Analog Input Data; Configuration For Analog Ct Inputs - ABB REL670 Installation And Commissioning Manual

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Analog input data

Analog input data
In order to get correct measurement results as well as correct protection functionality, the analog
input channels must be configured. Because all protection algorithms in the IED utilize the pri-
mary system quantities it is extremely important to make sure that connected current transformer
settings are done properly. These data are calculated by the system engineer and normally set by
the commissioner from the local HMI or from the SMS.

Configuration for analog CT inputs

The analog inputs on the Transformer Module (TRM) are dimensioned for either 1A or 5A. Each
TRM has a unique combination of current and voltage inputs. Make sure the input current rating
is correct and that it matches the order documentation.
The primary CT data are entered from the HMI menu branch:
Settings\General Settings\Analog modules\AnalogInputsnn
The following parameter shall be set for every current transformer connected to the IED:
Table 14: CT configuration
Parameter description
Rated CT primary current in A
This parameter defines the primary rated current of the CT. For two set of CTs with ratio 1000/1
and 1000/5 this parameter is set to the same value of 1000 for both CT inputs. Negative values
(i.e. -1000) can be used in order to reverse the direction of the CT current by software for the
differential function. This might be necessary if two sets of CTs have different star point loca-
tions in relation to the protected busbar. It is recommended that this parameter is set to zero, for
all unused CT inputs.
For main CTs with 2A rated secondary current, it is recommended to connect the secondary wir-
ing to the 1A input and to set the rated primary current to one half times its true value. For ex-
ample, a CT with a primary secondary current ratio of 1000/2A can be treated as a 500/1A CT.
Configuring the IED and changing
Parameter name Range
CT Prim Input from -10000 to +10000
Chapter 10
settings
Default
0