描述
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(chǎng)(EMI)主要是由電力網(wǎng)絡(luò)、電氣設(shè)備的暫態(tài)過程、雷電、無線電廣播、電視、雷達(dá)、高頻感應(yīng)加熱設(shè)備等產(chǎn)生的,通常稱為輻射干擾,其分布極為復(fù)雜。若PLC系統(tǒng)置于所射頻場(chǎng)內(nèi),就回收到輻射干擾,其影響主要通過兩條路徑;一是直接對(duì)PLC內(nèi)部的輻射,由電路感應(yīng)產(chǎn)生干擾;而是對(duì)PLC通信內(nèi)網(wǎng)絡(luò)的輻射,由通信線路的感應(yīng)引入干擾。輻射干擾與現(xiàn)場(chǎng)設(shè)備布置及設(shè)備所產(chǎn)生的電磁場(chǎng)大小,特別是頻率有關(guān),一般通過設(shè)置屏蔽電纜和PLC局部屏蔽及高壓泄放元件進(jìn)行保護(hù)。
(2)來自系統(tǒng)外引線的干擾
主要通過電源和信號(hào)線引入,通常稱為傳導(dǎo)干擾。這種干擾在我國(guó)工業(yè)現(xiàn)場(chǎng)較嚴(yán)重。
(3)來自電源的干擾
實(shí)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(diào)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(yīng)電壓和電路。尤其是電網(wǎng)內(nèi)部的變化,入開關(guān)操作浪涌、大型電力設(shè)備起停、交直流轉(zhuǎn)動(dòng)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(jī)構(gòu)及制造工藝因素使其隔離性并不理想。實(shí)際上,由于分布參數(shù)特別是分布電容的存在,絕對(duì)隔離是不可能的。
(4)來自信號(hào)線引入的干擾
與PLC控制系統(tǒng)連接的各類信號(hào)傳輸線,除了傳輸有效的各類信號(hào)之外,總會(huì)有外部干擾信號(hào)侵入。此干擾主要有兩種途徑:一是通過變送器或共用信號(hào)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(hào)線受空間電磁輻射感應(yīng)的干擾,即信號(hào)線上的外部感應(yīng)干擾,這是很嚴(yán)重的。由信號(hào)引入干擾會(huì)引起I/O信號(hào)工作異常和測(cè)量精度大大降低,嚴(yán)重時(shí)將引起元器件損傷。對(duì)于隔離性能差的系統(tǒng),還將導(dǎo)致信號(hào)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(dòng)和死機(jī)。PLC控制系統(tǒng)因信號(hào)引入干擾造成I/O模件損壞數(shù)相當(dāng)嚴(yán)重,由此引起系統(tǒng)故障的情況也很多。
歐美品牌停產(chǎn)的,常用的“PLC”備品備件
我司產(chǎn)品應(yīng)用于以下領(lǐng)域:
1,《發(fā)電廠DCS監(jiān)控系統(tǒng)》
2,《智能平鋼化爐系統(tǒng)制造》
3,《PLC可編程輸送控制系統(tǒng)》
4,《DCS集散控制系統(tǒng)》
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5,《智能型消防供水控制系統(tǒng)》
6,《化工廠藥液恒流量計(jì)算機(jī)控制系統(tǒng)》
7,《電氣控制系統(tǒng)》造紙,印染生產(chǎn)線,變電站綜合自動(dòng)化控制系列
本特利,英維思,伍德沃德,??怂共_、西屋、瑞恩、施耐德莫迪康、ABB、AB、西門子、摩托羅拉、GE發(fā)那科、安川、博世力士樂,ACSO,力士樂等各大品牌的DCS系統(tǒng)配件,機(jī)器人系統(tǒng)配件,大型伺服系統(tǒng)備件。
SMC SOLENOID SY3120-6LZD-C4(LOT OF 3)
NEMA 34 Planetary Gearhead 518-43-010 Minarik Drives
Panasonic Servo Drive&Motor Set MUDS041A1A
Agilent HP 84000-60189 3.5mm Test Port Cable
SEALEVEL PCI RS-232 RS-422 RS-485 Interface 7202 rev C
OMRON VISION MATE CONTROLLER F350 F350-C10 F300-A20
Olympus WHSZ10X-H/22 Eyepieces
GE Fanuc S2K Servo Drive&MTR-3N31 Servo Motor Set
Interface PCI expansion interface module PCI-2724C 2724
PANTHER H12 Intelligent Motion System IMS
Agilent 11683A RANGE CALIBRATOR WITH OPTION H01
Delta Tau Data Systems PMAC-PC 602705-107 CPU+ram
NAIS M1T MICRO CONTROL UNIT PLC
Soder-Wick 50-4 25ft SIZE#4 QTY=5
Delta Tau Data Systems PMAC Lite 602402-105 602192-103
Delta Tau Data Systems Universal PMAC Lite 602402-105
Coherent FieldMaster Field Master Power Energy Meter
OMEGA DP25-S STRAIN GAUGE METER
FOculus FO442SB IEEE 1394 Digital CCD Firewire Camera
OPTEM 18-108 f/2.5 close 34-11-10 MACRO VIDEO ZOOM LENS
IDEC POWER SUPPLY PS5R-D24 PS5RD24 24VDC 2.1A Qty:3
OPTO 22 SNAP-PS5-24DC SNAP-PS5 SNAP I/O 5V 4Amp QTY:2
QUANTRONIX QS27-4SN-QX1 LIGHTWRITER SPE Q-SWITCH
National Instruments NI PXI-6031E DAQ Board
Agilent 08485-60005 3.5mm(f)-N(m)Adapter 50 MHz
MATROX Meteor II Multi-Channel METEOR2-MC/4
Agilent HP 8765B Coaxial Switch DC-20GHz with Opt 024
Agilent HP 87300C Coaxial Directional Coupler 1-26.5GHz
