Danfoss ECL Comfort 310 Operating Manual page 17

Operating Guide
PWM (Pulse Width Modulation)
A 200 Hz frequency is applied to the PWM controlled pump. The
duty cycle (the percentage of the period time) determines the
pump speed.
Pump speed, PWM or 0 – 10 Volt controlled
Some types of speed controlled pumps are limited to a minimum
speed, for example 30 % (PWM or 3.0 Volt). Even if the applied
control % gets lower than 30 %, the pump speed remains on the
minimum level *.
Furthermore, when the applied control % gets below, for example,
10 %, the pump switches OFF. In order to get the pump switched
ON again, the applied control % must exceed 20 %.
This behavior can, at low load or a too big pump, cause unstable
temperature regulation. To avoid this, the P318 has a function
where the applied control signal is converted into a pulsed signal.
The pump is shortly stopped and then started again. The result is a
pump speed control also below the minimum speed level.
The parameters "PWM period" (ID 11565) and "Adapt time" (ID
11065) are used for this functionality.
*) See the pump manufacturer's data sheet
Input configuration
Inputs (as from S7 and up) which are not part of the application can
be configured to be Pt 1000, 0 - 10 Volt, frequency (pulse counter)
or Digital input. This feature makes it possible to communicate
extra signals, such as temperatures, pressures, ON / OFF conditions,
via Modbus and ECL Portal.
The configuration is done by means of the ECL Tool (free software
for download) or directly in a dedicated menu in the ECL Portal or
the connection for Modbus (BMS / SCADA).
Commissioning
When the P318 has been uploaded the ECL Comfort 310 controller
starts in Manual mode. This can be used to verify the controlled
components for correct functionality.
Depending on system type, it is recommended to change some
factory settings individually in order to optimize the functionality.
These setting changes, if required, are listed below the system
types in the section 'Identifying the system type'.
The application key must be inserted in order to change settings.
Danfoss District Energy
ECL Comfort 310, application P318
The controller is pre-programmed with factory settings that are shown
in the 'Parameter ID overview' appendix.
VI.JM.Q3.02
DEN-SMT/DK 17