The 8546 current monitor works with 24V DC and measures the magnetic field around a conductor (Cu-busbar).
The device switches if the magnetic field, and thus also the current passing through the busbar, exceeds a threshold value that can be set as desired.
The polarity of the DC-current makes no difference.
Due to the special technology, despite its high triggering sensitivity the device still remains functional even when encountering extremely high magnetic fields as caused by a lightning strike, for example.
The sensitivity of the device (switching threshold) can be set by means of an internal potentiometer. If the current is exceeded, a electronic switching output (positive switching with regard to 24V DC) is set.
The current monitor 8546 is applicable in a wide range of current sensoring. The lower limit is about 10A. The upper limit is dependent from the mechanical distance between busbar and sensor.
If the mechanical distance is fixed the range between the lower and upper limit for adjust the switching point is a factor of 4 (e.g. 10A-30A, or 30A-100A).
A test button in the device increases the sensitivity by a factor of 3.
In this way damage to the components can be detected at an early stage in maintenance work (advance warning failure test). Furthermore, it makes it easier to set the threshold switching point, since the test current for comparison can be lower by this factor.
The device works as a “latch”, meaning that the switching signal of the output is still present even after a brief overcurrent until the device is reset via a digital input. If this input is permanently switched, the device works as a normal overcurrent sensor (without a “latch” function.
The switching output works as “low active”, meaning that in a non-operated condition it is switched with respect to +24V DC. It switches off if the threshold current is exceeded, hence being high resistance.
A cable break is handled in exact the same wax as an overcurrent in the subsequent evaluation.
The status of the device is shown by to display LED’s:
Other design variants of coil connections, fixing, operate values and cable lead lengths on request.
Data sheet [PDF]
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