Document 2.4.126, Revision 4
October 2017
18
Three-Phase Padmounted Distribution Transformers
The following procedure should be used to operate
a Bay-O-Net fuse device. Open both compartment
doors and engage the prop rods on each door to
latch them in the open position. On transformers
supplied with a hinged terminal compartment cover,
disengage the center security bolt and raise the
cover until the support arm latches in place.
Remove Fuse Holder
—The following procedure
should be used to draw the fuse holder out of the
Bay-O-Net housing.
1. Vent the transformer by operating the
pressure relief valve. Keep the valve open
until the sound of air venting can no longer
be heard.
2. Stand to one side of the Bay-O-Net device
being operated.
3. Attach a live-line tool to the holder eye.
4. Twist the live-line tool to unlock the fuse
holder.
5. Rotate the holder 90° clockwise in the
housing to break the seal between the
gasket and the housing.
6. Firmly and quickly pull the fuse holder out
about 8 to 10 inches to open the circuit.
Wait a few seconds while the fluid drains
back into the tank, and then completely
withdraw the fuse holder. Wipe the fuse
holder and cartridge to remove excess fluid.
7. If fluid continues to flow from the Bay-O-Net
device, operate the pressure relief device
again to vent pressure from the tank.
Replace Fuse Link
—Replace the fuse according to
the manufacturer’s instructions included with the
replacement fuse.
Re-Insert Fuse Holder
—Re-insert the fuse holder
using the following procedure.
1. Using a live-line tool attached to the eye of
the fuse holder, re-insert the holder firmly
into the Bay-O-Net housing.
2. Twist the locking handle, latching it to the
shoulder of the Bay-O-Net housing. Make
sure that the metal washer is positioned
tightly on the end of the Bay-O-Net housing.
3. Inspect the fuse holder carefully to make
sure it is fully seated and latched properly.
Dead-Break Dry-Well Canister Fuse
The dead-break dry-well canister is a fluid-tight,
single-pole, current-limiting fuse holder. It is
designed to be operated with a live-line tool (hot
stick or shotgun stick) and should not be operated
by hand. Dry-well canisters (one per phase) are
mounted on the transformer front panel in the high-
voltage section of the terminal compartment.
Dead-break dry-well canisters are not designed to
break load and must only be operated when the
transformer is de-energized. When specified, dry-
well canisters are mechanically interlocked with a
load-break switch to prevent removal of the fuses
while the transformer is energized.
The following describes proper operation of the
dead-break canister device.
Remove Fuse Holder
—The following procedures
should be used to remove the fuse holder.
1. Make sure the transformer is de-energized.
2. Attach a live-line tool to the hook eye.
3. Quickly pull the fuse holder assembly
completely from the housing.
Replace Fuse
—The fuse should be replaced using
the following procedure.
1. Unscrew the fuse from the fuse holder.
2. Replace with new fuse of equivalent rating
and characteristics.
3. Tightly screw the new fuse onto the fuse
holder.
DANGER
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW WILL RESULT IN DEATH OR SERIOUS
INJURY, AND DAMAGE TO THE EQUIPMENT.
• Do not operate a dead-break canister
fuse device while the transformer is
energized.
• When replacing a blown current-limiting
fuse, the transformer should be re-
energized from a remote location.
