Current Detection Specifications - ABB SA/S 12.16.6.1 Product Manual

®
ABB i-bus KNX
2.9 Current detection
specifications
Device technology
The switching capacity specifications AC and AX are not directly
comparable. However, the following switching capacity quality can still be
determined:
The lowest switching capacity corresponds with the specification
AC1 - mainly for resistive loads.
The following switching capacity should be rated higher
AX - fluorescent lighting load to the standard:
70 μF (6 A), 140 μF (10 A,16 A).
The highest switching capacity is designated by
AC3 - motor loads,
C-Load - fluorescent lighting loads (200 μF).
Both specifications are almost equivalent. This means that a device which
has fulfilled the test for AC3 to EN 60947 will most probably fulfil the tests to
EN 60669 with 200 μF.
In conclusion, the following can be said:
Users or customers, who are primarily involved with industrial

applications, will refer to AC3 switching capacities.
Users, who are involved with building or lighting technology, will more

often than not refer to an AX switching capacity or C-load (200 μF
loads).
The switching capacity differences must be considered with the selection of
a Switch Actuator.
The Switch Actuators with current detection are recognisable by a number 6
on the third position of the type designation, e.g. SA/S 2.16.6.1.
This is a Switch Actuator with integrated load current detection.
Each output features its own current detection with evaluation electronics,
which can be parameterised separately.
For further information see: Parameter window
The current recognition detects sinusoidal load currents with a frequency
range from 45 Hz to 60 Hz. The measured load currents are available as
RMS values. Non-sinusoidal currents, e.g. phase angle varied or distorted
currents, cause a measurement error depending on the curve type. If a DC
current is superimposed, the measurement error is again considerably
larger. Phase angle varied currents are generated, for example, by a current
rectifier.
The current detection principle in the Switch Actuator is based on the
conversion of sinusoidal load currents by a transformer. On the secondary
side of the transformer, the transferred value is rectified and smoothed by an
RC element. The resulting value is multiplied with the fixed factor 1/√ 2 that
results in an RMS value. The factor 1/√ 2 results from the crest factor Û/U
√ 2 for a sinusoidal curve type.
A: Current Detection, page 94
SA/S | 2CDC 505 056 D0207 37
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rms