Ct And Vt Inputs; Overview Of Functions; Structure Of The Function; Application And Setting Notes - Siemens 7SR51 Device Manual

Device Functionality

3.3 CT and VT Inputs

3.3 CT and VT Inputs

Overview of Functions

3.3.1
All device CT and VT inputs are configured in the Configuration > CT/VT menu.
The devices have a minimum of four current inputs. Where the device functionality requires further current
inputs these are available in groups of four i.e. as an additional 4 CT or 8 CT inputs.
Where the device has voltage inputs then four VT inputs are provided.
Inputs from the primary system current and voltage transformers are converted to levels used by the protec-
tion and automation functions of the relay. The CT and VT input configuration settings ensure that the primary
instrument and meter values are correctly displayed and logged.
3.3.2

Structure of the Function

Analogue inputs for the CTs and VTs are supplied in groups of four CTs and four VTs inputs.
The first 3 numbered CT and VT inputs are grouped together and have the same group of configuration
parameters e.g. CT1/2/3 and VT1/2/3. The fourth input has separate configuration parameters e.g. CT4 and
VT4.
Typical connections are shown in
[dw_7SR5_7SR51CTVTInputConnections, 1, en_US]
Figure 3-5

Application and Setting Notes

3.3.3
Parameter: CT1/2/3 Nominal
•
Default setting: 2000
This setting is used to select the device CT input measuring range for the 3 line CT inputs. The setting
value is used by the device instrumentation e.g. to display ⋅ I
Parameter: CT1/2/3 Ratio Prim
•
Default setting: 1A
The setting value is used (in conjunction with CT1/2/3 Ratio Sec setting) by the device instrumenta-
tion e.g. to display primary current values.
60
Figure 3-5.
Typical CT and VT Input Connections
values (nominal values).
rated
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019