25-06-2013, 12:33 PM
STUDY AND DESIGN OF POWER PLANT TRANSFORMER EXPLOSION AND
FIRE PREVENTION
STUDY AND DESIGN.pdf (Size: 224.42 KB / Downloads: 50)
INTRODUCTION
The study of the “Power Plants
Transformer Explosion and Fire
Prevention” started on request of a large
western U.S. utility which had experienced
a severe hydro power plant transformer
explosion. This incident occurred
underground, destroying one transformer
and damaging another nearby. This now
common event lead to a four-month total
power plant shutdown and 10 months
unit unavailability.
Several on-line monitoring systems
were installed on the transformers to try
and anticipate another failure. The major
concern was that this monitoring might
not prevent an explosion, so SERGI was
contacted to avoid a second catastrophic
incident, should another transformer fail.
SERGI specializes in transformer
vessel explosion and fire prevention. The
Design Department has conducted
research since 1995 to understand and
quantify the energetic transfer phenomenon
that takes place within a vessel during
a short circuit, which has led to the
Magneto-Thermo-Hydrodynamic model
(MTH) development.
SERGI decided to study the prevention
of power plant transformer explosions,
because of the harsh arcing that
can occur. During short-circuit, transformer
faults are fed for seconds due to
the generator inertia. Therefore, designing
a system able to prevent a power
plant transformer explosion fully satisfies
the explosion prevention of any other
kind of incident for transmission or distribution
transformers.
The purpose of these studies was to
determine an efficient way to depressurize
the transformer vessel during and
after these short-circuit conditions in
order to avoid explosion and the resulting
oil fire. SERGI extensively investigated
the event, simulating causes, calculating
the transformer vessel pressure rise, and
proposed a suitable solution. The aim
was therefore to design a system capable
of preventing the worst-case scenario in
order to satisfy the prevention of any
other kind of incident.