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EC stands Electronically Commutated (EC). EC fans are controlled using 0-10Vdc control signal. The main benefits of using the EC fans are increased efficiency reducing energy consumption, accurate speed control for better energy comfort, longer lifespan as no carbon brushes are used and compact size.
EC fans are controlled using 0-10Vdc control signal. The TCR/QCR controllers have up to 4 x 0-10Vdc outputs. Any of these outputs can be configured to send the control signal to the EC Fans. The diagram below illustrates this.
In a typical application the EC Fan speed is controlled by increasing the fan speed when there is more demand. In the above 4-pipe FCU application the EC Fan Speed is increased when there is either heating or cooling demand. In other words when the heating or cooling valve opens the EC Fan is switched on to push the air through the FCU to the room space.
By default the EC Fan Speed follows the profile in the picture below. When there is demand on the Fan Source (=heating or cooling valve opens), the Fan Demand output is switched to the Minimum Fan Speed. When the Cooling or Heating Valve continues to open the Fan Speed is increased according to the diagram below. So, for example, when the. heating valve is fully open the fan is running at full speed.
ADDITIONAL FUNCTIONS
The TCR/QCR controllers provide additional functions for better and more energy efficient control.
Start-Up Fan Boost
When the fan starts, on the TCR/QCR controller it is possible to configure the fan to initially to go a pre-defined level for the pre-defined period after which the fan speed is controlled by the demand (heating/cooling valve position). This way the inertia needed, to get bigger EC fans rotating is overcome. The Fan Minimum Speed can then be reduced offering energy savings. On the TCR/QCR controllers the initial fan speed is set by 742 - Fan_Speed_1 parameter. The time that the fan runs at the initial fan speed is set by 748 - Fan Startup Delay.
Fan Off Delay
When there is no longer demand for the heating or cooling, the fan can be switched off (fan demand/output goes to 0V switching the EC Fan off). With TCR/QCR controllers the switch-off can be delayed by 746 - Fan Off Delay. By setting the delay time to e.g. 30 seconds allows the controller to remove residual heat from the heating coil providing energy efficiency when the room is controlled to the setpoint temperature, or in case of cooling prevent condensation by removing the cold energy from the cooling coil.
Fan Curve and Maximum Speed
By default the TCR/QCR Fan speed control signal operates linearly from minimum speed to the full speed based on the demand. In some cases the maximum fan speed needs to be limited (e.g. for noise considerations). In this case if 744 Fan_Speed_3 is set less to 100% e.g. if set to 85%, the fan output is limited to 85% (=8.5V).
Furthermore it is possible to adjust the fan speed curve. Typically in the last 15-20% of the fan curve, the air volume will not increase as much as for lower fan levels, so the TCR/QCR curve can be adjusted to ensure linear, more optimal, fan performance.
The diagram below illustrates the Maximum Fan Speed Setting and Logarithmic Fan Curve setting.
