16
T154 WS
TEMPERATURE SENSOR DIAGNOSTICS
In case of failure or exceeded full scale value of one of the thermometric sensors installed on the machine to be protected,
the FAULT relay opens immediately with the relative warning of faulty sensor on the corresponding channel.
Fcc indicates sensor short-circuited or minimum full scale value of the control unit exceeded -8°C
Foc indicates sensor interrupted or maximum full scale value of the control unit exceeded 243°C.
To eliminate the message and to restore the Fault contact opening, check the connections of the Pt100 and replace the
faulty sensor if necessary. In case the minimum/maximum full scale value has been reached, make sure that the
environmental conditions correspond to what is indicated by the control unit.
Note: exceeding the minimum/maximum full scale can also be caused by possible disturbances on the sensor lines, in this
case the following are recommended:
Check correct installation of the sensors and especially of the extension cable (as indicated in the paragraph
MEASUREMENT SIGNALS TRANSFER).
Activation of the functions: VOTING (shown below) or FCD (on page 19) in relation to the system conditions.
CAL message display: the indication appears when the measurement circuit is damaged. The temperature values displayed
might be incorrect. Return the control unit to TECSYSTEM for repairs.
VOTING FUNCTION
The voting function derives from the redundancy concept that consists in duplicating the components of a system to increase
their
reliability
.
How does VOTING work?
Using the redundancy principle, we use the sensors installed on the three phases U-V-W to monitor the transformer's
operation, and at the same time to ascertain the sensors are working correctly, discriminating against any false alarms
(generated by installation errors).
By activating the
VOTING "YES"
function, the control unit compares the temperature values recorded on the monitored
CH1-CH2-CH3 channels and enables the switching of the(
TRIP)
disconnect contact only if the
TRIP
threshold has been
exceeded on at least two channels over the same period T.
By selecting
VOTING “NO”
the function will be disabled.
Note: if Voting "Yes” is programmed, the switching of the
ALARM
contact will signal exceeding of the alarm threshold on
each individual channel.
To enable the Voting function, read the programming section on pages 13-14.
Attention: To control the transformer correctly from a temperature point of view, enabling the VOTING function
is allowed where the load distributed between the phases of the transformer is adequately balanced. In addition,
any conditions of FAULT: FCC-FOC-FCD on two or more channels, with active voting, can determine the TRIP
contact inhibition.
PROGRAMMED DATA DIAGNOSTICS
In case of failure of the internal memory or corruption of programmed data, just after switching on,
Ech
appears with the
relevant Fault contact signal.
In this case, for safety reasons, the default parameters are loaded automatically (see programming table on pages 13-14).
Eliminate the
Ech
indication by pressing RESET and run programming to enter the desired values.
Finally switch the unit off and back on to check the memory works correctly, if it is damaged
Ech
will be displayed again
(send the control unit to TECSYSTEM srl for repairs).
