09/11/2017
Observe and identify the schematic and
rating of the step down transformer to be
installed. For the large amperage type,
adequate circuit protection must be in
place before any wiring practice is
performed. The same holds true for the
smaller step down control transformer.
Remove all electrical power for the
transformer circuit. Be sure that both
sides of the circuit protection are in the
“off” position. When power is reapplied,
only one side can be energized at a time.
In other words you will only be energizing
the high side power feed of the
transformer first.
Remove the terminal connection box
cover placed at the lower side of the
transformer. Only the high amperage
types will have this enclosure, while lower
powered transformers will have an
exposed screw terminal. The bolt size will
vary by manufacturer and types of bolts
may vary from metric to SAE.
Know termination identification follows
for all step down transformers: H1, H2, H3
and H4 signify the high voltage side or
power feed end of the transformer. This
holds true regardless of the size of the
transformer. Interconnection of the
transformer will vary depending on the
manufacturer and voltage used for
feeding the transformer. Follow the
individual schematic for the type of
transformer to be installed.
Terminate the feed power wires first by
cutting the wires to length. If you are
using large wire lugs be sure to take into
consideration the length of the lug and
the amount of wire that can be inserted
into the female crimp area. The same
holds true for smaller wires on the smaller
control transformer for the use of eye
rings.
Strip back the outer insulating of the
wires with the pocketknife or wire
st*****rs.
Insert the eye ring or wire lug over the
bare copper wire and crimp the
connection device, using the appropriate-
size crimper, permanently to the wire.
Terminate the high side, high voltage of
the step down transformer. If the high
side terminals are bolts, be sure to follow
any torque requirements that are listed by
the manufacturer.
Terminate the low side, low voltage of
the transformer. Note these terminals will
be identified by X1, X2, X3 and X4. Again
follow the manufacturer's individual
schematics for that particular type of
transformer. Note that on small control
transformers there will only be an X1 and
X2. X1 is the power or “hot” side and X2 is
generally the grounding and neutral
portion of the low voltage.
Follow the same termination process for
the wires as described in step 7 and 8
above.
Terminate the small control transformer
for X1 and X2. X1 will go directly to the
control circuit after passing through a
small fuse that is rated for the circuit. X2
will be terminated not only to the neutral
side of the control circuit, but the
grounding safety as well. In other words,
the X2 side of the small control
transformer must be tied to the
grounding system of the electrical circuit.
Replace all covers on the transformer
and any enclosures that protect you from
electricity.
Apply the high voltage to the
transformer by switching on the feeder
power circuit.
Turn on the low side safety circuit
control.
Use a volt meter to test for proper
voltage on the step down side of the
transformer. It should be the same that is
listed on the specs tag provided by the
manufacturer.
Warnings
Follow all national, state and local
codes when installing any type of
electrical device.
Follow all manufacturer's
schematics when terminating step
down transformers--connections
may vary depending on applications
of the transformer.
