 controller receives a remote input signal to turn off the A/C unit, the controller disables all control outputs and a message “Off by Remote Shutdown” appears in the main display screen. The A/C system will automatically be reenabled when the remote On/Off signal calls for the A/C unit to turn back on.

The control device may be an On/Off switch, thermostat, or a humidistat. If customer provided, the remote On/Off control contacts must be sized appropriately. The Remote On/Off contacts must have a minimal rating of 24 VAC. Refer to the electrical drawing included with the A/C unit for the electrical specifications and for wiring details.

4.5Menu Screens 4.5.1 Main Menu

Figure 4-21. Main menu.

The Main Menu is accessed from the Main screen by pressing the key. The Main Menu screen provides a complete listing of the menu loops that are available. You may scroll through the menu categories using the Up and Down arrow keys. From the Main Menu screen, you may select from among the following standard menus:

“Info” displays basic read-only status information. Allows you to monitor system operational parameters. No password is needed at this level.

“Alarm Log” displays all alarms and “power-ups” in sequential order with a time and date stamp. No password is needed at this level.

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