Rockwell Automation FANM FanMaster Energy Saving Package - Manual (Page 10)

1-4 FanMaster Overview
Allen-Bradley® FanMaster™ Energy Saving Package Installation Manual - Publication FANM-IN001B-EN-P – December, 2009 PN-65329
Fan Starter Current Sensor
This device is used only when FanMaster is installed in evaluation mode.
The current sensor device is designed such that one wire lead of the existing
fan motor passes through its center. The current sensor has a switch that
actuates when it senses current flow in the motor wire, indicating that the
fan motor has been started by the existing control system. The actuated
switch identifies when the HVAC unit fan normally runs so the FanMaster
calculator can take into account the HVAC normal hours of operation and
more accurately project monthly cumulative savings.
Fan Starter Hard-Wired Interconnection
This device is used only when FanMaster is installed with a drive.
FanMaster requires a start signal from the existing BAS system in order to
know when to start and stop the fan. The control signal on the coil of the
existing fan motor starter provides this signal. The starter coil signal is
typically 115V AC or 26V AC. Two interposing relays, one that
accommodates each of these voltages, are shipped with FanMaster (120V
AC relay already installed at position CR4). Other control voltage relays are
available from Rockwell Automation.
FanMaster Operation Fan Speed Reduction
With the installation of FanMaster, the existing HVAC control system
continues to maintain room temperature by monitoring its own temperature
sensors and controlling the heating and cooling elements. FanMaster
provides new, independent temperature sensors mounted in the airflow of
the HVAC unit. These sensors allow FanMaster to determine if the existing
controls are requesting heating and cooling and to adjust the fan speed to a
value appropriate for the amount of heating and cooling required.
As the existing controls call for more heating or cooling (as determined by
the amplitude of the temperature differential measured before and after the
heating and cooling elements), FanMaster responds by increasing the fan
speed. As the amount of heating or cooling required decreases, the
temperature differential decreases and so does the FanMaster fan speed. If
the existing controls are not calling for heating or cooling, then there is no
temperature differential across the heating and cooling elements and
FanMaster reduces the fan speed to a user specified minimum speed.
Reducing the HVAC unit’s fan speed when not calling for maximum heating
or cooling results in significant savings in the energy required to run the fan,
according to the Law of Affinity.