Howard HI-104 Single-Phase Pad Transformer - Manual (Page 16)

Document 2.4.96, Revision 0
March, 2013
16
Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers
Hot-Stick Operable Devices
Some devices such as draw-out expulsion fuses,
dry-well canister fuses, dead-front high-voltage elbow
terminations, rotary load-break switches and auto-
matic pressure relief valves are designed to be oper-
ated with a live-line tool (hot stick or shotgun stick).
Do not attempt to operate by hand any device that is
designed to be operated with a live-line tool. Inspect,
test and operate the live-line tool according to the in-
structions provided by the live-line tool manufacturer.
Tap Changer
The de-energized tap changer may be used to adjust
the voltage ratio of a transformer while it is de-ener-
gized. It is intended to allow adjustment of the out-
put (secondary) voltage to the rated value. Do not
use the tap changer to alter the output voltage to any
voltage other than that indicated on the transformer
nameplate. If the tap changer is set to provide an
output voltage other than the rated secondary volt-
age, improper transformer operation could occur.
▲
! WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY, AND COULD ALSO RESULT
IN DAMAGE TO THE EQUIPMENT.
• Do not operate a de-energized tap changer
unless the transformer is totally de-energized.
• Do not re-energize the transformer unless the
tap changer handle or cap is secured in the
desired position.
Tap changers usually have five or seven tap positions
as indicated on the tap changer dial plate and the
transformer nameplate. A locking screw is provided
on the operating handle to lock the tap changer into
position and prevent accidental operation.
Prior to operating the tap changer on a de-energized
transformer, disengage the locking screw and then
rotate the handle to the desired tap position. Never
operate a tap changer while the transformer is en-
ergized. Do not re-energize the transformer until the
tap changer is set to the desired tap position, and
the locking screw has been engaged.
The transformer is usually shipped from the factory
with the tap changer set to the rated voltage posi-
tion, unless otherwise specified by the customer.
Always check the tap changer position to make sure
it is set correctly.
Multiple-Voltage Switch
Transformers designed with multiple high-voltage
windings (dual-voltage or triple-voltage transformers)
are provided with a de-energized multiple-voltage
switch. The switch, if provided, will be indicated on
the transformer nameplate.
The transformer must be completely de-energized
before operating the multiple-voltage switch. Unless
otherwise specified, multiple-voltage transformers
are shipped from the factory with the multiple-volt-
age switch set to the highest voltage position.
▲
! WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY, AND COULD ALSO RESULT
IN DAMAGE TO THE EQUIPMENT.
• Do not operate a de-energized multiple-volt-
age switch unless the transformer is com-
pletely de-energized.
• Do not re-energize the transformer unless
the multiple-voltage switch handle or cap is
secured in the desired position.
Load-Break Switch
The optional rotary load-break switch is located
inside the terminal compartment. The switch can
be designed as a two-position ON-OFF switch, or a
three- or four-position sectionalizing switch. Switch
positions are marked on the transformer front panel
and shown on the nameplate diagram. Load-break
switches are designed to be operated with a live-line
tool (hot stick or shotgun stick) and should not be
operated by hand.
The two-position load-break switch is operated by
inserting the live-line tool into the operating handle
and rotating the switch to either the ON or OFF posi-
tion. The three-position or four-position load-break
switch is operated by inserting the live-line tool in
the index plate and moving the plate over the peg