CEMB USA TR-NC8 ATEX User Manual

CEMB S.p.A. - 23826 MANDELLO DEL LARIO (LC) I - Via Risorgimento 9

Tel. [phone] - Telefax (+39)0341/706.299

www.cemb.com e-mail: [e-mail]

No contact transmitter TR-NC/8

Certified to Directive ATEX 94/9/CE

FUNCTION

The TR-NC/8 transmitter makes the following measurements:

- VB: Vibration (relative) of a rotor respect to its support

- AX: Displacement (axial) of a surface with respect to a fixed point, differential

displacement between two points.

- PH: Phase reference
The measurement is made by the correct positioning of a no contact sensor in the
vicinity of the point to be measured (made of ferrous material); the transmitter
supplies an output signal suitable for an acquisition system based on the two-wire
technique (current loop 4 to 20 mA).

The transmitter is certified for applications in areas classified as:

- Ex II 1 G Ex ia IIC T5

- Ex II 1 G Ex ia IIC T6

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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 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 measured by the transmitter.
The latter signal is amplified and processed by the transmitter which supplies an
output signal 4 to 20 mA with two-wire technique (current loop) proportional to the
measurement under examination.

TYPICAL APPLICATIONS

- Pick up of measurements over definite measurement ranges, directly interfaceable

with a remote indicator able to supply the power to the transmitter (+24 Vdc rated

voltage).
Plants where the presence of a DCS or a PLC allows centralized control of the
measurements found and relative alarm thresholds (if present).

The transmitter is also provided with a BNC-F socket which supplies a signal with a
scale factor of 200mV/mil (8mV/µm) in accordance with API670 standard. This signal can
be used for diagnostics of the machinery under control (e.g. by means of a spectrum
analyzer).

COMPOSITION

The measuring chain is made up as follows:

- a field-mounted no contact sensor series API670, provided with a cable which can be

integral with the sensor or unpluggable from it through an intermediate connector

- a transmitter TR-NC/8, connected in turn to the sensor cable via a coaxial connector

TECHNICAL CHARACTERISTICS OF EACH MEASURING CHAIN

Basic composition : sensor, extension cable, transmitter

Type of measurement : differential

Dynamic range : frequency 5 to 5000 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 : ± 2%

Analog outputs : . 4 to 20mA–600 Ohm max. (current loop, 2-wire technique)
. BNC-F (scale factor 200mV/mil)

Power supply : +15 to +27Vdc; GND

Operating range : . temperature (sensor) = -35°C to +175°C
. temperature (transmitt.)= -20°C to +70°C (T5)
. temperature (transmitt.)= -20°C to +60°C (T6)
. humidity (sensor) = max 100%
. humidity (transmitter) = max 95% non condensing
. ambient (sensor) = IP67 EN 60529/10.91
. ambient (transmitter) = IP00 EN 60529/10.91

Connection : . miniaturized coaxial connector
(sensor / transmitter)
. screw terminal board model 476-CS/AL/4
(transmitter / user)

Weight of the transmitter : approx. 0.30 Kg

Weight of the sensor : approx. 0.10 Kg

Maintenance : None

Transmitter mounting : Connection for DIN rails: NS32-EN50035
NS35-EN50022

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Drawings : 56057 = Dimensions-mounting
38167 = Connections

Drawings to be
Required to CEMB : 53062/1÷6 = Types of sensor available
41670/1 = Types of extension available
54025/VB = Types of transmitter available for
Vibrations
54025/AX = Types of transmitter available for
Displacements
54025/PH = Types of transmitter available for
Phase

POSITIONING OF THE MEASURING CHAIN

Refer to dwg. 56057.

1) Make preparations on the machinery for mounting the sensor and any cable protection

devices (sheaths, ducts, etc.).

2) Separate (unless already disconnected) the extension cable and sensor parts from the
transmitter.

3) Mount the sensor with nominal air gap (Gap = 1.50 mm) on the device described in

point 1; GAP adjustment should be performed with the machinery in position K (ZERO

position with machine stationary) and is done by means of the thread of the sensor

and nuts (in standard kit) which act as nut/locknut (or else by means of a mounting

device provided with adjustment, e.g. supports Cemb series SR).
When mounting with two or more sensors, one alongside the other, it is necessary to
leave a minimum spacing of 25 mm in order to prevent mutual influence between the
signals.

4) Proceed to the electrical connection of the sensor to the transmitter and from the

latter to the measuring instrument as indicated in drawing 56057.

Min. supply voltage of the instrument should be 15 Vdc (+ 1 Vdc for every 50 ohm of

resistor inserted in the power supply loop), max. supply voltage should be 40 Vcc.

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