4) Trip Free Operation
The linkage (Figure 1, #19 & 20 &
Figure 2, #21) is mechanically trip free in
any location on the closing stroke. This
means that energization of the trip coil
while closing after the auxiliary switch
contacts change position will rotate the
trip latch (Figure 1, #18) clockwise and
permit the ground and test device to
open. The linkage will reset as a normal
open operation, the flywheel will complete
its rotation, and the closing spring will
recharge as described under SPRING
CHARGING.
d. I
nterlockS
1) Closing Spring Discharge Interlock
The function of the closing spring discharge
interlock is to prevent racking into or out
of metal-clad switchgear a ground and test
device with the closing spring charged.
This is accomplished by a roller on the right
hand side of the mechanism which contacts
the racking mechanism and discharges the
closing spring except if the ground and test
device is in the “Disconnect/Test” position
or the “Connect” position in the
metal-clad switchgear. This interlock also
opens the CL/MS switch in the motor
charging circuit to prevent charging the
closing springs when the ground and test
device is between the “Disconnect/Test”
or “Connect” position in the metal-clad
switchgear.
2) Negative Trip Interlock
The function of the negative trip interlock
is to disengage the trip latch from the trip
latch roller thereby preventing a closing
operation. The interlock also opens the
latch checking switch (52LCS) in the
closing circuit thereby removing the close
circuit power. The negative interlock is in
operation while the ground and test
device is moving between the
“Disconnect/Test” position and the
“Connect” position. A redundant negative
trip interlock is a backup to the negative
trip interlock and provides the same
function except it operates only near the
connect position.
3) Positive Interlock
The positive interlock operates to prevent
the racking of a ground and test device
that is closed. A linkage connected to the
horizontal connecting bar extends a detent
bar out from the side of the mechanism
frame when it is in the closed position. If
the closed ground and test device is in the
“Connect” or “Disconnect/Test” position
in the metal-clad switchgear the detent
bar locks into the racking mechanism to
prevent access to the hex section of the jack
screw. The positive interlock also prevents
the lift truck from picking up a closed
ground and test device.
4) Closing Spring Gag Interlock
The closing spring gag interlock
(Figure 5) is provided on the ground and
test device to prevent a ground and test
device that has a gagged closing spring
from entering the metal-clad switchgear
unit. This is accomplished by projecting a
lever out of the left side of the mechanism
when the closing spring is gagged.
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Equipment Description
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100
