Setting Of Current Channels; Example 1 - ABB RELION 650 Series Applications Manual

Section 4
Analog inputs
4.2.2

Setting of current channels

The direction of a current to the IED is depending on the connection of the CT. Unless
indicated otherwise, the main CTs are supposed to be star connected and can be connected
with the earthing point to the object or from the object. This information must be set in the
IED. The convention of the directionality is defined as follows: A positive value of current,
power, and so on means that the quantity has the direction into the object and a negative
value means direction out from the object. For directional functions the direction into the
object is defined as Forward and the direction out from the object is defined as Reverse. See
figure 3
A positive value of current, power, and so on (forward) means that the quantity has a direction
towards the object. - A negative value of current, power, and so on (reverse) means a direction
away from the object. See figure 3.
Definition of direction
for directional functions
Reverse
Set parameter
CTStarPoint
Correct Setting is
"ToObject"
IEC05000456 V1 EN-US
Figure 3:
With correct setting of the primary CT direction,
positive quantities always flowing towards the object and a direction defined as Forward
always is looking towards the object. The following examples show the principle.
4.2.2.1

Example 1

Two IEDs used for protection of two objects.
34
Forward
Protected Object
Line, transformer, etc
e.g. P, Q, I
Measured quantity is
positive when flowing
towards the object
Internal convention of the directionality in the IED
Definition of direction
for directional functions
Forward Reverse
e.g. P, Q, I
Measured quantity is
positive when flowing
towards the object
Set parameter
CTStarPoint
Correct Setting is
"FromObject"
en05000456.vsd
CTStarPoint set to FromObject or ToObject , a
1MRK 505 363-UEN A
SEMOD55055-16 v5
SEMOD55055-23 v5
Application manual