INSTA L L A Tl ON
•
Westinghouse
1. L. 41-l33.3E
OPERATION
•
MAI N TENANCE
INSTRUCTIONS
TYPE IRV DIRECTIONAL OVERCURRENT RELAY
FOR PHASE PROTECTION
C A U T I O N
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.
A P P L I CA T I ON
These relays are phase directional overcurrent
relays which are used for the protection of trans
mission lines and feeder circuits. Both the time
overcurrent and instantaneous overcurrent units are
directionally controlled.
CONST RUCTION AN D O P E RATION
The Type IRV relay consists of a directional
unit
(D),
an auxiliary switch (Cs-1), a time-overcurrent
unit (CO), an instantaneous overcurrent unit (I), an
instantaneous overcurrent unit transformer, and two
indicating contactor switches (ICS/I) and (ICS/T).
The principle component parts of the relays and their
location are shown in Fig. 1 and 2.
T i me- O v ercurrent U n i t ( C O )
The electromagnets for the types C0-5, C0-6,
C0-7, CQ-8 and C0-9 units have a main tapped coil
located on the center leg of an
"E"
type laminated
structure that produces a flux which divides and re
turns 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
causes a contact closing torque.
The electromagnet for the type C0-2 and C0-11 units
have 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 connect
ed to the main coil secondary in a manner so that the
combination of all the fluxes produced by the electro
magnet result in out-of-phase fluxes in the air gap.
The out-of-phase air gap fluxes produced cause a
contact closing torque.
SUPERSEDES I.L. 41-133.3D
'Denotes change from superseded 1ssue.
I n d i c at i ng Co ntactor S w i t c h U n i t s ( IC S/1 and I C S/T)
The d-e 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 contacts 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,
provides restraint for the armature and thus controls
the pick-up value of the switch.
D i recti onal U n i t { D )
The directional unit is a product induction cylin
der 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 electromagnet, a moving element assembly, and
a
molded bridge.
The frame serves as the mounting structure for
the magnetic core. The magnetic core which houses
the lower pin bearing is secured to the frame by a
spring and snap ring. This is an adjustable core
which has a .025 inch flat on one side and is held in
its adjusted position by the clamping action of two
compressed springs. The bearing can be replaced, if
necessary, without having to remove the magnetic
core from the frame.
The electromagnet has two series-connected
polarizing coils mounted diametrically opposite one
another, two series-connected operating coils mounted
diametrically opposite one another; two magnetic ad
justing plugs; upper and lower adjusting plug clips,
and two locating pins. The locating pins are used to
accurately position the lower pin bearing, which is
mounted on the frame, with respect to the upper pin
bearing, which is threaded into the bridge. The elec-
EFFECTIVE MAY 1971
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