Storage – Howard Small Power User Manual

Page 6

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Document 2.4.54 Revision 0

July 2006

Small Power Substation Transformers



Transformer Storage

Transformers can be stored if properly prepared. It is

recommended that stored transformers be completely

assembled. Prior to storage, transformers should be

pressure tested according to the instructions on page 9

(Pre-energization Tests and Checklist)

. The gas space

above the insulating fluid should be pressurized with

dry nitrogen to a pressure between two and three PSIG.

This will prevent a negative internal pressure which

might draw moisture into the tank. Transformers not

designed for outdoor use must be stored indoors. If

the transformer is not completely assembled, separate

components and accessories should be stored in a

clean dry area in their original shipping containers.

Extended Storage

If the transformer is to be stored for an extended period

of time before being placed into service, it should be

placed on a firm level surface.

All space heaters (if supplied) in terminal chambers,

switch cabinets, control cabinets or other enclosures,

must be connected and energized at all times to control

moisture. If it is not practical to energize the control

cabinet space heater, desiccant packets may be used

to control moisture in control cabinets only. Desiccant

packets must be replaced periodically to maintain


It is recommended that the transformer be inspected

periodically as described below while it is in extended

storage. Results should be recorded and compared

with previous results to ensure that no damage or

change in condition has occurred.