.61Ir(KA)40I//(KA)22.61Ir(KA)31.5ich(KA)57.66idw(KA)100ich(KA)57.66idw(KA)80I2∞tdz22.612X0.75Ir2t402×4I2∞tdz22.612×0.75Ir2t31.52×4隔离开关选择结果如下:10KV主变侧隔离开关选GN2-10型,负荷侧选GN8-10型2、校验:(1)35KV侧隔离开关选GW28—35型Ie=600AIgmax=496A所以Ie≥Igmax满足要求Ue=Ugmax=35KV所以Ue≥Ugmax满足要求a、热稳定校验:I2∞tdz≤I2rtI2∞tdz=8.2762×0.75=51.37(KA2·S)I2rt=6.62×5=217.8(KA2·S)I2∞tdz≤I2rt满足热稳定要求b、动稳定校验:ich≤idwich=21.2KAidw=50KAich<idw所以满足要求故所选GW28—35型隔离开关符合要求(3)10KV侧A、主变侧选IN28A—12/3150A型断路器Ie=3150AIgmax=1819A所以Ie≥Igmax满足要求Ue=12KVUgmax=10.5KV所以Ue≥Ugmax满足要求a、热稳定校验:I2∞tdz≤I2rt即:tjs=tb+td=0.5+0.5=1s(不考虑非周期分量)在β//=1时,查《发电厂电气设备》中周期分量等值时间曲线,得tdz=0.75s所以I2∞tdz=22.612×0.75=383.41(KA2·S)I2rt=402×4=6400(KA2·S)I2∞tdz≤I2rt满足热稳定要求b、动稳定校验:ich≤idwich=57.66KAidw=100KAich<idw所以满足要求c、开断电流校验:Iekd>I//Iekd=40KAI//=22.61KAIekd>I//所以满足要求故所选ZN28A—12/3150A型断路器符合要求
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