ABB RET670 Applications Manual page 45

1MRK504116-UUS C
Application manual
Regardless which one of the above two options is selected busbar differential
protection will behave correctly.
The main CT ratios must also be set. This is done by setting the two parameters CTsec
and CTprim for each current channel. For a 1000/5 A CT the following setting shall be
used:
• CTprim = 1000 (value in A)
• CTsec =5 (value in A).
Examples on how to connect, configure and set CT inputs for most
commonly used CT connections
Figure 7 defines the marking of current transformer terminals commonly used around
the world:
In the SMAI function block, you have to set if the SMAI block is
measuring current or voltage. This is done with the parameter:
AnalogInputType: Current/voltage. The ConnectionType: phase -phase/
phase-earth and GlobalBaseSel.
I
Sec
x
a)
IEC06000641 V1 EN
Figure 7: Commonly used markings of CT terminals
Where:
a) is symbol and terminal marking used in this document. Terminals marked with a dot indicates
the primary and secondary winding terminals with the same (that is, positive) polarity
b) and c) are equivalent symbols and terminal marking used by IEC (ANSI) standard for CTs. Note that
for these two cases the CT polarity marking is correct!
P1
(H1)
S1 (X1)
S2 (X2)
x
P2
(H2)
b)
Section 3
IED application
P2
(H2)
S2 (X2)
S1 (X1)
P1
(H1)
c)
en06000641.vsd
39