TECSYSTEM NT579 - Sensor Handling and Diagnostics; Temperature Sensor Connection and Transfer; Temperature Sensor Diagnostics

5
NT579-NT579 RS485
TECSYSTEM SHANGHAI
Disconnect the power supply to the instrument before making any
electrical connections
The contact fault is a fault signal, must not be connected to the trip-
ping circuit of the transformer
Is suggested protect the line of fans with a fuse appropriate for the
load to protect the unit
5) TEMPERATURE SENSOR CONNECTION
Each Pt100 temperature sensor has a white wire and two red wires (CEI 75.8
standards).
Figure 2 Page 11 shows the position inside the terminal box of the connection ca-
bles to the monitoring device.
6) MEASURING SIGNAL TRANSFER
All the measuring signal transfer cables for Pt100 must absolutely:
 be separated from the power ones
 be made with shielded cables and twisted conductors
 have at least 0,12 mm² section
 be twisted if there is no screen
 be firmly fixed inside the terminal boxes
 have tinned or silvered conductors
All the “NT” series monitoring units have the sensor signal linearization, with a
max. error of 1% of full scale value.
The maximum length of the extension cables with 0,12 mm² is 50 m.
The maximum length of the PT100 cable, using wires of 1mm² section, is 500m
7) TEMPERATURE SENSOR DIAGNOSTIC
In case of breaking of a temperature sensor mounted on the machine to protect,
FAULT relay immediately switches with the relevant indication of the defective
sensor on the corresponding channel.
 Fcc for short-circuited sensor or temperature below –15°C
 Foc for interrupted sensor or temperature over 230°C
 Fcd for rapid increasing of the reading (see note at page 18).
To remove the message and reset the Fault switching, it is necessary to verify
the Pt100 connections and, in case, replace the defective sensor.
If one channel is in FCD, the condition of ALARM and TRIP of that channel are
cleared
In case of FOC or FCC, the condition of FAN, ALARM and TRIP of the channel
are cleared.
TECSYSTEM has designed an own special cable to transfer the measuring
signals, according to CEI standards, with all the protection requirements pro-
vided for : model CT-ES