ABB Automation Inc.
Substation Automation and Protection Division
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
.
Directional Overcurrent
41-133S
Ground Relays
Types IRP, IRC and IRD
Supersedes I.L. 41-133R, Dated August 1998
( )
Denotes Changed Since Previous Issue
Effective: October 1999
Before putting 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.
1.0 APPLICATION
These relays are ground directional overcurrent
relays which are used for the protection of transmis-
sion lines and feeder circuits. Both the time overcur-
rent and instantaneous overcurrent units are
directionally controlled.
The type IRP relay is potential polarized. The type
IRC relay is current polarized. The type IRD relay is a
dual polarized relay which can be polarized from a
potential source, from a local ground source or from
both simultaneously.
2.0 CONSTRUCTION AND OPERATION
The various types of relays consist of a directional
unit or units (D), an auxiliary switch (CS-1 or a tele-
phone relay TR-1), a time-overcurrent unit (CO), an
instantaneous overcurrent unit (I), an instantaneous
overcurrent unit transformer, and two indicating con-
tactor switches (ICS/I) and (ICS/T). The principle
component parts of the relays and their locations are
shown in Figures 1 through 6, starting on page 19.
2.1 TIME-OVERCURRENT UNIT (CO)
The electromagnets for the types IR-5, IR-6, IR-7,
IR-8 and IR-9 relays have a main tapped coil located
on the center leg of an “E” type laminated structure
that produces a flux which divides and returns
through the outer legs. A shading coil causes the flux
through the left leg to lag the main pole flux. The
out-of-phase fluxes thus produced in the air gap
cause a contact closing torque.
The electromagnet for the type IR-2 and IR-11 relays
has a main coil consisting of a tapped primary wind-
ing and a secondary winding. Two identical coils on
the outer legs of the lamination structure are con-
nected to the main coil secondary in a manner so that
the combination of all the fluxes produced by the
electromagnet result in out-of-phase fluxes in the air
gap. The out-of-phase air gap fluxes produced cause
a contact closing torque.
The dc indicating contactor switch is a small clapper
type device. A magnetic armature, to which
leaf-spring mounted contacts are attached, is
attracted to the magnetic core upon energization of
the switch. When the switch closes the moving con-
tacts bridge two stationary contacts, completing the
trip circuit. Also during this operation two fingers on
the armature deflect a spring located on the front of
the switch, which allows the operation indicator target
to drop.
The front spring, in addition to holding the target, pro-
vides restraint for the armature and thus controls the
pickup value of the switch.
2.2 DIRECTIONAL UNIT (D)
The directional unit is a product induction cylinder
type unit operating on the interaction between the
polarizing circuit flux and the operating circuit flux.
Mechanically, the directional unit is composed of four
basic components: A die-cast aluminum frame; an
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CAUTION
