transforme protection

AUTOMATIC H. V. WATER SPRAY SYSTEM FOR TRANSFORMER PROTECTION

General :

High Velocity Water Spray Systems (H.V.W.S.S.) are installed to extinguish fires involving liquids with flash points of 650 c (1500 f) or higher. Three principles of extinguishment are employed in the system – emulsification, cooling and smothering. the result of applying these principles is to extinguish the fire within a few seconds.

THIS SYSTEM IS MOSTLY USED FOR THE PROTECTION OF THE FOLLOWING 

  1. transformers, oil filled equipment of power stations.
  2. turbo-alternators and other
  3. oil fired boiler rooms, oil quenching tanks.

Transformer protection shall contemplate on essentially complete impingement on all exterior surfaces except the underside, which may be protected by horizontal projection.

Transformer present particular design problems for water spray protection, primarily due to their irregular shape and necessary clearances to be provided for the high voltage equipment. There is much more interference with the water flow on the sides of the transformer than at their top. Due to this reason the protection usually involves a large number of small capacity projectors than a few bigger ones. Often it will be necessary to put more water on the transformer than required to achieve complete impingement and total envelopment.

Also, in the case of transformers where oil has been stored in condensate tank over transformer which is used for cooling purpose. This oil is hot and there are chances of leakage of oil and due to there are cables around and below transformer when this hot oil comes in contact of them the fire starts. Also, due to cables the fire spreading is very fast and hence to control this type of fire it has been proven that H. V. Water Spray system is best major to control and extinguish the fire.

Also, in the case of transformers where oil has been stored in condensate tank over transformer which is used for cooling purpose. This oil is hot and there are chances of leakage of oil and due to there are cables around and below transformer when this hot oil comes in contact of them the fire starts. Also, due to cables the fire spreading is very fast and hence to control this type of fire it has been proven that H. V. Water Spray system is best major to control and extinguish the fire.

All system components shall be so located as to maintain minimum clearances from live parts.

“Clearance” is the air distance between water spray equipment including piping nozzles and detectors and un-insulated live electrical components at other than ground potential. The minimum clearance is 900 mm under normal conditions. During the operation of  water spray system, they are intended for use as safe.

OPERATION DETAILS OF WATER SPRAY SYSTEM

A deluge system (automatic high velocity water spray system) is a fixed fire protection system, which totally floods an area with pressurized water through a system of piping with open nozzles & sprinklers. The system piping is empty until the controlling valve is activated by a hydraulic or other types of release systems. Deluge valve has an inlet, outlet & priming chamber. The inlet & outlet are separated from the priming chamber by the valve chamber & diaphragm. In the” set “position, pressure is applied to the priming chamber through a restricted prime line. The pressure is trapped in the priming chamber & holds the clapper on the seat due to the differential area. When the pressure is released from priming chamber faster than it is supplied through the restricted priming chamber line, the clapper move & allow the inlet water supply to flow through the outlet into the system and associated alarm device.

Water spray system are installed to control fire & to provide cooling &/or exposure protection to such risks where extinguisher is always not possible or even desirable e.g. fire involving flammable fluids having flash points below 650 c (1500 f) as per cl.no.4.1.1.(tac -1998 rule for water spray system ).

In case of fire the quartzoid bulb sprinkler shall burst at rated temperature due to heat which allow water in the detection pipe to drain out and in process allow the  deluge valve to open fully. As soon as the deluge valve opens the water shall flow through the piping to flow water to all water spray nozzles mounted on the piping around the transformer. The water shall be sprayed in hollow conical spray pattern to cover entire area of the transformer so that the fire on the transformer shall cool due to emulsification as well as fire get extinguish due to cutting off oxygen due to coverage pattern of the nozzle.

The fire shall be control and extinguished with the help of the H. V. water spray system.  The indication of operation of the system shall be available on the control panel with alarming siren. 

ADVANTAGES OF H. V. SPRAY SYSTEM

  1. Entire Transformer is flooded with water, which extinguish fire at earliest as well as avoid further destruction.
  2. Very quick in response.
  3. The fire losses is kept low as the area near fire get cooling due to water and so chances of spreading fire is negligible.