ABB Modures LZ92-1 User Manual

1. APPLICATION
The solid-state distance relays LZ91, LZ92 and LZ92-l have been designed for
high-speed discriminative protection applications, primarily in medium-voltage
systems. They are equally suitable for cable and overhead line circuits and the
power systems may be ungrounded, impedance or solidly grounded.
When protecting extremely short lines, the distance relays are already equipped
with the logic to operate in a directional comparison scheme (permissive over-
reaching transfer tripping) with pilot wires. The corresponding pilot wire
ancillaries have the type designations ER91 and NR91.
The relays are also prepared for operating in conjunction with an auto-reclosure
relay (e.g. type WT91 for three-phase reclosure).
All the relays are of the switched type, having starting units (fault detectors)
which apply the correct fault quantities to a single direction and distance
determining measuring system. The starting units of the LZ91 operate on overcur-
rent, so that the relay is simpler and more economical, but can only be applied
in systems in which the lowest fault current is clearly greater than the maximum
load current. Both the LZ92 and the LZ92-l are equipped with true underimpedance
uni ts (not just voltage-controlled overcurrent) and are thus capable of detec-
ting weak faults at times of low generation with fault currents below the
maximum load currents at peak periods.
A full description of their operation is contained in publication CH-ES 23-92.lOE
"Solid-state distance relays types LZ91, LZ92 and LZ92-l" and their technical
data is given in data Sheet CH-ES 63-92.10 E.
2. MECHANICAL DESIGN
The various plug-in units which make up the relays are accommodated in standard
19" electronic equipment racks, and these in turn are either grouped together
with other relays in cubicles, or fitted into casings for surface or semiflush
switchpanel mounting. The corresponding dimensioned drawings are in the appendi-
ces to these instructions.
The plug-in units have a standard height of 3,5 U (U = 44.45 mm) and varying
widths given as a number of divisions T (T = 17 mm). One 19" rack has space for
plug-in units adding up to a maximum of 24 T.
The standard versions of the distance relays LZ91, LZ92 and LZ92-l only require
20 T, which is less than one full rack.
The distance relays comprise the following plug-in units:
- input transformer unit type EW91, width 6 T, also containing signal conditio-
ning circuits, measuring sockets and auxiliary tripping relay.
- main processing unit: KI91 for LZ91, KZ91 for LZ92 or KZ91-l for LZ92-l. The
terminals of the main processing units are compatible and they have the same
width.
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ABB Modures LZ92-1 Specifications

General

Brand	ABB
Model	Modures LZ92-1
Category	Relays
Language	English