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41-133S
6.0 INSTALLATION
The relays should be mounted on switchboard pan-
els or their equivalent in a location free from dirt,
moisture, excessive vibration and heat. Mount the
relay vertically by means of the rear mounting stud or
studs for the type FT projection case or by means of
the four mounting holes on the flange for the
semi-flush type FT case. Either the stud or the
mounting screws may be utilized for grounding the
relay. External toothed washers are provided for use
in the locations shown on the outline and drilling plan
to facilitate making a good electrical connection
between the relay case, its mounting screws or
studs, and the relay panel. Ground Wires should be
affixed to the mounting screws or studs as required
for poorly grounded or insulating panels. Other elec-
trical connections may be made directly to the termi-
nals by means of screws for steel panel mounting or
to the terminal stud furnished with the relay for thick
panel mounting. The terminal stud may be easily
removed or inserted by locking two nuts on the stud
and then turning the proper nut with a wrench.
For detail information on the FT case refer to I.L.
41-076.
The external ac connections of the directional over-
current relays are shown in Figures 13, 14, and 15
(on page 28, page 29, and page 30). If no voltage
polarizing source is to be connected to the IRD relay,
short-circuit the voltage polarizing circuit at the termi-
nals of the relay.
6.1 REVERSED CONTACTS
In installations where the relay could be exposed to
unusual shock or jarring, the possibility of inadvertent
contact closure can be reduced by reversing the ori-
entation of the directional unit contacts. Contact
arrangement and wiring would be reversed on the
directional unit. Its contact would then mechanically
close in a direction opposite to that of the instanta-
neous unit contact. Electrical characteristics and
external connections to the relay would not be
affected. Field modifications can be made per the
following procedures.
1. Reverse the leads on the stationary contacts
of the directional unit. For the IRD, reverse
the leads on both directional units.
6
Directional Overcurrent Ground Relays
2. Reverse the leads to switch jaw terminals 6
and 7. For the IRD, also reverse leads to
switch jaw terminals 4 and 5.
3. Move the spring adjuster on each directional
unit such that the left hand contacts are
normally closed.
4. Remove, then reverse the right hand and left
hand stationary contacts on each directional
unit. Adjust the left hand contact until it just
makes with the moving contact, then
advance it an additional 1/2 turn in. Now
adjust the right hand stationary contact until
it just makes with the moving contact, then
screw it out 3/4 turn for a contact gap of
.020" to .024".
5. Calibrate each directional unit per proce-
dures beginning at section 7.4.1.c.
For relays whose contacts have been
reversed, it is recommended that a sub letter
"R" be added to the nameplate at the end of
the style number to designate that the relay
has reversed contacts. The new schematics
for modified relays are 9654A56, 9654A57,
9654A58.
7.0 ADJUSTMENTS AND
MAINTENANCE
The proper adjustments to insure correct operation of
this relay have been made at the factory. Upon
receipt of the relay, no customer adjustments, other
than those covered under "SETTINGS" (page 5),
should be required.
7.1 ACCEPTANCE CHECK
The following check is recommended to insure that
the relay is in proper working order.
7.1.1 Instantaneous Overcurrent Unit (I)
a. Contact Gap: The gap between the stationary
and moving contacts with the relay in the
de-energized position should be approximately
.020".
b. Minimum Trip Current: The normally-closed con-
tact of the directional unit should be blocked
open when checking the pick-up of the overcur-
rent unit.
The pick-up of the overcurrent unit can be
Types IRP, IRC and IRD
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