ABB Modures LZ92-1 User Manual

- Either an OR or an AND interlocking logic can be used (see parts of the
ordering code headed EKl or EK2 in the tables of features Table 9 .17,
Table 9.18 and also Fig. 9.25).
The LED signal labelled "E" will only light up when both the earth fault
detector and at least one underimpedance phase element have picked up.
3.2.2.2 Reach of the underimpedance elements
8
standard characteristic
The standard under impedance starting characteristic is a circle with its
centre at the origin of the impedance plane. The relationships for an earth
fault R-0 are:
-
ULiR
-
Ul:R
-
·goo
--
UR
-
2
X eJ
IR
A
-
j90
-
u +
2
XBe
IR
R
XA = XB
replica reactance in forward direction
replica reactance in backward direction
Criterion for pick-up:
u:R j_
The reach for radial lines and the different kinds of faults is:
- phase-to-phase fault: same as setting
- three-phase fault
- earth fault
2
: x setting
13
2
1 + k
oL
x setting
(k = K of the line)
oL o
ABB has a computer programme for checking the relay settings for all kinds
of faults and fault locations where complex system conditions prevail.
The starters must reliably pick up for a fault at the end of the next
section of line (back-up zone). Where the back-up zone is not being taken
specifically into account, the setting must be at least 1. 3 times the
impedance of the protected line. The influence of arc resistance must also
be considered in the case of short lines.

ABB Modures LZ92-1 Specifications

General

Brand	ABB
Model	Modures LZ92-1
Category	Relays
Language	English