SC, SC-1, SV and SV-1 Relay
I.L. 41-766.1N
3
with tapped coils, as there is not sufficient space for
marking a scale for each tap. However, the scale
plate is supplied in order that a customer may mark
on it the individual relay setting or settings if desired.
3.0
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 four mounting holes
on the flange for semi-flush or by means of the rear
mounting stud or studs for projection mounting.
Either a mounting stud or the mounting screws may
be utilized for grounding the relay. The electrical con-
nections may be made directly to the terminals by
means of screws for steel panel mounting or to the
terminal studs furnished with the relay for thick panel
mounting. The terminal studs may be easily removed
or inserted by locking two nuts on the stud and then
turning the proper nut with a wrench.
For detailed FT case information refer to I.L. 41-076.
4.0
ADJUSTMENTS AND MAINTE-
NANCE
The proper adjustments to insure correct operation of
this relay have been made at the factory and should
not be disturbed after receipt by the customer.
If the
adjustments have been changed, the relay taken
apart for repairs, or if it is desired to check the adjust-
ments at regular maintenance periods, the instruc-
tions below should be followed.
All contacts should be cleaned periodically. A contact
burnisher Style 182A836H01 is recommended for
this purpose. The use of abrasive material for clean-
ing contacts is not recommended, because of the
danger of embedding small particles in the face of
the soft silver and thus impairing the contact.
Several factors may affect the dropout ratio of the
relay. Whatever affects the ratio does so because
either the dropout or pickup or both are affected.
Obviously, incorrect assembly or interchange of
parts, such as the use of the SC plunger with the SV
core tube, will alter the electrical characteristics.
However, the factor most likely to be encountered in
service is friction. This may be due to dirt or foreign
material between the plunger shaft and its bearings,
to excessive pressure of the indicator screen on the
indicator, or to leads so mis-shaped that they tend to
rotate or tilt the moving contact insulation plate with
appreciable force.
In order to remove the plunger and shaft assembly, it
is necessary to remove the setscrew and nut at the
top of the shaft. The spool-shaped bushing assem-
bled on the upper end of the plunger shaft has a por-
tion of its center section machined off so that the
shaft is exposed at this point and can be prevented
from turning by gripping shaft and bushing with a pair
of long-nose pliers while removing the set screw and
nut. Then by pressing down with the fingers on the
upper end of the shaft, the lower split sleeve which
retains the lower bearing will be forced out of the
threaded tube, the bearing will drop out freely, and
the upper split sleeve will be forced out far enough to
permit grasping it for removal. The shaft and plunger
assembly then can be removed.
The shaft and plunger assembly should be handled
carefully to avoid bending the shaft or damaging the
bearing surfaces.
The shaft should never be gripped
on it upper bearing surface, below the spool-shaped
bushing
, when loosening the nut and setscrew, as
this would almost certainly damage the bearing sur-
face. The shaft bearing surfaces should not be
cleaned or polished with any abrasive material, as
the abrasive particles might become imbedded in the
shaft and cause difficulty later. The plunger shaft and
bearings may be cleaned by wiping them carefully
with a clean, lint-less cloth. Use no lubricant on the
plunger shaft or bearings when re-assembling the
relay, since this will eventually become gummy and
prevent proper operation. It is recommended that the
shaft be cleaned at intervals of approximately two
years. When replacing the lower bearing and the split
sleeves, the shorter sleeve (assembled below the
bearing) should be pushed in until it is flush with the
end of the threaded tube.
The mounting holes in the operation indicator screen
are slotted so that its position can be adjusted. For
relays in which the moving contacts are not latched
in the operated position, the screen should be so
located that the indicator positively enters the screen
opening when the contacts barely touch. For latch-
type relays, the screen should be so located that
good contact is still obtained when the relay is de-
