CEMB USA T-NC-30-S User Manual

1

T-NC/30-S NO CONTACT TRANSDUCER

FUNCTION

Transducer T-NC/30/S is used for performing the following measurements:
DIFFERENTIAL EXPANSION (ex.Turbine), i.e. relative movement between the rotor and the
machine casing; the measurement is made by mounting the sensor integral with the
machinery casing in the spot corresponding to the thrust block of known characteristics
prepared on the rotor. The picked up signal should be sent to the CEMB T2 unit for
processing.
AXIAL POSITION, (ex. Turbine Shaft Position with respect to the Thrust Bearing), the
measurement is made by mounting the sensor of each transducer on the machinery casing,
axially facing a block either mounted or obtained on the rotor close to the thrust
bearing, in order to measure the wear on the bearing. The signals picked up should be
sent of the CEMB T3 units for processing.
ECCENTRICITY, (ex.Turbine Shaft), the measurement is made by mounting the sensor of the
transducer on the machinery casing, radially facing a ring mounted or obtained on the
rotor, in order to measure the eccentricity of the rotor at low speed; the signal
picked up should be sent of the CEMB T4 unit for processing.

COMPOSITION

The transducer consists of a field-mounted sensor T-NC/30 and converter box T-NC/S
outside the machinery.

CEMB S.p.a.

Costruzioni Elettro Meccaniche ing. Buzzi & C. S.p.a.

Sede legale: Via Risorgimento, 9
23826 MANDELLO DEL LARIO - (Lecco) ITALY

Cap. Società ? 1.500.000 i.v.
Reg. Impr. Lecco 00221870132
C.C.I.A.A. Lecco REA 75997
Meccanografico LC 000078
C.F. 00221870132 -P.IVA IT 00221870132

Telefono +39 – 0341.706.111

Industry Div. Fax +39 – 0341.735.678

Garage Div. Fax +39 – 0341.700.725

www.cemb.com

Vibration Analysis Div. Fax +39 – 0341.706.299

Cap. Società ? 1.500.000 i.v.
Reg. Impr. Lecco 00221870132
C.C.I.A.A. Lecco REA 75997
Meccanografico LC 000078
C.F. 00221870132 -P.IVA IT 00221870132

Telefono +39 – 0341.706.111

Industry Div. Fax +39 – 0341.735.678

Garage Div. Fax +39 – 0341.700.725

www.cemb.com

e-mail: [e-mail]

Vibration Analysis Div. Fax +39 – 0341.706.299

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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 invested by such RF field, an eddy
current is generated on it. The energy required to generate such eddy current (which is
proportional to the distance between the reference surface and the sensor surface)
reduces, in proportion, the energy present in sensor. Such difference is then detected
by the converter.
The converter amplifies and processes this signal thus supplying a d.c. output voltage
proportional to the distance under consideration.

TECHNICAL CHARACTERISTICS

Composition : sensor, converter

Type of measurement : differential

Range of measurement : ± 6,5 mm

Range of application : Temperature (Sensor) = -20°C to +175°C
Temperature (Converter) = -10°C to +70°C
Humidity (Sensor) = max 100%
Humidity (Converter) = max95% with condens
Ambient (Sensor) = IP67 EN 60529/10.91
Ambient (Converter) = IP65 EN 60529/10.91

Sensitivity : 0.77 V/mm

Power supply : + 15÷24 Vdc; GND.

Connection : Connector MIL C-5015, series 3102/16, standard kit

Convert. casing material : Die-cast aluminium

Sensor casing material : Stainless steel

Weight of the converter : ~ 0.7 Kg

Weight of the sensor : ~ 0.5 Kg

Maintenance : None

Drawings enclosed : 19457 = Overall dimensions, mounting, connections.

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4

TRANSDUCER POSITIONING

Refer to drawing Nr. 19457

1) Drill holes on the machinery for the sensor support and for any cable protection
devices (sheaths, ducts etc.).

2) Drill a hole to fasten the converter box at a distance from the machinery shorter

than that of the connecting cable (5m).

3) Separate the sensor from the converter by disconnecting the cable from the terminal

board inside the converter (carefully note the polarity of the two leads making up
the cable), then mount the sensor on the support prepared in point 1

4) After checking that the machinery lies in position K (ZERO position with the

machine stationary), perform a preliminary mechanical adjustment of the GAP by
acting on the nut-lock nut device of the sensor. The GAP indicated in the
application drawing refers to the mid point of the measuring range of the
transducer. In the case of frontal measurement of the displacement, the mid point of
the measurement range of the sensor corresponds also to the mid point of the
measurement to be made. If the measurement is longitudinal (sliding of an inclined
block) instead of frontal, proceed to calculate the GAP corresponding to the
position K of the machinery, taking due consideration of the measuring range and
angle of inclination of the block.

5) Fasten the converter box using the holes drilled in point 2 and attach any

protective sheaths if necessary. Reconnect the sensor cable to the converter
terminal board making sure of the exact polarity of the leads making up the cable.

6) Proceed to the electrical connection of the converter with the measuring

instrument.

7) The following instructions refer to the machinery under the supply, which requires
longitudinal measurement (inclined block) of the expansion, according to the data
given in the above-mentioned table attached to this section; otherwise adapt the
data to the plant characteristics.

With the machine in position K and with the measuring instrument operating, use
the nut-lock nut device of the sensor to search for the exact coincidence between
the mechanical gap and the electrical calibration of the converter in one or,
better, both of the following ways:

- reading on a voltmeter connected across pins A and D of the converter connector

(or else across the terminals corresponding to the transducer signal input on
the terminal board of the instrument) on the scale 0 to 10 Vdc of the range of
measurement (0Vdc= scale start, 10Vdc=full scale) of the volts corresponding
to the Gap; as the Gap indicated in the application drawing of the transducers
refers to the mid point of the range of measurement, under this condition there
should be a corresponding reading of 5 Vdc.
Hence the sensor position should be adjusted through small displacements along its
longitudinal axis until the value of 5 Vdc on the voltmeter.

8) Then lock the sensor in position using the nut-lock nut device.

9) Close the converter making sure that it is spray- and dust-proof.

REMARKS REGARDING CORRECT POSITIONING OF TRANSDUCERS T-NC/S

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.

UTS051024

ASTD58120