12kV中置式开关柜中2500A电流互感器温升分析及对策

Temperature Control Analysis and Countermeasure of 12kV Indoor Metal-clad Switchgear with 2500A Current Transformer

负荷电流、环境温度、导体电阻与接触电阻决定开关柜温升,大电流互感器温升对开关柜影响至关重要。其热源主要由导体电阻、接触电阻、铁芯涡流损耗和二次绕组电阻产生。环氧树脂包封块状式电流互感器内部热源和外部热源形成了内外持续的温度场。适当增加导体截面,改善搭接块连接方式,改进内部导体结构,可达到限制热源的目的。电缆室门进风口和出风口由原来的不锈钢纱网更换为黑色的释压板,增强了散热效果。型式试验表明,2500 A电流互感器的新设计、新工艺能够满足中置式开关柜国家标准温升要求。

The temperature of the indoor metal-clad switchgear depend on the load current,ambient temperature,conductor resistance and contact resistance.Furthermore,it is very important of the heat from the large current transformer.The heat producer is main from its conductor resistance,contact resistance,Iron core vortex and secondary winding resistance.The epoxy resin of block-type current transformer envelope its inner heat and outside heat that the internal and external continuous temperature field is formed.To increase the conductor cross-section appropriately and improving the lap-up block connection mode and its the internal conductor structure may achieve the fundamental purpose of limiting the heat source.And in order to enhance the heat dissipation effect,the stainless steel yarn mesh derived from the air inlet and air outlet of the cable chamber door is replaced with a black pressure release plate.Type test shows,that the new design and new process of 2500 A current transformer and improvement of air inlet and air outlet materials can meet the temperature requirements of the national grid standard of indoor Metalclad Switchgear.