51304485-150

3.PLC控制系统中电磁干扰的主要来源有哪些呢？

  (1)来自空间的辐射干扰

  空间的辐射电磁场（EMI）主要是由电力网络、电气设备的暂态过程、雷电、无线电广播、电视、雷达、高频感应加热设备等产生的，通常称为辐射干扰，其分布极为复杂。若PLC系统置于所射频场内，就回收到辐射干扰，其影响主要通过两条路径；一是直接对PLC内部的辐射，由电路感应产生干扰；而是对PLC通信内网络的辐射，由通信线路的感应引入干扰。辐射干扰与现场设备布置及设备所产生的电磁场大小，特别是频率有关，一般通过设置屏蔽电缆和PLC局部屏蔽及高压泄放元件进行保护。

  (2)来自系统外引线的干扰

  主要通过电源和信号线引入，通常称为传导干扰。这种干扰在我国工业现场较严重。

  (3)来自电源的干扰

  实践证明，因电源引入的干扰造成PLC控制系统故障的情况很多，笔者在某工程调试中遇到过，后更换隔离性能更高的PLC电源，问题才得到解决。

  PLC系统的正常供电电源均由电网供电。由于电网覆盖范围广，将受到所有空间电磁干扰而在线路上感应电压和电路。尤其是电网内部的变化，入开关操作浪涌、大型电力设备起停、交直流转动装置引起的谐波、电网短路暂态冲击等，都通过输电线路到电源边。PLC电源通常采用隔离电源，但其机构及制造工艺因素使其隔离性并不理想。实际上，由于分布参数特别是分布电容的存在，隔离是不可能的。

  (4)来自信号线引入的干扰

  与PLC控制系统连接的各类信号传输线，除了传输有效的各类信号之外，总会有外部干扰信号侵入。此干扰主要有两种途径：一是通过变送器或共用信号仪表的供电电源串入的电网干扰，这往往被忽略；二是信号线受空间电磁辐射感应的干扰，即信号线上的外部感应干扰，这是很严重的。由信号引入干扰会引起I/O信号工作异常和测量精度大大降低，严重时将引起元器件损伤。对于隔离性能差的系统，还将导致信号间互相干扰，引起共地系统总线回流，造成逻辑数据变化、误动和死机。PLC控制系统因信号引入干扰造成I/O模件损坏数相当严重，由此引起系统故障的情况也很多。

Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS New Fanuc A06B-6240-H308 Servo Amplifier Fast ship with warranty
Brand New
   36  346  58
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS New SIEMENS 7ML5431-0AD00-1DC1 Fast ship with warranty
Brand New
   36  279  16
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW MITSUBISHI MR-J3-500B4 Fast Ship
Brand New
   36  266  72
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW FANUC A06B-0238-B805 Fast ship with warranty
Brand New
   36  242  33
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS New Sick S30A-7011CA Safety Laser Scanner Fast Ship
Brand New
   36  173  53
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand New MOXA ThinkCore V481-CE Fast Ship
Brand New
   36  139  47
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW Mitsubishi HF303S-A48 Fast Ship
Brand New
   36  139  33
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW panasonic 15KW MDMEC52G1G Fast Ship
Brand New
   36  139  33
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW EMERSON EV2100-4T1100A Fast Ship
Brand New
   36  139  33
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW Mitsubishi FR-F840-01160-2-60 (55KW Fast Ship
Brand New
   36  139  33
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW IN BOX Yaskawa SGM7G-1EAFC6C Fast Ship
Brand New
   36  117  23
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand NEW Mitsubishi FR-A720-37K 200V Fast Ship
Brand New
   36  090  33
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW NORGREN VP2310BD461MB200 Fast Ship
Brand New
   36  063  02
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW LS SV370IS5-4 Fast Ship
Brand New
   36  063  02
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW Yaskawa SGDV-590A11A Fast Ship
Brand New
   36  063  02
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW Mitsubishi MDS-D-SP-640 Fast Ship
Brand New
   36  062  88
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW E+L FR5503 Fast Ship
Brand New
   36  062  88
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand NEW MOXA EDS-408-SS-SC-T Fast Ship
Brand New
   36  062  81
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand NEW MOXA EDS-308-SS-SC-80-T Fast Ship
Brand New
   36  062  81
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand NEW MOXA EDS-308-S-SC-80-T Fast Ship
Brand New
   36  062  81
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    FUJI G11 FRN132G11S-4CX 132KW Fast Ship
Pre-Owned
   36  062  26
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand New Danfoss vlt2881pt4b20sbr0dbf12a00c1134h2470 Fast Ship
Brand New
   36  056  07
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    FANUC A06B-2257-B400 Tested in Good condition
Pre-Owned
   36  026  88
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW YASKAWA CIMR-LB4A0112 Fast ship with warranty
Brand New
   36  026  88
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS New Fanuc A06B-6121-H030#H550 Servo Amplifier Fast Ship
Brand New
   36  014  23
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand New Siemens M440 6SE6440-2UE31-8DA1 Fast ship with warranty
Brand New
   35  992  13
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    Fanuc A06B-6127-H109 Servo Amplifier In Good Condition
Pre-Owned
   35  974  76
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand New Siemens M440 6SE6440-2UE31-5DA1 Fast ship with warranty
Brand New
   35  971  98
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand NEW IN BOX FANUC A06B-2227-B300 Fast ship with warranty
Brand New
   35  929  58
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW IN BOX SIEMENS PLC 6SN1118-0DG21-0AA1 Fast ship with warranty
Brand New
   35  906  65
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    FANUC A06B-0288-B010 Tested in Good condition
Pre-Owned
   35  873  98
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW Yaskawa SGDH-15DEY359 Fast Ship
Brand New
   35  836  45
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW Yaskawa Servo Motor SGMGH-1EACA61 Fast Ship
Brand New
   35  823  25
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS New In Box ABB PFEA112-20 3BSE050091R20
Brand New
   35  812  48
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW MDS-CH-CV-220 MDSCHCV220 MITSUBISHI POWER SUPPLY UNIT
Brand New
   35  778  08
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS New Siemens 6RA8075-6DV62-0AA0 Fast ship with warranty
Brand New
   35  687  03
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand New SIEMENS 7ML5431-0AD00-1DC0 Fast ship with warranty
Brand New
   35  641  86
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    Cisco AS5350XM Tested in Good condition
Pre-Owned
   35  589  73
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand New Siemens M440 6SE6440-2UD34-5FB1 Fast ship with warranty
Brand New
   35  588  34
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW YASKAWA SGMGH-44ACA61+SGDM-50ADA Fast Ship
Brand New
   35  573  75
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    FANUC A06B-6164-H311#H580 Tested In Good Condition Fast Ship
Pre-Owned
   35  520  72
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS New Siemens 6ES7 416-3XL04-0AB0 6ES7416-3XL04-0AB0 In Box
Brand New
   35  485  49
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW IN BOX FUJI Inverter FRN55G1S-4C Fast Ship
Brand New
   35  458  66
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand NEW IN BOX FANUC A02B-0309-B520 Fast ship with warranty
Brand New
   35  448  65
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    KEYENCE CV-5701CA-DC21E Tested in Good Condition Fast Ship
Pre-Owned
   35  443  51
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS Brand NEW Yaskawa servo motor SGMGV-1EADA61 Fast Ship
Brand New
   35  413  21
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS    FUNAC A02B-0280-B502 A02B0280B502 OI/MA system Tested
Pre-Owned
   35  412  51
  
Free Shipping
 Watch
From Hong Kong
Get fast shipping and excellent service when you buy from    Top-rated sellers
Item image
1PCS NEW Mitsubishi servo drive MDS-C1-SP-300 MDSC1SP300 Fast Ship
Brand New
   35  395  69