Current Detection Specifications - ABB i-bus SA/S 2.6.2.1 Product Manual

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ABB i-bus KNX
Device technology
The switching capacity specifications AC and AX are not directly comparable. However, the following
switching capacity capability can still be determined:
The lowest switching capacity corresponds with the specification
AC1 – mainly for ohmic loads.
The following switching capacity should be rated higher
AX – fluorescent lamp loads, under 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 lamp loads (200 µF).
Both specifications are almost equivalent. This means that a device which has met the test for AC3 under
EN 60 947 will most probably meet those under EN 60 669 with 200 µF.
In conclusion, generally speaking:
•
Users or customers primarily involved with industrial applications will tend to refer to AC3 switching
capacities.
•
Users 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 when selecting a Switch Actuator.
2.10

Current detection specifications

The Switch Actuators with current detection are recognizable by a number 6 as the third number 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 parameterized
separately.
For further information see:
The current recognition detects sinusoidal load currents with a 45-60 Hz frequency range. 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, producing an RMS
value. The factor 1/√2 is derived from the crest factor Û/U
44 2CDC 505 056 D0208 | SA/S
Parameter window A: Current Detection, p. 101
= √2 for a sinusoidal curve type.
rms