TECSYSTEM NT579, Инструкция по эксплуатации

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20
NT579-NT579 RS485
TECSYSTEM SHANGHAI
21) NOTES ABOUT FCD FUNCTION
NT device series have an innovative control function combined with the
Pt100 sensor dynamic state.
If a temperature sensor should accidentally break down, the defect turns out
with a fast increase of its resistance and therefore of the temperature
registered by the monitoring unit.
It is obvious that this increase is not consequential to the increase of power
of the machine to be protected, whether it is a motor or a dry or
encapsulated transformer.
Therefore it is advisable to discriminate the state of the sensor and report a
Fault notification rather than an Alarm or, worse, a Trip signal.
In case of temperature control for electrical motors, the fast increase of the
temperature could be the consequence of the working with jammed rotor
and not of defective sensor; in this case the Fault relay, once energised,
makes evident this anomalous condition for the motor working.
By activating the FCD function it is possible to have on 54-55 contacts a
Fault signal when the temperature registered by a Pt100 increases with a
speed higher than
“n” °C/sec (loadable from 1 to 30).
Depending on the loaded value, you can have a different sensitivity, which
can be useful for various applications:
-
from 1 to 10 : high sensitivity, for instance useful to immediately report a
jammed rotor in a motor.
-from
10 to 20 : medium sensitivity, useful to have indications for possible
noises which affect the sensor reading, connection problems or defective
sensors.
-from
20 to 30 : low sensitivity, useful for applications where an higher
sensitivity could give rise to faults for undesired FCD.
- loading
“no” , FCD function is disabled.
When a channel is in Fault condition for FCD, relevant Alarm and trip
signalling are inhibited in order to just report the anomaly for too fast
increase of the temperature.
Press Reset to cancel the FCD signalling of all the channels and restore the
fault relay.