CEMB USA T-NC-API-ATEX - Manual (Page 3)

3
TRANSDUCER POSITIONING
Refer to dwg. 52330-C.
1) Drill holes on the machinery for the sensor mounting devices and for any cable
protection devices (sheaths, ducts etc.).
2)
Separate (unless already disconnected) the extension cable and sensor parts from the
demodulator by means of the connectors.
3)
Fasten the devices for mounting and adjusting the sensors on the machine guard. Fix
the demodulators at a distance from the machinery less than that of the sensor
connecting cables.
4)
Fit the sensors on the devices prepared in points 1 and 3.
5)
GAP adjustment is by means of the thread of the sensor or by the mounting device if
provided with adjustment (e.g. Cemb supports series SR); if the latter is not
available, the sensor can be fastened with the nuts provided as standard with each
sensors and which act as nut/locknut.
6) After checking that the machinery lies in position K (ZERO position with the
machine stationary), perform a preliminary mechanical adjustment of the GAP as
indicated in the drawing. The GAP indicated refers to the mid point of the
measuring range.
7)
Proceed to the electrical connection of the sensors to the respective demodulators
and connection of the latter to the measuring instrument as indicated in drawing
52330-C.
8)
Still with the machinery in position K and with the transducer connected and powered
up, use the sensor adjustment device to search for the exact coincidence between
the mechanical gap indicated in the application drawing and the electrical
calibration of the demodulator.
Read the voltage corresponding to the GAP on a voltmeter connected across pins
OUT and COM on the demodulator terminal board (or else across the terminals
corresponding to the transducer signal input of the measuring instrument).
As the GAP given (indicated in dwg. 52330-C and set approximately in point 6) refers
to mid-point of the measurement range, on the scale -2 to -18 Vdc of the measurement
range (-2Vdc=start of scale ≡ 0.5 mm, -18Vdc=full scale ≡ 2.5 mm), a reading of – 10
Vdc should corresponding to the mid point condition.
Hence the sensor position should be adjusted through small displacements along its
longitudinal axis until -10 Vdc is read on the voltmeter.
9) Lock the sensors in position, tighten any cable glands, close any cable protections,
the demodulator box, etc.
REMARKS REGARDING CORRECT POSITIONING OF TRANSDUCERS T-NC
1) Never, under any circumstances, modify the sensor / converter cable length: this
would cause a measuring error.
2) The end part of the sensor must lie at a distance from metal materials different
from the one involved in measuring the distance: at least twice the max. amplitude
of measurement (see application drawing).
3) When mounting the sensor, a reference cone should be prepared at 90° vertex from
the sensor tip. No metallic material must be introduced in the cone apart from the
surface to be measured.
Notes concerning certification:
1)
The use of ATEX certified transducers is not allowed for different hazardous
conditions or for those exceeding the data specified on the nameplate
affixed to the transducer.
2)
The transducer does not require maintenance. Any work regarding performance
checks or repair should only be carried out in a laboratory duly authorized
by CEMB SpA.