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1.2 INTRODUCTION
1 PRODUCT DESCRIPTION
1.2 INTRODUCTION
1.2.1 DESCRIPTION
1
The Line Protection System (LPS) is a microprocessor-based digital relay system that uses waveform sam-
pling with appropriate algorithms to provide either three phase or single phase tripping schemes for transmis-
sion line protection, fault location, and related features. The LPS-D models covered by this instruction book are
intended for either three phase or single phase tripping applications. The LPS-D relay samples the current and
voltage inputs from the power system 64 times per cycle. The protection algorithms process this sampled data
in sets of four, sixteen times per cycle. The LPS-D uses advanced Fourier calculation techniques and adaptive
measuring functions to achieve high-speed tripping for severe faults.
The LPS-D is packaged in a compact 3 Rack Unit high (one RU = 1.75 Inch) 19-inch rack mount case which is
available for either horizontal or vertical mounting. The case outline and mounting dimensions for the LPS-D
are shown in Figure 3–1: DIMENSIONS on page 3–1.
All LPS-D models include a full keypad and a liquid crystal display (LCD) for local access to relay data and set-
tings. In addition, up to three communication ports are provided for both local and remote access via a PC.
Each port may be independently set for an ASCII protocol or GEmodem protocol.
1.2.2 APPLICATION
The LPS-D models covered by this instruction book are designed to be used on transmission lines of any volt-
age level where either single or three phase tripping is required. Detailed application considerations are
described in this chapter and in Chapter 2: CALCULATION OF SETTINGS.
The LPS-D can provide high speed detection and clearing of power system faults, and includes logic for step
distance and five standard pilot tripping schemes. The scheme logic diagrams are shown and discussed in
Section 1.8: PROTECTION SCHEME DESCRIPTIONS on page 1–26. The external connections for the LPS-D
are shown in the elementary diagram of Figure 1–23: ELEMENTARY DIAGRAM on page 1–48.
The LPS-D is available with either a contact interface to the pilot channel equipment or an electronic (5 V, 20
mA) interface, so that the relay may be applied with a wide variety of channel equipment. Typical channels
include: AM and FSK via power line carrier (PLC), FSK via microwave, and multiplexed fiber optic cable.
1.2.3 PROTECTION FUNCTIONS
The measurement functions included are listed in Table 1–2: LPS-D MEASUREMENT FUNCTIONS below.
The Zone 1 distance functions provide secure tripping for all fault types over most of the protected line. The
Zone 1 ground distance functions can be selected to be either ground variable-Mho distance functions or
ground-reactance distance functions. A unique adaptive reach for the supervising Mho characteristic is used
when ground-reactance functions are selected.
Overreaching Zone 2 phase and ground distance functions are used for pilot tripping schemes. Ground-direc-
tional overcurrent functions can be selected to replace or supplement the overreaching zone (Zone 2) ground-
distance functions in any of the pilot schemes. For revision level B models of the LPS-D, the Zone 2 ground
quadrilateral characteristic may also be selected. The Zone 2 phase and ground distance functions are pro-
vided with independent timers for time delayed backup protection.
Overreaching Zone 3 phase and ground distance functions are provided with independent timers for time
delayed backup protection. The LPS-D with revision B firmware also has the option for quadrilateral ground
distance functions
1-
LPS-D Line Protection System
GE Power Management
4
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