SGM-08A3B4PL
3.PLC控制系統(tǒng)中電磁干擾的主要來源有哪些呢？
(1)來自空間的輻射干擾
空間的輻射電磁場（EMI）主要是由電力網(wǎng)絡、電氣設備的暫態(tài)過程、雷電、無線電廣播、電視、雷達、高頻感應加熱設備等產(chǎn)生的，通常稱為輻射干擾，其分布極為復雜。若PLC系統(tǒng)置于所射頻場內，就回收到輻射干擾，其影響主要通過兩條路徑；一是直接對PLC內部的輻射，由電路感應產(chǎn)生干擾；而是對PLC通信內網(wǎng)絡的輻射，由通信線路的感應引入干擾。輻射干擾與現(xiàn)場設備布置及設備所產(chǎn)生的電磁場大小，特別是頻率有關，一般通過設置屏蔽電纜和PLC局部屏蔽及高壓泄放元件進行保護。
(2)來自系統(tǒng)外引線的干擾
主要通過電源和信號線引入，通常稱為傳導干擾。這種干擾在我國工業(yè)現(xiàn)場較嚴重。
(3)來自電源的干擾
實踐證明，因電源引入的干擾造成PLC控制系統(tǒng)故障的情況很多，筆者在某工程調試中遇到過，后更換隔離性能更高的PLC電源，問題才得到解決。
PLC系統(tǒng)的正常供電電源均由電網(wǎng)供電。由于電網(wǎng)覆蓋范圍廣，將受到所有空間電磁干擾而在線路上感應電壓和電路。尤其是電網(wǎng)內部的變化，入開關操作浪涌、大型電力設備起停、交直流轉動裝置引起的諧波、電網(wǎng)短路暫態(tài)沖擊等，都通過輸電線路到電源邊。PLC電源通常采用隔離電源，但其機構及制造工藝因素使其隔離性并不理想。實際上，由于分布參數(shù)特別是分布電容的存在，隔離是不可能的。
(4)來自信號線引入的干擾
與PLC控制系統(tǒng)連接的各類信號傳輸線，除了傳輸有效的各類信號之外，總會有外部干擾信號侵入。此干擾主要有兩種途徑：一是通過變送器或共用信號儀表的供電電源串入的電網(wǎng)干擾，這往往被忽略；二是信號線受空間電磁輻射感應的干擾，即信號線上的外部感應干擾，這是很嚴重的。由信號引入干擾會引起I/O信號工作異常和測量精度大大降低，嚴重時將引起元器件損傷。對于隔離性能差的系統(tǒng)，還將導致信號間互相干擾，引起共地系統(tǒng)總線回流，造成邏輯數(shù)據(jù)變化、誤動和死機。PLC控制系統(tǒng)因信號引入干擾造成I/O模件損壞數(shù)相當嚴重，由此引起系統(tǒng)故障的情況也很多。
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
TEWS Technologies TVME200-10 VMEbus Carrier Board Rev A Ver 1 1
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Honeywell MU-TSTX03 Smart Transmitter Interface b 51309140-125 Rev B
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
TransData 8104-VD11 Analog Output Converter Module Ver 2 22
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Square D KHL36225 Circuit Breaker 225 Amps 600VAC 250VDC
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW ABB Kent-Taylor 326-LT Electronic Transmitter 275 PSIG 25 to 150 InH2O
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
GE Fanuc IC661EPM100J Genius PowerTRAC Electronic Module
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Mizar Inc VME 8610 Interface Control Board 8610-0-01 Rev D
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Matrox SX-900/64-8/B2 Graphics Imaging Card
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Honeywell 51402625-175 UCN Digital Input SOE Card HDW: H FW: G
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Taylor Instrument R1-176-LT Electronic Transmitter 146749-B
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Thermo Electron G4-SB500-N Load Cell 500 Pound Capacity
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Yokogawa EJA530A-EAS7N-02EE/FF1/D1 DP Harp Pressure Transmitter
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Honeywell 51304690-100 UCN Digital Input SOE Card HDW: H FW: F
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Honeywell 51304690-100 UCN Digital Input SOE Card HDW: J FW: F
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Bently Nevada 3500/92 Communication Gateway Module PWA 136180-01 Rev L
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Brooks Instrument MT3810 Armored Metal Tube Flow Meter 3810A14BAPAA1A1
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Unit / Celerity UFC-1665C Digital Metal Seal 1L H2 Multiflo SC15
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Danaher Dynapar M050786 Encoder 62-AADF-0900-AB
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Tucker B 346 E 110 344 Stud Welder Control Board
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Orbisphere Laboratories Model 2606 Oxygen Indicator 29034 2986
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
EHC 9607086 Mod 4 Control Board Assembly 9607087
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Fisher Rosemount KJ4001X1-BE1 Delta V 8 Wide Carrier Base Module Rev L
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Fisher Rosemount KJ4001X1-BE1 Delta V 8 Wide Carrier Base Module Rev J
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Bently Nevada 330705-02-18-10-02-00 3300 XL 11MM Proximity Probe
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Elliott P3850A060 Bearing Half Sleeve
Brand New
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Tucker B 346 A E 110 344 A Stud Welder Control Board
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Satec ETC2002 Inbligent Communication Device Network Communicator
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Fanuc A20B-1004-0850/05A Servo Amplifier Unit Control Board
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Emerson OCX 8800 Power Supply Assembly 6A00132G01 Rev 7
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
ABB DSQC 532A I/O Computer Board 3HAC18158-1
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Worthington 232100CJ1 Air Compressor Unloader Valve Assembly
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Honeywell MIDAS-T-001 Gas Analyzer Transmitter Assembly
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Telesis 23490-06 Marking System Controller Control Board Rev A
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Atlas Copco QCM-T 340 25 Servo Control Module 4240 0337 81 F/W 3 18 S/W 3 1
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Schrader Bellows M08444632 Manual Valve
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Industrial Devices Corporation IDC IM-LMT42 Impulse Microstepping Drive NC
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Brooks MT 3810 Armored Metal Tube Flow Meter 3810A14BAPAA1A1
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
General Electric 36B605218CA-A-X2 SV-1 Drive Module
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Kansai Automation Model KLI Capacitance Level Indicator Amplifier Unit
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Static Controls Corporation 1040-P-03-32-X Operator Interface Panel SCC
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
NEW Leeds & Northrup 075706 Preamplifier Module Rev B
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Fisher Rosemount CL6828X1-A1 Provox Smart Device Output 12P1395X032 Rev D
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
EST Model MVM Multiple Voice Message Module 240359 Rev D
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Carrier 32GA400504-2 Oil-Sense2 Oil Quality Alert Unit
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Allen Bradley 1756-L1/A ControlLogix Processor w/ 1756-M2/A Rev T01
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Allen Bradley 1756-L1/A ControlLogix Processor w/ 1756-M2/A Rev T01 B01
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Allen Bradley 1756-L1/A ControlLogix Processor w/ 1756-M2/A Rev R01
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Allen Bradley 1756-L1/A ControlLogix Processor w/ 1756-M2/A Rev S01 C01
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Foxboro B0133SH-D Memory Board F8620D L0118WF Rev A
Pre-Owned
2 606 21
Free Shipping
Watch
Get fast shipping and excellent service when you buy from Top-rated sellers
Item image
Toshiba VT130Q9U4110 Transistor Inverter Drive 11 kVA 10 HP 380-480V
Pre-Owned
2 606 21
