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724-746-5500 | blackbox.com
Page 18
724-746-5500 | blackbox.com
Chapter 1: Introduction
During startup, the fans begin operating in stages with five-second time delays. The middle fan starts first, then the upper fan,
then the lower fan. The system controller monitors fan operation. If one or two of the fans fails to operate, the controller alerts
the operator with an alarm message and increases the speed of the remaining fan(s) to compensate for the loss of airflow.
Use the system controller to configure the fans for zone temperature control with independently variable fan speeds or with all
three fans operating at the same variable speed (See Section 4.4.4).
1.5.7 Temperature/Humidity Sensors
Control and alarm recognition takes place by means of the controller analyzing signal inputs from the sensors to manage the
operation of the A/C unit consistent with the setpoints entered in the system controller. The system controller monitors three
NTC-type temperature sensors and a 4–20 mA temperature/humidity (T/H) sensor.
The NTC sensors are factory installed in predetermined supply air fan zones inside the cabinet. Each NTC sensor is used by the sys-
tem controller to manage the speed of the fan for that zone to meet the supply air setpoint temperature. The return air is moni-
tored by a temperature/humidity (T/H) sensor that is typically mounted inside the cabinet. As an option, you can remove the
return air T/H sensor from the cabinet and mount it in the hot aisle. View the actual sensor values from the controller user
interface display using the Information menu loop.
1.6 Optional Equipment
1.6.1 Remote Mounted Supply Temperature/Humidity Sensor
As an option, a supply T/H sensor may be provided for field installation (see Section 2.6.2). This is to be mounted in the supply
(cold aisle) space for monitoring or control purposes. Refer to the electrical drawing supplied with your unit for wiring details
specific to your system.
1.6.2 Water Detector
As an option, Black Box offers spot-type or strip-/cable-type water detectors (see Section 2.6.1). Upon sensing a leak, the water
detector control circuit will signal the system controller of the alarm condition. The system controller is programmed to shut down
the compressor and the fans when a leak is detected.
1.6.3 Smoke Detector
Optionally mounted in the return air side of the cabinet, a photo-electric smoke detector senses the presence of smoke and
signals the controller when a smoke alarm condition exists and shuts down the air conditioner.
1.6.4 Firestat
Optionally mounted in the return air side of the cabinet, a fire detector senses high return air temperature and signals the
controller when a fire alarm condition exists and shuts down the air conditioner.