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switches (see Figure 16) between terminals
8-9
and 12-13 remain closed with the chassis
out to prevent open circuiting the current
transformers when the current test switches
are closed.
When the chassis is to be put back in the
case the above procedure is to be followed
in the reversed order.
CAUTION: Be sure to operate the cam latches
into their original horizontal position before at
tempting to replace cover. Failure to do so may
crack the cover.
ELECTRICAL CIRCUITS
Each terminal in the base connects through
a test switch to the relay units in the chassis
as shown on the internal schematic diagram
Fig. 3. The relay terminals are identified
by numbers marked on the outside of the
case. The test switch positions are identified
by numbers marked on the molded blocks.
The potential and control circuits through
the relay are disconnected from the external
circuit by opening the associated test
switches. A current test switch is illtts
trated in Figure 15. Opening both current
test switches short-circuits the current
transformer secondary and disconnects one
side of the relay circuit but leaves the other
side of the relay circuit connected to the
external circuit through the current test
jack jaws. This circuit can be isolated by
inserting an ammeter test plug S#ll64047
SWITCH BLADE JAW
CLIP LEAD LUG
AMMETER
TEST PlUG
SWITCH BLADE HINGE
Fig. 14
-
Ammeter Test Plug in Testing Positions
(without external connections), or by insert
ing ten-circuit test plugs S#1164046.
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 S#116404 7 can be in
serted in the current test jaws after opening
the knife-blade switch to check the current
through the relay, as shown in Fig. 14. This
plug consists of two conducting strips sep
arated by an insulating strip. The ammeter
is connected to these strips by terminal
screws and the
1
eads are carried out through
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, the
ten circuit test plug S#1164046 can be in
serted in the contact jaws, per Figure 17.
This connects the relay units to a set of
KNIFE BLADE
SHORT CIRCUITING SPRING
"'"'\
STRAP CONNECTION
10
TERMINALS FOR
EXTERNAL CONNECTIONS
SWITCH BLADE
MOLDED INSULATION BLOCK
Fig. 15- Short Circuiting Switch
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