Introduction; Description; Application; Protection Functions - GE LPS-O Instruction Manual

1.2 INTRODUCTION

1 PRODUCT DESCRIPTION
1.2 INTRODUCTION

1.2.1 DESCRIPTION

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The Line Protection System (LPS) is a microprocessor-based digital relay system that uses waveform sam-
pling with appropriate algorithms to provide three phase tripping schemes for transmission line protection and
system backup. The LPS-O models covered by this instruction book are intended for three-phase tripping
applications. The LPS-O relay samples the current and voltage inputs from the power system 64 times per
cycle. The protection algorithms process the sampled data in sets of four, sixteen times per cycle. The LPS-O
relay also uses advanced Fourier calculation techniques and adaptive measuring functions to achieve high-
speed tripping for severe faults.
The LPS-O 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-O
are shown in Figure 3–1: FRONT AND REAR VIEWS OF THE LPS-O on page 3–1.
All models of the LPS-O relay include a full keypad and a liquid crystal display (LCD) for local access to relay
data and settings. 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-O is a modified version of the ALPS relay system. It is primarily intended for system backup (Phase
impedance) and out-of-step trip protection at generator terminals. The overcurrent and impedance functions of
the LPS-O can be used to complement Generator Protection relay systems like the DGP and SR489.
Also, the LPS-O may be used for line protection. It can provide three zones of phase distance and ground
overcurrent protection for either solidly grounded or resistance grounded systems where ground distance func-
tions may not provide reliable protection.
The external connections for the LPS-O are shown in the elementary diagram of Figure 1–11: ELEMENTARY
DIAGRAM on page 1–25. Note that the relay uses 3-wire voltage inputs and is suitable for either delta or wye
connected VTs. All Contact Converter inputs and Contact Outputs of the LPS-O are user configurable. The ele-
mentary diagram also shows default assignments of the Inputs/Outputs which can be changed by the user.
The measurement functions included are listed in Table 1–2: LPS-O MEASUREMENT FUNCTIONS.

1.2.3 PROTECTION FUNCTIONS

The measurement functions included are listed in Table 1–2: LPS-O MEASUREMENT FUNCTIONS below.
The Zone 1 distance functions provide secure tripping for all fault types over most of the protected line. The
Zone 1 phase distance functions are variable-mho distance functions.
Overreaching Zone 2 phase distance functions can be used for the Step Distance protection scheme. Ground-
directional overcurrent functions can be selected to replace or supplement the Zone 2 phase-distance func-
tions in the Step Distance scheme. The Zone 2 phase distance functions are provided with independent timers
for time delayed backup protection.
Zone 3 phase distance functions are provided with independent timers for time delayed backup protection.
The Zone 4 variable-mho phase distance functions can be used when a reversed function is required. The
Zone 4 phase distance functions are provided with independent timers for time delayed backup protection.
1- LPS-O Line Protection System GE Power Management
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