S M ART T EMP ER ATUR E MONITORI NG R EL AYS
STATUS
Approved
SECURITY LEVEL
Public
DOCUMENT ID.
2CDC112285M0201
REV.
B
LANG.
en
PAGE
24/42
© Copyright 2020 ABB. All rights reserved.
Threshold
Entering the threshold menu allows setting of the signal source, over- or under-
temperature monitoring and the temperature value. Signal source refers to the
sensor circuit from which the measured temperature values is taken as reference
to the configured threshold. The CM-TCN provides three independent sensor cir-
cuits: 1T1/1T2/1T3, 2T1/2T2/2T3 and 3T1/3T2/3T3
Signals 1 – Threshold:
The currently selected parameter is underlined, signaling it can be changed by
rotating. After adjusting the new value, another push action confirms the new
selection or exits the configuration.
Threshold – Channel selection:
Clicking on
leads back to the next higher menu stage. Alternatively, the but-
ton can be pressed for 2 seconds.
Hysteresis
In this sub-menu the hysteresis related to the configured threshold can be set.
The term hysteresis refers to the release of an energized relay after its threshold
value has been reached again.
Example: The relay picks up if the temperature rises above 100 °C, i.e. over-
temperature detected, output relay is energized (open-circuit principle), but it
does not de-energize immediately if the temperature decreases to the threshold
value of 100 °C again but only after the threshold minus hysteresis value has
been reached e.g. 95 °C.
The hysteresis is given as an absolute value added or subtracted to the thresh-
old value depending if the configuration is under- or overtemperature monitor-
ing. The release hysteresis prevents the relay from continuously switching on
and off in case of temperature variations around the threshold value.