ABB Power T&D Company Inc.
Power Automation and
Coral Springs, FL 33065
Instruction Leaflet
All possible contingencies which may arise during installation, operation or maintenance, and all details and
variations of this equipment do not purport to be covered by these instructions. If further information is
desired by purchaser regarding this particular installation, operation or maintenance of this equipment, the
local ABB Power T&D Company Inc. representative should be contacted.
Printed in U.S.A
.
Protection Division
!
CAUTION
Before putting protective relays into service,
remove all blocking which may have been
inserted for the purpose of securing the parts
during shipment, make sure that all moving
parts operate freely, inspect the contacts to
see that they are clean and close properly, and
operate the relay to check the settings and
electrical connections.
1. APPLICATION
The KLF-1 relay is a single-phase relay connected to
the ac side of a synchronous machine and contains
three units connected so that the operation of two
units sounds an alarm warning the operator of a low
excitation condition, and the additional operation of
the third unit sets up the trip circuit. The relay can be
applied without modification to all types of synchro-
nous machines, such as turbo-generator, water
wheel generator or synchronous condensers.
This relay is designed for circuits using 4 wire
wye-connected voltage transformers. Separate
phase-to-ground voltages applied to the directional,
impedance and under-voltage elements, thus mini-
mizing the chance of false operation due to inadvert-
ent loss-of-potential (such as due to a blown potential
fuse). On circuits with 3-phase 3-wire connected volt-
age transformers, the type KLF relay is used.
2. CONSTRUCTION
The relay consists of two air-gap transformers (com-
pensators), two tapped autotransformers, one reac-
tor, one cylinder-type distance unit, directional unit
with adjustable resistor, an undervoltage unit with
adjustable resistor, telephone relay, and an ICS indi-
cating contactor switch.
2.1.
COMPENSATOR
The compensators which are designated T
A
and T
C
are two-winding air-gap transformers (figure 2). The
primary or current winding of the long-reach-compen-
sator T
A
has seven taps which terminate at the block.
They are marked 2.4, 3.16, 4.35, 5.93, 83, 11.5, 15.8.
The primary winding of the short-reach compensator
T
C
also has seven taps which terminate at this tap
block. They are marked 0.0, 0.91, 1.27, 1.82, 2.55,
3.64, 5.1. A voltage is induced i the secondary which
is proportional to the primary tap and current magni-
tude. This proportionality is established by the cross
sectional area of the laminated steel core, the length
of an air-gap which is located in the center of the coil,
and the tightness of the laminations. All of these fac-
tors which influence the secondary voltage propor-
tionality have been precisely set at the factory. The
clamps which hold the laminations should not be dis-
turbed by either tightening or loosening the clamp
screws.
The secondary winding is connected in series with
the relay terminal voltage. This a voltage which is
proportional to the line current is added vectorially to
the relay terminal voltage.
41-748.1F
Effective:
December 1996
Supersedes I.L. 41-748.1E dated February 1984
( | ) Denotes Change Since Previous Issue
Type KLF-1
Loss-of-Field Relay
(50/60 Hertz)
