page_32

< previous page | page_32 | next page >

Page 32

| Figure 2-13 Main features of an oil conservator. |

| the transformer tank. In some instances, pressure relays are installed to give indication of a rise in pressure within the tank. In as much as deteriorating insulation often gives off heat and gas, such indication may also be a sign of approaching insulation failure. |

| Increased Cooling |

| In order to improve the cooling effect, the surface of the enclosing tank exposed to the surrounding air is increased by corrugating the flat sides or by adding fins to them. Sometimes, radiators or tubes are attached to the tanks so that the hot oil on top may circulate through them, entering from the top and returning to the tank at the bottom; in effect, these radiators add still more cooling surface and improve the circulatory effects of the oil (Fig. 2-14). |

| The effectiveness of the cooling system may be increased by forcing a current of air to blow away the heated air adjacent to the heated surfaces and replacing it with cool air in rapid motion. The air blast may be directed against the transformer enclosure and radiating surfaces, or may be forced through air ducts contained within the transformers (Fig. 2-15). |

| The effectiveness of cooling systems may also be increased by forced circulation of the oil by means of a pump (Fig. 2-16 on page 34). The oil may be circulated from the bottom of the tank to the top through the pipes or radiators connected to the tank. It may also be circulated from the tank to a remote and separate cooling device and back to the transformer. |

| Additional cooling of the transformer oil, in very large units, is sometimes obtained by water cooling pipes situated within the tank of the transformer. |

| Depending on circumstances and requirements, combinations of the forced air, forced oil, and water cooling processes may be used. |

< previous page | page_32 | next page >