Speedfax 2017

Buck-Boost Transformers
Single Phase, Three Phase
Typical Connection Diagrams
If you are using this unit as an auto
transformer to buck (lower) or boost
(raise) the voltage by a 12 to 48 volts use
the information on pages 8-22 to 8-24 to
select the proper wiring diagram.
Note: HV= Higher Voltage, LV= Lower
Voltage when bucking and boosting.
If you are using this unit as an isolation
transformer with a primary of 120 or
240 or 480 volts and the secondary of
12/24, 16/32, or 24/48 (depending on the
model) use the wiring diagram located
on the inside of the cover to the wiring
compartment.
Low-voltage Applications:
By using the “Standard Step-down
Application” diagram at left, buck boost
transformers will convert 120V or 240V to
12, 24, 16 or 32 volts and 240V or 480V to
24 or 48 volts without affecting the nameplate
kVA rating of the transformer. Buck
boost transformers used in this type of
application will become isolation or insulating
type transformers.
Single Phase
Diagram 1
Diagram 2
(Standard Step-down Application)*
Diagram 3
Diagram 4
8 TRANSFORMERS
Note:
•Inputs and Outputs may be reversed; kVA capacity
remains constant. Exception: Cannot use 3-wire input
with 4-wire output to form a neutral and does not
apply to standard step-down applications.
•Refer to NEC 450-4 for overcurrent protection of an
autotransformer.
•All applications are suitable for 60Hz only,
contact factory for 50Hz information.
Siemens Industry, Inc. SPEEDFAX Product Catalog 8-25