Abstract: The integrity of the stock fixed extinguishing system of the UHV substation is an important prerequisite to realize its extinguishing ability. First, the fire resistance status of fire pipe network of water spray extinguishing system for the UHV sub station is defined by comparing fire resistance test methods of fire pipe specified in existing standards and combining with true fire extinguishing test data of UHV transformer. Secondly, the principle of gas burner is used to design the test ignition source. The temperature of the test ignition source is in good agreement with the temperature measured in the fire extinguishing test of the full- size UHV transformer model. Therefore, using the test ignition source to carry out the fire resistant test can be more in line with the actual possible heating situation. Finally, through the comparative test, some suggestions to improve the fire resistance of water spray fire pipe network are proposed, which can provide reference for the actual engineering reconstruction and construction.

Key words: UHV, transformer, water spray extinguishing system, fire pipe network, fire resistant