电机学简易课件(2).pdf

Structure of Giant PowerTransformer1.2 Basic Components of A Power Transformer Iron core.Winding Oil Tank and Cooling Device Tap changer Insulating BushCore and Winding AssemblyAccessories Protector1.2.1 Iron CoreQMain magnetic circuit of the transformer.;unctio:smSilicon steel sheet of 0.35 to 0.5 mm thickness,the two surfaces of which are coated by insulation varnish.Most of power transformers adopts core type structure.Require jnentsJFastened;must be grounded at one point.1.2.1 Iron CoreQIron core1.2.1 Iron CoreIron coreIron core1.2.2 Winding QFunctiorCircuit part of the transformer.aterialCopper conductor or the aluminum conductor wrapped with insulation paper.Low-voltage winding and high-voltage winding are respectively connected with the methods of Y connection or delta connection,which is denoted by a vector group symbol.onnect ionThe tap of high-voltage winding connects the tap changer,so that ifs easy to regulate voltage.pHHH 即iMi 1MHI i I；：i;I i 1!*.，）llllllllliSHWBSM;1W1.2.2 Winding QWinding1.2.2 Winding QWinding1.2.3 Transformer Oil QFunctiorIncrease the insulating strength of the winding;convenient for heat dissipation.equira mentsjMust be characterized by high insulation performance and high ignition point,low viscosity,low content of water and impurities.InspectObserve oil color,level,temperature and whether there is oil leak phenomenon.1.2.3 Transformer Oil0Transformer Oil1.2.4 Oil Tank of the Transformer and Other Accessories0Oil TankBell TypeSuspended typeAdopted by the large transformerAdopted by the distribution transformer1.2.4 Oil Tank of the Transformer and Other Accessories(1)Bell Type1.2.4 Oil Tank of the Transformer and Other Accessories0(2)Suspended type1.2.4 Oil Tank of the Transformer and Other Accessories(2)Suspended type(2)Suspended type1.2.4 Oil Tank of the Transformer and Other AccessoriesConservator TankBuffering and reducing contact area of oil with outside air.7unctio:FormInspect1.Observe,The conservator tank and the outside word are connected by the breather(small power transformer).The air bag in the conservator tank and the outside word are connected by the breather(large power transformer).Ifs indicated that the oil level is within the normal range.1.2.4 Oil Tank of the Transformer and Other AccessoriesConservator Tank(Oil Conservator)1.2.4 Oil Tank of the Transformer and Other Accessories0Oil conservator with a sealed rubber air bag and a dial1.2.4 Oil Tank of the Transformer and Other Accessories1 IBreather(The desiccant air dryer which is filled with silica gel)FunctiorInspect1ObservePreventing water in air from entering the transformer.Silica gel is blue when ifs dry.It turns pink after saturation by moisture absorption.1.2.4 Oil Tank of the Transformer and Other Accessories1.2.4 Oil Tank of the Transformer and Other AccessoriesCoolerDecrease the temperatures of iron core and windings by decreasing the temperature of the transformer oil.7unctio:Oil-immersed self cooling,oil-immersed air cooling,forced oil circulation air cooling.The fan and oil pump are in normal operation.1.2.4 Oil Tank of the Transformer and Other Accessories01.2.4 Oil Tank of the Transformer and Other Accessories1.2.4 Oil Tank of the Transformer and Other AccessoriesInsulating BushFix the outgoing line of the winding,and insulate the outgoing line and the oil tank.7unctio:Ceramic oil-filled bushing or condenser bushing.Whether there is any crack on the bushing,whether there is partial discharge and whether the outgoing line is overheated.1.2.4 Oil Tank of the Transformer and Other Accessories1.2.4 Oil Tank of the Transformer and Other Accessories0Tap Changer7unctio:Regulate the voltage by changing the number of connected turns of the high-voltage winding.For example,5%,2x2.5%tap.鼠 FormOff-circuit tap changing transformer(must be operated when the transformer is power-off)FormUnder-load tap changer transformer(be able to be operated when with load)1.2.4 Oil Tank of the Transformer and Other Accessories1.2.4 Oil Tank of the Transformer and Other Accessories1.2.4 Oil Tank of the Transformer and Other Accessories0Pressure Relief ValveTo prevent explosion of the transformer when a serious accident happens,the distribution transformer adopts the vent pipe for protection.1.2.4 Oil Tank of the Transformer and Other Accessories0Gas Relay(Buchholz Relay)FunctionProtective!Action j k Mode，A type of protector which will be forced to react by the gas and oil flow produced when some malfunction takes place(such as insulation breakdown,turn-to-turn short circuit,iron core accident,decline of oil level due to oil leak from the oil tank etc).When the malfunction is light,it only give out acoustic and optical signals,so that the operator can deal with it in time.If the malfunction is serious,the relay will trip out,so that the transformer is protected.1.2.4 Oil Tank of the Transformer and Other AccessoriesQ