HP NC364T Quad Port Gigabit Server Adapter 436431-001
PIXERA 001226-001 Rev F PCI CARD
MATROX Meteor II Multi-Channel METEOR2-MC/4
MATROX Meteor II Multi-Channel METEOR2-MC/4/16?F
PARKER COMPUMOTOR SX8 MICROSTEP DRIVE/INDEXER
MATROX METEOR2 CL/32 METEOR Camera Link Frame Grabber
TOTAL CONTROL QPI21100E2P QUICKPANEL 9″TOUCHSCREEN
Magnum ISA Bench Card 000-878004 050-878004 000-868704
Dell Latitude D410 Motherboard&1.6Ghz CPU G8336
Lot of 2 Gore ReadyFlex Microwave Cable Assemblie 18GHz
HUBER-SUHNER SUCOFLEX 104A 8120-4921 Cable 26.5GHz NEW
EDC BIOSYSTEMS LIQUID HANDLING PROCESS CONTROLLER PANEL
TRILLIUM HAND HELD CONTROLLER OT-30 PART#874-5242-01
HP Agilent 1NB7-8539
Agilent HP 08487-60001 2.4mm(f)-N(m)Adapter 50MHz
Agilent 5065-7021
Agilent HP E3614A 0-8VDC 6A DC Power Supply
Agilent 5065-6980
Agilent HP 10498-60001 10498A 8 CH Probe Lead Set
Lot of 3 TAKEX Fiber Optic Sensor FR2-Slim Type
KDI 64537 PQ-1846 Microwave RF Directional Coupler
HP Agilent 1NB7-8539
MITSUBISHI A1SJ71UC24-R2 RS-232-C UNIT NEW
MITSUBISHI A1SY41 OUTPUT MODULE NEW
YAMATAKE HONEYWELL MX100PT12 32PT TRANSISTOR OUT
Allen Bradley 1762-IQ8 MicroLogix DC Input Module QTY=2
Mitsubishi FX2N-80MR-ES/UL FX2N80MRESUL PLC
HITACHI KP-D50 DIGITAL COLOR CAMERA
JVC.TK-C1481BEG?.LO-LUX CCTV COLOUR CAMERA
AVME-311AF AVME 311AF FUJI K2056D
Yamatake Honeywell MX250RV01 VME Interface Board
Texas Instruments 435 Complete PLC
Keyence LS-3101 Laser Scan Micrometer+Scanning Heads
COGNEX VISION SYTEM IN-SIGHT-3400 CAMERA MODULE
FUJI FH1016A VM1440A SIX CHANNEL COMMUNICATION BOARD
FUJI AVAL VME-520 MCIF-16 BOARD CARD
HITACHI ZOSEN HIMV-923A/924A HIMV-924A2 WITH 2M FLASH
Adept Technology 10332-12410 MI-6 VME BOARD STAUBLI
RKC FAREX SRM SR Mini HG SYSTEM
WYKO PCB 619-152 PCI Card
COGNEX 4400 VM13B REV T VISION PROCESSOR MODULE
GE FANUC 90-30 PLC 5 SLOT SYSTEM Stepper Motor
Agilent 20mm Torque Wrench 8710-1764
COGNEX CHECKER 101 807-0007-2 REV A VISION CAMERA
Lot of 2 CrystalFontz 634 CFA-634 LCD Dispaly
National Instruments NI GPIB PCIe PCIe-GPIB
AMD Turion 64 X 2 TL52 1,6 Ghz TMDTL52HAXSCT
Micro-Coax 26GHZ 84 inch Flexible Microwave Cable
NARDA POWER DIVIDER 4456-2 FROM 2.0 to 18 GHz
STORM TRUE BLUE 205 18GHZ 72 inch Flexible CABLE
Galil Motion Controls DB 1004 DAUGHTER BOARD Rev-C
Galil 6-AXIS Motion Controller DMC-1060 DMC1060 Rev G
BERKELEY PROCESS CONTROL BX I/O WITH INPUT&OUTPUT
Agilent 1250-1529 Adapter Type-N(f)to Type-N(f)75
KEYENCE KV-24DR PLC with KV-U2 POWER SUPPLY
Agilent 1250-1476 Adapter Type-N(m)to BNC(f)NEW
HP 44727A 4 Ch Voltage/Current DAC
HP 44705A 20 CHANNEL RELAY MULTIPLEXER
Sorensen DCS80-13E DC Programmable Power Supply
SUNX S link SL-T8J,SL-T16C1 and SL-TP16C1
CORECO PC-CAMLINK PCI UNIQ UP-2000CL CCD DIGITAL CAMERA
JSR Ultrasonics RP-U2 SONIX ECHO remote pulser
NAVITAR 6000 60095 Lens 1-60095 High Mag Zoom
LiNOS 4401-256-000-20 1064nm 2-8X Laser Beam Expander
QUANTRONIX LASER HEAD PUMP CHAMBER
QUANTRONIX 0201-03199 Cavity Assembly
QUANTRONIX SHUTTER Assembly 319 0103-00483 REV G NEW
Cognex In-Sight 5400 Smart Cameras With Cable
Vision Control PSO 90-100/125 deflectors 90 degrees