Configuring the ECL 2000
EI.65.D4.02
30
Pulse sensors A pulse sensor is selected by setting Type to Pulse. Pulse sensors can be used for
measuring:
• Sun intensity
• Wind velocity
• Water flow
• Energy
• “Other”.
When Type is set to Pulse, 2 more parameters can be set: Scaling and Interval.
The function of these is explained in the following.
Scaling, Interval
During a time interval, the sensor delivers a number of pulses to the controller’s
sensor input. This number of pulses must be converted into the correct value. The
parameters Scaling and Interval are used to perform this conversion.
Scaling specifies the significance of 1 pulse.
When water flow or energy is being measured, the unit of Scaling must be selected
in such a way that the maximum value measured will not exceed 1024. See, for ex-
ample, the Scaling ranges for water flow in the table on page 31: The range 1.00 –
9.99 l is equivalent to the range 0.0010 – 0.0099 m
3
. The range 0.0010 – 0.0099 m
3
must be used for sensors which may give an output value of more than 1024 l/h.
For example, if Scaling is set to 1 l, the maximum pulse frequency that can be
measured is approximately 0.25 Hz, corresponding to a measured value of:
0.25 s
-1
* 1 l * 3600 s/h = 900 l/h,
which is less than 1024 and therefore acceptable.
When measuring flow, it is important to remember that the value measured is ‘per
hour’.
The Interval parameter specifies the length of the time interval (number of sec-
onds) that will elapse between calculation of values. Selecting a short interval
causes frequent updating of the display and the regulation, whereas a longer inter-
val provides for a more stable value and greater accuracy.
The formula used by the ECL 2000 to calculate values is:
(number of pulses received) / (number of seconds elapsed).
In order to obtain a good accuracy, the ECL 2000 will measure over the specified
number of seconds and then wait for the next pulse to arrive before calculating the
value. Thus, at an Interval setting of 60 s, the accuracy is (1 s) / (60 s) = 1.6 %.
At very low pulse rates, the ECL 2000 will wait for a maximum of (4 * Interval)
before performing the calculation of the value.
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