System ISAS is designed for emergency cooling and extinguishing fires on transformers using a technology spraying fine dispersed water. Neutral gas generators are used to create the effect of fine water and water mist.
3. PROBLEM
Power utilities have installed power substations in their distribution grids to
accommodate the ever-increasing demand for dependable power with their rows
of large high voltage power transformers. Many precautions are taken to
safeguard them against failure because when all power fails, customers
complain, revenues are lost and medical emergencies can even happen.
One of the risks these large transformers are subjected to is fire. Although the
manufacturers of these oil filled transformers are building them with many
imbedded safety features, when they fail they often produce very large fires that
are very hard to extinguish and provoke environmental damages by the release of
thick black toxic smoke and spilling of transformer oil. This is why more and more
utilities are installing fire protection systems to protect their investment and to
prevent such fires. Containment curbs and runoff water catch basins are also
built around the transformers to prevent oil spills in case of problems.
When they are protected, most high voltage power transformers are with a
deluge sprinkler system and designers use NFPA-15 as a guide to design a
system that will cool off the transformer and eventually, extinguish the fire.
4. PROBLEM
Typical design calls for a grid of open type deluge/spray nozzles to be installed all
around the transformer. A typical system will use about 44 of them and will be
designed to spray about 500 gpm of water for a duration of one (1) hour.
That is a lot of water!
Example typical solution - use big amounts of water due
to flooding, cause collateral damage.
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5. PROBLEM
NFPA-850 for Power Plant Design goes even farther, requesting water spray
duration to last a full two (2) hours! But minimum provisions for drainage are
specified to be only large enough to contain the spill from the largest single
container of any flammable or combustible liquid in the area and for fixed fire
suppression systems operating for a minimum of 10 minutes!
A lot of power substations are located in remote areas, or on the outskirts of
towns where water is often not readily available in these large quantities. Water
reservoirs have to be built (often underground) to accommodate this large
demand. They require an initial investment that is fairly high for the utility
company and they also need regular maintenance, factors that are rarely included
in the fire protection contractor's proposal.
Even when water is available in these quantities, powerful fire pumps will be
needed to provide water at a sufficiently high pressure to achieve the goals of the
fire protection system. Infrastructure costs for the utility company rise rapidly, to
the point where some of them don't protect their transformers at all and will simply
provide passive protection measures such as firewalls.
7. SOLUTION
The Impulse New Technologies has developed a solution to these problems:
System ISAS is designed for emergency cooling and extinguishing fires on
transformers using a technology spraying fine dispersed water. Neutral gas
generators are used to create the effect of fine water and water mist.
video
9. GENERAL DESCRIPTION
The system consists of special tanks (ISAS module) which contain not less than
7,500 liters of water and built-in neutral gas generators. Spraying is carried out
through a fine water pulverization system installed around the transformer.
10. GENERAL DESCRIPTION
ISAS modules must be located in the immediate vicinity from the transformer (the
place is determined together with the customer). ISAS module can be located on
the ground or can be completely hidden underground to create space around the
transformer. The location of the module does not affect its work.
Each ISAS module can operate in two modes:
- Emergency cooling mode, water consumption rate is from 20 to 200 liters per
second
- Fire extinguishing mode, water consumption rate is 300 liters per second.
Due to the possibility of ISAS system to support the constant pressure in the
pipelines during its operation, the levels and locations of pipelines and modules
do not affect the efficiency of the system and can be defined by the Customer to
achieve maximum comfort during operation and maintenance of transformers.
ISAS system has no electric valves and other electrical actuators. It is completely
independent on external power sources and eliminates the possibility of failure of
mechanisms that are bound to external electrical interference as a result of an
accident on the transformer.
11. GENERAL DESCRIPTION
The system can be adapted for extinguishing with foam.
ISAS system is guaranteed to execute:
1. Start water feed in a fire extinguishing mode not exceeding the timeframe of
five seconds after the fire source determination in an automatic mode. This
timeframe will not exceed 3 seconds in case of a manual start-up.
2. Execute fire extinguishing or emergency cooling at any time during 10 years
the least at the absence of external sources of electricity and water.
3. Perform its work in case of global disaster or accident at the transformers
station and electrical network with a large number of electrical interference.
13. OPERATING PRINCÍPLE
The launch of the ISAS module in the automatic mode is conducted by sending a
low power electrical signal or manually by pressing a button or pulling the
operation ring.
In the automatic mode, the signal to start the system is sent by special
autonomous thermal sensors that automatically generate an electrical signal.
Sensors are 100% independent on external sources of electricity. The sensor is
completely protected from external electrical noise.
After starting the pressure generator, neutral gas (fire aerosol) is supplied into
the module case and this starts the displacement of water into fine sprays or into
the water pipes. The capacity of gas and pressure in the housing is automatically
maintained at the same level regardless of the amount of displaced water. For
emergency pressure release, each ISAS module contains pressure release
valves.
The pressure level in the system during operation shall be determined during the
module charging procedure with pressure generators and can be any in the range
from 0.2 to 2 Mpa.
After starting the module all water is displaced and pressure generator resource
is completely consumed. Recharging the module is conducted by trained
personnel of the customer and it takes less than one hour.