Howard HI-104 Single-Phase Pad Transformer - Manual (Page 7)

Document 2.4.96, Revision 0
March, 2013
7
Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers
Before unloading the transformer, the following
checks should be performed:
1. Read the serial number on the transformer
nameplate and make sure it matches
the serial number listed on the shipping
documents. Also, check the nameplate
for kVA rating, high-voltage rating, low-
voltage rating, impedance and other design
characteristics, and make sure they comply
with the specifications.
2. Check shipping documents to make sure
the shipment is complete, including all listed
accessories and hardware. Be aware that
additional items may arrive on separate
pallets. Claims for shortages or errors
must be noted on the shipping documents
and reported immediately to the Howard
Industries Transformer Division. Failure
to make a timely claim will constitute
unqualified acceptance and a waiver of all
such claims by the purchaser.
3. The tank vacuum/pressure gauge, when
provided, may indicate a positive or negative
reading when the transformer is received,
depending on the relative temperatures of
the fluid and ambient air. A rising or falling
reading that varies over time with ambient
temperature indicates that the transformer
tank is sealed effectively. If the vacuum/
pressure gauge shows a constant zero
reading, this indicates the possibility of a
tank leak. If this occurs, the tank should be
checked carefully for leaks as indicated in
the following step.
4. Check the tank for indication of fluid leaks,
looking carefully at weld seams, bushings,
gauges, valves and all other tank fittings. If
suspicious indications are found, investigate
thoroughly to determine if a leak does
exist on the transformer. Indications of a
leak can sometimes be residual fluid that
was not cleaned during the manufacturing
process and not an actual leak. In many
cases a small pinhole tank leak or leak
from a bushing, gauge, valve or other fitting
can be easily repaired on site. Refer to
the “Maintenance and Repair” section for
information about the repair of fluid leaks.
5. Check for external damage including dents
or scratches on the tank walls, radiators and
terminal compartment. Dents and scratches
can often be repaired on site using simple
touch-up procedures. If touch-up painting
is performed, do not remove or obscure
any warning labels, instructional labels or
nameplates.
6. Check for broken, cracked, or damaged
bushings, gauges, valves and other fittings
and accessories.
7. Check for missing or damaged component
parts and for packages that shipped
separately from the transformer.
Fluid Level
The transformer is shipped from the factory with
insulating fluid filled to the proper level. Before
energizing the transformer, verify proper fluid level
by observing the fluid level gauge, if provided. The
fluid level gauge pointer should be between the
“High” and “Low” marks. For transformers provided
with a fluid sight plug, the fluid level can be directly
observed if it is within acceptable range. If the
transformer does not have a fluid level gauge or sight
plug, the fluid level can be checked by removing
the liquid level plug located at the 25°C mark. Prior
to removing the fill plug, relieve tank pressure by
operating the PRV, being careful to avoid any hot
fluid that might be expelled from the valve. Exercise
caution when checking the fluid level using the
fluid level plug, as the fluid may spill out and may
be extremely hot. When reinstalling the fill plug,
apply a suitable sealing compound to the threads to
ensure a proper seal. When checking the fluid level,
be aware that the level will vary as a function of fluid
temperature.
A transformer found to have a low fluid level should
be checked for potential leaks and filled to the
proper level with the same type of liquid as that
specified on the transformer nameplate. Refer to
“Filling with Fluid.”