CEMB USA TR-NC8 ATEX - Manual (Page 2)

2
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 temp-
erature 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