ABB Remote I/O RIO600, Руководство по установке и пусконаладке, Страница: 115 / 312

Maximum torque line
Min forward angle
Min reverse angle
Min operate
current
Max forward angle
Max reverse angle
Backward
operating zone
Zero torque line
N
o
n
-o
p
e
ra
ti
n
g
z
o
n
e
Forward
operating zone
Characteristic angle
= -90°
Io
(Operating quantity)
-Uo (Polarizing quantity)
GUID-E829A47B-A6C1-46AD-99B8-5F3E9D234B70 V1 EN
Figure 61: Definition of the relay characteristic angle, RCA = -90° in an isolated
network
Directional earth-fault detection in an isolated neutral network
In isolated networks, there is no intentional connection between the system neutral
point and earth. The only connection is through the phase-to-earth capacitances (C0)
of phases and leakage resistances (R0). This means that the residual current is mainly
capacitive and has a phase shift of -90° compared to the polarizing voltage.
Consequently, the relay characteristic angle (RCA) should be set to -90° and the
operation criteria to "IoSin" or "Phase angle". The width of the operating sector in the
phase angle criteria can be selected with the settings
Min forward angle , Max forward
angle , Min reverse angle or Max reverse angle . Figure 62 illustrates a simplified
equivalent circuit for an unearthed network with an earth-fault in phase C.
For definitions of different directional earth-fault characteristics, see
Directional earth-fault principles.
1MRS757488 H
Section 6
Commissioning
RIO600 107
Installation and Commissioning Manual