Current
technology yields a dry type transformer that is fully equal to
its mineral oil insulated counterpart. Dry types excel in
several important aspects. They can be located indoors without
the use of a fireproof vault or special catch basins, on roofs,
near buildings or anywhere within an industrial or commercial
building. Industry standards have been developed to give
users better yardsticks for specification and purchasing.
The latest standard, set forth by Underwriters Laboratories (UL),
encompasses those developed by IEEE, NEMA, ANSI, and various other
agencies. The Olsun medium voltage transformers are all
tested and built to these rigid specifications and assure the
purchaser of reliability, safety, and value. These Olsun
transformers are economical, can be used outdoors with little
concern for moisture in severe environments, and are environmentally
safe. The are available with overload capability of 33 percent
greater than nominal ratings. They offer the ideal alternative
to PCB insulated transformers.
Coil
Construction
There
are two types of coil construction methods in common use.
Barrel wound coils are the most economical and are acceptable
for voltages up to 5000 volts and where the BIL requirements do
not exceed 30KV. Above these parameters, field experience
has shown that barrel wound coils are very prone to the development
of corona. While somewhat more costly to manufacture, disc
wound coils practically eliminate the occurrence of corona and
the premature failures associated with this phenomenon.
Olsun uses the disc wound method exclusively on all transformers
above 5000 volts and/or 30 KV BIL.
Fan
Cooling
Olsun
offers all of its medium voltage transformers rated 300 KVA and
larger with an option of UL listed factory installed and wired
fan cooling systems. Fan cooling is useful in accommodating
unanticipated loads, short-term overload conditions, overloads
due to intermittent high ambient conditions, and similar situations.
Outdoor
Installations
Olsun
offers most the transformers in this publication UL listed and
labeled for NEMA-3R (weatherproof) application.
Nonsinusoidal
Loads
Olsun's U.L.
listed medium voltage transformers are available with appropriate
K-Raings for non-linear loads.
Sound
Levels
Since
dry type transformers are placed closer to the point of power
usage, and consequently closer to personnel, the level of noise
emission is more critical than for their oil-insulated counterparts.
The transformers listed in this bulletin are built to NEMA/ANSI
sound level standards, which yields an acceptable installation
in the majority of cases. Lower-than-standard sound levels
are available on special order. Olsun transformers are equipped
with vibration isolation pads between the core and coil and the
enclosure.
Basic
Impulse Levels (BIL)
Olsun
designs its transformers to conform to NEMA/ANSI BIL standards
at a minimum. Higher BIL levels are available on any Olsun
medium voltage transformers and are recommended where special
circumstances exist, such as feeder circuits exposed to lightning
or other voltage surges.
PCB
Replacement
Dry
type transformers are filling much of the gap left by the discontinuation
of PCB liquid filled transformers. They offer a better choice
than flame-retardant liquids. They are more fire resistant,
lighter in weight, easier to install, and more versatile in accommodating
existing bus connections and they do not require any special vaults
or catch basins. The result is a lower cost PCB replacement
project.
Enclosures
and Paint
Substation
style enclosures are built with a welded, fabricated steel base
to provide rigid dimensional integrity. Suitable for skidding
or rolling in any direction. The finish, a polyester power
paint, is applied through an electrostatic process, assuring complete
coverage. The paint is UL listed for outdoor application.
The standard color is ANSI 61 Grey, and other colors are available
on request.
Special
Enclosures
While
the enclosures shown will accommodate most dry type transformer
applications. Olsun recognizes the need for versatility
when applying dry type transformers for projects such as PCB replacement.
We can provide the exact configuration to fit your requirement
at minimal or no additional cost. Various termination schemes
are also available. For highly corrosive atmospheres, any
of the enclosures can be ordered in 304 or 316 stainless steel
or aluminum in standard powder coated system described above.
Accessories
Olsun
offers a wide range of accessories, factory mounted and wired,
too numerous to detail in this catalog. They include such
devices a primary surge arrestors, fused primary switches, circuit
breakers, current and potential transformers, meters and switches,
and air terminal chambers. |
HERE
for Features Page 
