ABB RES670 Technical Manual page 76

Section 3
Analog inputs
70
For directional functions the directional conventions are defined as follows (see Figure
2)
• Forward means the direction is into the object.
• Reverse means the direction is out from the object.
Definition of direction
for directional functions
Reverse Forward
e.g. P, Q, I
Measured quantity is
positive when flowing
towards the object
Set parameter
CTStarPoint
Correct Setting is
"ToObject"
ANSI05000456 V2 EN-US
Figure 2: Internal convention of the directionality in the IED
If the settings of the primary CT is correct, that is CTStarPoint set as FromObject or
ToObject according to the plant condition, then a positive quantity always flows
towards the protected object, and a Forward direction always looks towards the
protected object.
The settings of the IED is performed in primary values. The ratios of the main CTs and
VTs are, therefore, basic data for the IED. The user has to set the rated secondary and
primary currents and voltages of the CTs and VTs to provide the IED with their rated
ratios.
The CT and VT ratio and the name on respective channel is done under Main menu/
Hardware/Analog modules in the Parameter Settings tool or on the HMI.
Protected Object
Line, transformer, etc
Measured quantity is
positive when flowing
Phasor measurement unit RES670 2.2 ANSI
1MRK 511 408-UUS A
Definition of direction
for directional functions
Forward Reverse
e.g. P, Q, I
towards the object
Set parameter
CTStarPoint
Correct Setting is
"FromObject"
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