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Design
The electronic wiring and the flag indication is incorporated in the
housing of the short circuit indicator. The stainless steel frame fixes
the reading instrument on the core. It is possible to disconnect the
frame from the housing. When the reading instrument is in its final
position on the core, one or two fixing screws on the frame save this
postion.
For bigger diameters of the core, the frame must be turned up.
Therefore, two bending positions are marked on the frame.
The indicator has a high resistance to atmospheric conditions, for this
reason the flag indication and the electronic wiring are absolutly
sealed.
Function
The
short circuit indicator has to be mounted on high-voltage cables.
In case of a short circuit, a coil in the sensor will detect the peak
current impulse.
If the pre-adjusted operating point is reached, the
evaluation-electronics will stimulate the flag indicator.
A "red
surface" is the signal for a detected short circuit.
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With the indicator type K, the
nescessary power for auto reset
will be gained from the electrical field, which is around the high voltage core. This unidirectional power charges a capacitor.
The capacitor becomes
discharged over an arrestor and
the reset coil of the indicator. After
the reset, the indicator
shows a black face. The approximate charging time, i.e. the reset time, is shown in the
diagramme on the right hand. The charging time of the capacitor depends on the
local situation.
The short circuit indicator type K can be provided with a multiple
adjustment for trip currents.
With the indicator type KH, the indication flag will be reset with
the
help of a magnetic system. Via a test button, a magnet is being moved,
which will then cause the indication flag to reset.
The short circuit indicator type KM resets automatically and manually.
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Assembling
The
short circuit indicator is fixed on the high voltage cable with the
stainless steel frame. For mounting, the frame must be disconnected
from the housing. After the frame has been laid around the cable, it
must be screwed on the sensor housing again. There are one or two
screws on the frame for fixing the sensor in its final position.
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| Technical Data |
| dimensions
of the sensor housing: |
short
circuit indicator type K / KH / KM ( W*H*D ) 40 * 50 * 38 mm
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| operating
current: 150 ....1500 A |
precision: +
/ - 10 %
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| temperature
range: - 40 to + 70° C |
| material
of fixing frame: stainless steel |
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