ABB RELION RET670, Applications Manual

Page: 76 / 1016

4.2.1.1 Example
SEMOD55055-11 v5
Usually the A phase-to-ground voltage connected to the first VT channel number of the
transformer input module (TRM) is selected as the phase reference. The first VT
channel number depends on the type of transformer input module.
For a TRM with 6 current and 6 voltage inputs the first VT channel is 7. The setting
PhaseAngleRef =7 shall be used if the phase reference voltage is connected to that
channel.
4.2.2 Setting of current channels
SEMOD55055-16 v6
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 Wye (star) connected and can be
connected with the grounding 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
7
A positive value of current, power, and so on (forward) means that the quantity flows
towards the object. A negative value of current, power, and so on (reverse) means that
the quantity flows away from the object. See Figure
7 .
Protected Object
Line, transformer, etc
Forward Reverse
Definition of direction
for directional functions
Measured quantity is
positive when flowing
towards the object
e.g. P, Q, I
Reverse Forward
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"
en05000456-2.vsd
ANSI05000456 V2 EN-US
Figure 7: Internal convention of the directionality in the IED
With correct setting of the primary CT direction, CT_WyePoint set to FromObject or
ToObject , a positive quantities always flowing towards the protected object and a
direction defined as Forward always is looking towards the protected object. The
following examples show the principle.
Section 4
1MRK 504 163-UUS A
Analog inputs
70 Transformer protection RET670 2.2 ANSI
Application manual