TYPE HQS RELAY
letters can be seen when the chassis is re
moved from the case.
The potential and control circuits thru the
relay are disconnected from the external cir
cuit
by opening the associated test switches.
Opening the current test switch short-circuits
the current
transformer secondary and dis
connects one side of the relay coil but leaves
the other side of the coil connected to the
external circuit thru the current test jack
jaws.
This circuit can be isolated by in
serting the current test plug (without ex
ternal connections),
by inserting the ten
circuit test plug, or by inserting a piece of
insulating material approximately 1/32" thick
into
the
current test
jack
jaws. Both
switches of the current test switch pair must
be open when using the current test plug or
insulating material in this manner to short
circuit the current; transformer secondary.
A cover operated switch can be supplied with
its contacts wired in series with the
trip
circuit.
This switch opens the trip circuit
when the cover is removed. This switch can be
added to the existing type
FT
cases at any
time.
Testing
The relays can be tested in service, in the
case but with the external circuits isolated
or out of the case as follows:
Testing in Service
The ammeter test plug can be inserted in the
current
test
jaws after opening the knife
blade switch to check the current thru the re
lay.
This plug consists of two conducting
strips separated by an insulating strip. The
ammeter is connected to these strips by termi
nal
screws and the leads are carried out thru
holes in the back of the insulated handle.
Voltages
between the potential circuits can
be measured
conveniently by clamping #2 clip
leads on the projecting clip lead lug on
the
contact jaw.
Testing in Case
With all blades in the full open position,
4
the ten circuit test plug can be inserted in
the
contact
jaws.
This connects the relay
elements
to
a set of binding posts and com
pletely isolates the relay circuits from the
external connections by means of an insulating
barrier on the plug. The external test cir
cuits are connected to these binding posts.
The plug is inserted in the bottom test jaws
with
the binding posts up and in the top test
switch jaws with the binding posts down.
The external
test circuits may be made to
the relay elements by #2 test clip leads in
stead of
the test plug. When connecting an
external test circuit to the current elements
using clip leads, care should be taken to see
that
the current test jack jaws are open
so
that the relay is completely isolated from the
external circuits.
Suggested means for iso
lating this circuit are outlined above under
"Electrical Circuits."
Testing out of Case
With the chassis removed from the base, re
lay
elements may
be tested by·using the ten
circuit test plug or by #2 test clip leads as
described above. The factory calibration
is
made with the chassis in the case and removing
the chassis from the case will change
the
calibration values by a small percentage.
It
is recommended that the relay be checked in
position as a final check on calibration.
INSTALLATION
The relays should be mounted on switchboard
panels or their equivalent in a location free
from
dirt,
moisture, excessive vibration and
heat. Mount the relay vertically by means of
the two mounting studs. Either of these studs
may
be utilized for grounding the relay. The
electrical connections may be made direct to
the terminals by means of screws for
steel
panel mounting or to terminal studs furnished
with
the relay for
ebony-asbestos or slate
panel mounting. The terminal studs may be
easily removed or inserted by locking two nuts
on the studs and then turning the proper nut
with a wrench.
The external connections of both the relay
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