ABB SA/S 12.16.6.1 Product Manual - Knx Device
ABB i-bus
®
KNX Device
technology
SA/S | 2CDC 505 056 D0207 37
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.
2.9
Current detection
specifications
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
, page 94
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
rms
=
√2 for a sinusoidal curve type.