ABB REG316 4 Series Operating Instructions Manual page 139

REG 316*4 1MRB520049-Uen / Rev. F
Characteristic angle
Determining the phase-angle of the current provides an addi-
tional criterion for preserving discrimination compared with non-
directional overcurrent protection. The directional sensitivity is
± 180° in relation to the reference voltage. This is illustrated in the
following diagrams. The angles given apply for connection ac-
cording to the connections in
I
R
j
w
U
R
U U
TR RS
U U
T S
U
ST
a)
j ' = phase-angle between current and voltage
(positive angle)
a = Characteristic angle
L = Border line between operating and restraint areas
a) Definition of current
and voltage
Fig. 3.5.8.2 Vector diagram for a fault in the forwards direction on
R phase
The function determines the power direction by measuring the
phase-angle of the current in relation to the opposite phase-to-
phase voltage. Which current is compared with which voltage
can be seen from the following table.
Current input Phase-to-neutral voltage
I U , U
R S
I U , U
S T
I U , U
T R
Section 12.
L
Restraint:
cos ( - ) = neg. j a
'
b)
b) Operating characteristic
T
R
S
ABB Switzerland Ltd
I
R
a = 45°
j'
U
ST
Operation:
j a
cos ( - ) = pos. '
L
HEST 005 001 C
Calculated voltage
U = U - U
ST S T
U = U - U
TR T R
U = U - U
RS R S
3-101