CEMB S.p.A. - 23826 MANDELLO DEL LARIO (LC) - Via Risorgimento 9
Tel. (+39)0341/706.111 - Fax (+39)0341/706.299
www.cemb.com e-mail: stm@cemb.com
No contact transducer T-NC/API
Certified to Directive ATEX 94/9/CE
FUNCTION
The T-NC/API transducer makes the static or dynamic measurement of the distance of a
ferrous material from the transducer sensor according to the principle of eddy
currents. Hence it is possible to measure the following quantities: vibrations,
expansion, axial displacements, eccentricity, speed of rotation.
The output signal should be processed subsequently in a safe zone by a measuring
channel of the “T” series.
The transducer is certified for applications in areas classified as:
- Ex II 1 G Ex ia IIC T5 Ga
- Ex II 1 G Ex ia IIC T6 Ga
1
PRINCIPLE OF OPERATION
The T-NC system generates a radio frequency field, which is radiated by the sensor
surface.
When the reference surface facing the sensor is impinged by such RF field, an eddy
current is generated on this surface. The energy required to generate this eddy current
(which is proportional to the distance between the reference surface and the surface of
the sensor), is reduced in proportion to that involved in the sensor; such difference
is picked up by the converter.
The converter amplifies and processes such signal by supplying, for the processing, a
d.c. output voltage proportional to the distance under examination.
COMPOSITION
Each transducer basically consists of a field sensor, an extension cable which can be
integral with the sensor or unpluggable from it through an intermediate connector, and
a demodulator, likewise unpluggable from the extension cable or sensor cable, which
transforms the picked up signal in a voltage suitable for processing.
TECHNICAL CHARACTERISTICS OF EACH SENSOR-DEMODULATOR CHAIN
Basic composition : sensor, extension cable, demodulator
Type of measurement : differential
Dynamic range : frequency 0 to 10,000 Hz
amplitude max 2 mm (from 0.5 mm to 2.50 mm)
Linearity over the entire
range of measurement,
within the operating temperature limits indicated : ± 1%
Rated scale factor : 200 mV/mil (7,87 mV/µm)
Sensitivity to temperature : according to API 670
Power supply : -18 -24 Vdc; GND
Operating range : . temperature (sensor) = -35 to +175° C
. temperature (convert) = -20 to +80°C
. humidity (sensor) = max 100%
. humidity (converter) = max 95% not condensing
. ambient (sensor) = IP67 EN 60529/10.91
. ambient (converter) = IP65 EN 60529/10.91
Connection : . miniaturized coaxial connector
(sensor / converter)
. screw terminal board model 476-CS/AL/3
(converter / instrument)
Weight of converter : approx. 0.30 Kg
Weight of one sensor : approx. 0.10 Kg
Maintenance : None
Drawings enclosed : 52330-C = Dimensions-mounting-connections
2
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.
3
Equipment intended for use in areas in which
explosive atmospheres caused by mixtures of
s or air/dust
mixtures, are present continuously,
frequently or for long periods, very high
Suitable for substances (gases) of group IIC,
•
Certifications to ATEX 94/9/CE
0722 II 1G Ex ia IIC T5orT6 Ga
CESI 03 ATEX 094
Legend of nameplate safety data
0722
II
1
G Protection for Gases, Vapours, Mists
Ex ia
II C
T5
T6
CESI 03 ATEX
094
Ta
Marking of conformity with the applicable
European directives
Number of the Notified Body carrying out the
surveillance (CESI)
Marking of conformity with Directive 94/9/CE
and relative technical standards
Equipment suitable for surface applications
(not for mining)
air and gases, vapours, mist
level of protection.
Suitable for Zone 0
Equipment belonging to category "ia" with
intrinsic safety for Zone 0
also suitable for groups IIA and IIB
Temperature class T5 (surface temperature
100°C)
Temperature class T6 (surface temperature
85°C)
Certificate identification:
• Name of the laboratory issuing the CE-
type-examination certificate
• 03 = year of issuing the certificate
094 = number of the certificate
Ambient temperature -20 to +80 °C (T5 class)
Ambient temperature -20 to +60 °C (T6 class)
4
T-NC/API-ATEX 02 gb
5
ASTD88220
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