
6 EPHY-MESS Industrial Motor Protection REV201205052
1.3 Chip-type NWT with dot like measuring spot
1.3.1 Flexible chip-type NWT located in support structure (M-OK / AK)
Flexible chip-type NWT located in a support structure are designed for control applications, where a
punctual measurement (TSL = 2 mm) and a flexible type of NWT are required. The chip-type NWT of
the M-OK /AK design is approved for use within the ranges of increased safety.
Structure
The measuring resistor is, relieved from pressure, contained in an insulating preformed silicon body.
Using a casting compound and cover having permanent flexibility provides for an additional insulation.
For external insulation the NWT and the cable outlet are covered with PTFE shrinkable tubing. IECEx
and ATEX-approval for use in hazardous areas with protection type:
IECEx: Ex e II
ATEX: II 2G Ex e II
Fig. 4, M-OK / AK
1.3.2 Flexible chip-type NWT embedded in preformed PESU carrier ( M-OK / KS )
Due to its thickness of only 2 mm the flexible chip-type NWT embedded in a preformed PESU carrier
element is designed to extend the operative range of the punctual measuring NWT into areas which
until now could be covered only by the bifilar-type NWT. IECEx and ATEX-approval for use in
hazardous areas with protection type:
IECEx: Ex e II
ATEX: II 2G Ex e II
Structure
The measuring resistor is, relieved from pressure, embedded in and cast into a preformed PESU
carrier. Due to the excellent electric properties of the carrier material, high-tension strength, ranges
below 4 kV do not require any further insulation of the sensor.
Fig. 5, M-OK / KS
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