Measurement Methods; Requesting Status Values And Setting The Cycle Times - ABB i-bus KNX Product Manual

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ABB i-bus KNX
Device technology
2.4

Measurement methods

The Energy Actuator has its own evaluation electronics for detection and measurement of the various
measured variables for each output, which can be programmed separately.
Current and voltage are measured directly; all other variables (meter values, active power, apparent pow-
er, power factor, crest factor, frequency) are derived from these values.
The measurement method, other than with the Switch Actuators SA/S, is a real RMS value measurement.
The signal is scanned 100 times per period (at 50 Hz), and the RMS value is determined from these
scanned values. The measuring accuracy is also assured with non-sinusoidal signals.
The measured values are evaluated every 200 ms. Provided that the parameter Delay for switching has
been set to the value 0, exceeding the threshold, for example, will be detected after 200 ms at the latest.
Current values less than 25 mA are displayed as value 0 (starting current). For this reason, even values
derived from the current are indicated as a value of 0 even when a current less than 25 mA is flowing.
Voltages less than 5 V as shown as 0 for technical reasons.
Note
The progression of the current and voltage curves is not analyzed, i.e., analysis of the signal waveform
(e.g. FFT) is not undertaken. All values are determined by sampling the signal.
Therefore, the power factor always results as the sum of the distortion power (e.g. dimmer currents) and
displacement power (e.g. inductive or capacitive loads). This power factor does not (or only in special
cases) comply with the cos φ (Cosine Phi ) with a phase displaced current!
It can also not be used for reactive power compensation!
2.5

Requesting status values and setting the cycle times

The 1 bit communication objects for requesting status values are enabled for the Energy Actuator at a cen-
tral point. There is a 1 bit communication object each for requesting all status values, all meter values, all
power values and all instrument values.
Furthermore, the cycle times for cyclic sending of telegrams are set at a central point with the Energy Ac-
tuator. There is a common cycle time for cyclic sending of all power values, all instrument values and all
meter values.
On the individual communication objects, you can then set whether the value of the respective communi-
cation object should or should not be sent cyclically or on request.
16 2CDC 505 084 D0203 | SE/S 3.16.1