Transforming future trends
into innovations
Siemens bullet resistant transformers and reactors
Why bullet resistant?
Power transformers are essential in
the effective and reliable transmission and distribution of electricity.
Serving as critical nodes, these pieces of equipment have been engineered over decades to withstand
operational risks such as lightning
strikes, severe weather events, seismic activity and network power
fluctuations. However,despite their
complexity, transformers are vulnerable to malicious attacks, especially
those carried out with high-powered ballistics.
Siemens has taken significant steps
to investigate, test and develop new
materials and designs, which allow
our transformers and reactors to
withstand ballistic attacks, ensuring
their physical security.
Alarming attack on U.S. power station
On April 16, 2013, an electric power station in Metcalf, California, was attacked
by snipers with at least one high-powered
rifle. The assailants surgically knocked out
17 giant transformers within 20 minutes.
These transformers funneled electric
power to Silicon Valley, home to many of
the world’s largest technology corporations and roughly four million people.
Fortunately, power could be rerouted
around the damaged site, and other power plants in the area were called to produce more energy in order to avoid a
blackout. It took almost a month before
the substation was able to resume normal operation.
Although most well publicized, the
Metcalf attack was not an isolated incident. According to an analysis by the
Wall Street Journal, there were 274 cases
of vandalism or deliberate damage to
power stations between 2012 and 2014
in the United States alone.1)
Due to significant capital expenditure requirements and extended lead-times,
best practice to ensure the reliable operation of critical transformers and reactors
is to protect them from malicious attacks.
Siemens research and development
In order to increase network safety and
reliability, Siemens has investigated ways
to produce bullet resistant transformers
and reactors. These investigations have
resulted in the first transformer and reactor protection unit of its kind. Mitigating
the threat of high-powered ballistics, the
unit offers a comprehensive solution and
can be retrofitted onto equipment currently in operation.
1)
Smith, Rebecca. “Assault on California Power Station
Raises Alarm on Potential for Terrorism.”
[published in Wall Street Journal]
siemens.com/transformers
Standards and
classifications
Weapons calibers are classified
according to different standards.
In Europe, this is the VPAM APR2006
standard. In the U.S., the UL752
standard is applied.
The VPAM Class 13, .50 BMG M2 AP
round is the highest class of rifle
projectile considered by VPAM and
represents the likely maximum
threat from a ballistic attack.
Materials testing
Above: A 10 mm S335 steel sheet –
representing a standard transformer
tank wall – penetrated by a VPAM
Class 7, .308 Winchester lead core
projectile.
Above: The reverse of an 8-inch
reinforced concrete wall penetrated
by a VPAM Class 13, .50 BMG M2 AP
projectile.
Design concept
Our transformer and reactor protection
unit has been adapted from external noise
reduction systems. The bottom-up design
consists of tank-mounted panels, negating
the need for foundations, which protects
the tank, cooling equipment, conservator,
turrets and the bottom of the bushings. An
illustration of the transformer protection
unit is seen below.
Installation advantages
The unit consists of bullet resistant
panels that are supported by steel brackets attached directly to the transformer
or reactor tank wall. Such a setup allows
foreasy installation of the system onto
critical pieces of equipment and permits
the design to be retrofitted onto transformers and reactors currently in operation.
We are also able to replace porcelain
bushings with polymer or composite RIP
oilless-type bushings so that even if the
polymer insulator is penetrated, catastrophic failure will not lead to ignition of
the oil.
The figure above depicts the support
structure connecting the tank to the bullet resistant panels.
Bullet resistance
Initial tests illustrated the vulnerability of
transformer tanks to ballistic attacks. Included in the images to the left are the
results from a VPAM Class 7, .308 Winchester lead core round penetrating a
10mm S335 steel plate. This represents
an easily accessible standard rifle bullet
and a typical transformer tank wall.
Further results from testing have shown
the protection unit is capable of withstanding VPAM Class 13, .50 BMG M2
AP projectiles. The .50 BMG projectile is
the most powerful cartridge not considered a destructive device under the
National Firearms Act enforced by the US
Department of Justice and represents the
maximum likely threat from a ballistics
attack.2)
Operating efficiencies
Rigidly mounting the system directly onto
the tank minimises the space required to
protect vital transformers or reactors
while the bullet resistant panels may be
adapted to reduce acoustic emissions
during operation. We have also ensuredsufficient accessibility to carry out all
maintenance works on the equipment.
Furthermore, the offset of the panels
from the tank allows the movement of
air over external cooling equipment such
as radiators and fans, offering protection
to these components while ensuring
efficient operation.
Published by and Copyright © 2016:
Siemens AG
Energy Management Division
Freyeslebenstrasse 1
91058 Erlangen, Germany
Above: A VPAM Class 13, .50 BMG
M2 AP round – representing the
maximum likely ballistics threat –
being reflected by the Siemens
protection system.
2)
ason, Martin (2015) »AR Platforms Firearms &
M
Calibers.« First $trike Publishing, S. 210
Siemens AG
Energy Management Division
Transformers
Katzwanger Strasse 150
90461 Nuremberg, Germany
siemens.com/transformers