The design project adopts the direct water supply method of stainless steel water tank. DN100 fire water supply main is led from the outlet pipe of the water spray pump in the transformer fire pump room to supply water to the foam spray system dedicated to the transformer. Similarly, DN25 foam concentrate pipe is led from the outlet pipe of the foam concentrate pump in the pump room to supply foam concentrate to the foam spray system dedicated to the transformer. The whole system is usually filled with foam stock solution in the foam solution pipeline in front of the proportioner.