【2017年整理】电磁兼容培训胶片(地线干扰与对策).ppt

第二章 地线干扰与接地技术 为什么要地线 地环路问题与解决方法 公共阻抗耦合问题与解决方法 各种接地方法 电缆屏蔽层的接地 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 安全地 220V 0V + + + + + Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 信号地 定义：信号电流流回信号源的低阻抗路径 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 地线引发干扰问题的原因 V = I R 地线电压 地线是等电位的假设不成立 电流走最小阻抗路径 我们并不知道地电流的确切路径 地电流失去控制 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 地线电位示意图  2mV 200mV 2mV ~ 10mV 10mV ~ 20mV 20mV ~ 100mV 100mV ~ 200mV Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 导线的阻抗 Z = RAC + jL L  1H/m   = 1 / ( f r r)1/2 RAC= 0.076r f1/2 RDC r 电流 深度 0.37I I 趋肤效应 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 导线的阻抗 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 金属条与导线的阻抗比较 0 0.1 0.2 0.3 0.4 0.5 0.6 1 2 3 4 5 6 7 8 9 10 S / W 金属条阻抗/导线阻抗 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 地线问题－地环路 IG VG VN 地环路 I1 I2 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 隔离变压器 屏蔽层只能接2点！ C2 VG 1 2 C1 屏蔽 CP VG VS VN RL Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 光隔离器 发送 发送 接收 接收 RL RL VG VS VS VG 光耦器件 Cp Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 共模扼流圈的作用 Vs R1 R1 RL L VG IN1 IN2 IS VS + VN  = R1 / L VN / VG RL/（RS + RL） M f Evaluation only. Created with Aspose.Slides for .NE