ABB REQ650 - Example 1

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 22.
Protected Object
Line, transformer, etc
ForwardReverse
Definition of direction
for directional functions
Measured quantity is
positive when flowing
towards the object
e.g. P, Q, I
ReverseForward
Definition of direction
for directional functions
e.g. P, Q, I
Measured quantity is
positive when flowing
towards the object
Set parameter
CTStarPoint
Correct Setting is
"ToObject"
Set parameter
CTStarPoint
Correct Setting is
"FromObject"
en05000456.vsd
IEC05000456 V1 EN
Figure 22: Internal convention of the directionality in the IED
With correct setting of the primary CT direction, CTStarPoint set to FromObject or
ToObject, a positive quantity always flows towards the protected object and a
direction defined as Forward is always looking towards the protected object. The
following examples show the principle.
4.2.3.1 Example 1
Two IEDs used for protection of two objects.
1MRK 505 291-UEN A Section 4
Analog inputs
63
Application manual