Howard HI-102 Overhead Transformer - Manual (Page 10)

Document 2.4.95, Revision 0
May. 2013
10
Fluid-Filled Overhead Distribution Transformers
When specified by the user, base skids are provided
for mounting the transformer on a solid, level
surface, rather than on a pole. The factory may
elect to provide skids for transformers whose weight
exceeds the capability of pole-mounting brackets.
The mounting surface must be rated to support the
weight of the completely assembled transformer.
Refer to the transformer nameplate for the weight of
the transformer.
Grounding
The transformer must be permanently and effectively
grounded according to applicable local and
national codes. Ground the transformer by using
the ground pads or nuts provided on the tank. Do
not use hanger brackets or any other parts of the
transformer for ground connections. A proper low-
resistance ground connection is necessary for safe
operation. Connect all available neutrals to the
system neutrals.
▲
! WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY, AND COULD ALSO RESULT
IN DAMAGE TO THE EQUIPMENT .
The transformer must be permanently and
effectively grounded at all times.
High-Voltage and Low-Voltage Connections
The transformer nameplate illustrates the internal
wiring and external identification of each bushing.
The transformer must be connected and operated
as indicated on the nameplate. High-voltage and
low-voltage bushings are provided with terminals
as specified by IEEE standards for overhead
transformers, or as specified by the customer.
Terminals are usually suitable for connection to
either aluminum or copper conductors.
Before making high-voltage and low-voltage line
connections, check to make sure that all mating
connector surfaces are clean and smooth.
Connections must be tightened adequately to
prevent overheating and possible failure of the
connection. Refer to the nominal torque guidelines
contained in Table 3. Avoid excessive cantilever
loads on bushings, otherwise bushing or gasket
damage may result.
Reconfiguring the Internal Low-Voltage Connections
Unless otherwise specified by the user, overhead
transformers with three low-voltage bushings are
shipped from the factory with the internal low-
voltage winding configured for the E/2E connection
(for instance, 120/240 or 240/480 Volts). If the
transformer must be reconfigured for operation
at E Volts (for instance, 120 or 240 Volts), the
transformer cover must be removed and the low-
voltage leads reconnected in parallel. Connections
must be tightened appropriately to prevent
overheating and possible failure of the connection.
Make sure the internal low-voltage leads are
insulated and that they do not touch the tank, each
other or any other surface. Refer to “Opening the
Transformer Tank” for instructions.