28
NT538
1. Cable 20 x AWG 20/19 Cu/Sn
2.
Section 0.55 mm²
3.
Flame retardant insulation PVC105
4.
CEI 20.35 IEC 332.1 regulations
5.
Maximum operating temperature: 90°C
6.
Conformation: 4 sets of three twisted and coloured conductors
7.
Shield in Cu/Sn
8.
Flame retardant PVC sheath
9.
External diameter 12mm
10.
Standard conformation in 100m coils
The NT series equipment boasts an innovative control function combined with the dynamic status of the Pt100 sensor.
Activating FCD, the control unit analyses the increase in temperature ∆T (*) recorded in a second (°C/sec).
Enabling the function, the user can select the value (∆T) from a minimum of 1°C/sec to a maximum of 30°C/ sec. If the
value sensed is higher than the value set by the user, the control unit inhibits the possible activation of the ALARM and
TRIP alarms and switches the FAULT relay (11-12), displaying the message "Fcd fault".
Example: if we set the function to 5°C, FAULT will switch for FCD only if the control unit senses an increase in ∆T of over
5°C in a second on the monitored system.
Setting "no" disables the FCD function.
When a channel is in FAULT for FCD, the relative Alarm and Trip warnings are inhibited; therefore only the over-quick
temperature increase is highlighted.
Press Reset to delete the FCD warnings on all channels and reset the FAULT relay.
Possible FCD applications
Identification of a possible induced interference on the Pt100 sensor line
If the installation instructions are not complied with (see page 16), any interference on the Pt100 sensor line can cause
false readings or anomalous alarms.
Setting the FCD function in a temperature range of between 1°C and 10°C (5°C recommended), the effects caused by
false readings can be suppressed and the alarm relay activation can be prevented, as shown above.
Corrective actions: check the installation of the sensor extension cable is in line with the instructions given in the
paragraph on the measurement signal transfer on page 16.
Identification of a sensor fault or faulty connection
In case of a faulty connection or sensor fault, a quick positive or negative variation in temperature might occur, leading to
the system tripping or the alarms of the monitored system to be triggered.
In this specific case we recommend the FCD function to be set in a temperature range of between 10°C and 20°C.
Corrective actions: check the terminals the sensor is connected to are tightened and replace the faulty sensor, if required.
Identification of the electrical motor rotor block
In case of temperature control of the electrical motors, the quick temperature increase might be due to a blocked rotor.
In this specific case we recommend the FCD function to be set in a temperature range of between 20°C and 30°C. This
setting is recommended in order to prevent the FCD function from activating during motor startup, or where the ΔT/sec.
increase varies quickly.
(*) The ΔT value shows the temperature range for each second.
NOTE: you should not enable the FCD function with active VOTING.
FCD FUNCTION
Pt100 EXTENSION CABLE TECHNICAL SPECIFICATIONS
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