Radiated electromagnetic field (EMI) in space is mainly generated by power network, transient process of electrical equipment, lightning, radio broadcasting, television, radar, high-frequency induction heating equipment, etc. It is usually called radiation interference, and its distribution is extremely complex. If the PLC system is placed in the radio frequency field, the radiation interference will be recovered, and its influence will mainly pass through two paths: one is the direct radiation inside the PLC, which is caused by circuit induction; the other is the radiation to the PLC communication network, which is caused by Induction of communication lines introduces interference. Radiated interference is related to the layout of the field equipment and the size of the electromagnetic field generated by the equipment, especially the frequency, and is generally protected by setting up shielded cables and PLC partial shielding and high-voltage relief components.
Interference from the external leads of the system
Mainly introduced through power and signal lines, usually called conducted interference. This kind of interference is more serious in my country’s industrial scene.
Interference from the power supply
Practice has proved that there are many cases of PLC control system failure caused by the interference introduced by the power supply. The author encountered it during the debugging of a project, and the problem was solved by replacing the PLC power supply with higher isolation performance.
The normal power supply of the PLC system is powered by the grid. Due to the wide coverage of the grid, it will be subject to all space electromagnetic interference that induces voltages and circuits on the line. In particular, the changes in the power grid, such as the operation surge of the incoming switch, the start and stop of large power equipment, the harmonics caused by the AC and DC transmission devices, and the short-circuit transient impact of the power grid, etc., are all transmitted to the primary side of the power supply through the transmission line. PLC power supply usually adopts isolated power supply, but its mechanism and manufacturing process factors make its isolation not ideal. In fact, due to the existence of distributed parameters, especially distributed capacitance, absolute isolation is impossible.
Antec / Lightwave Communications LLMM Chassis VME
CTI Cryogenics 8510 Water Cooled Compressor PN: 8031315
Eventide VR320 Digital Audio Communications Logger
GCA David W. Mann Pattern Generator 3000
Markem 200-AH Horizontal Marking Machine
Markem 200-AD Vertical Down Flat Surface Marking Machin
Hepco 5000-40 Lead Former W/ VFC Parts Feeder
Ascension Spect-A-Lift Vertical Scissor Lift 41”H Moves
Motorola XR867KC-V3 MVME Drive Module DRMOD
Haskris R100-BCS Water Cooled Recirculating Chiller
DIP-Proofing DPI0.5K23A5/6-P w/ DPI0K523A6-I Inverter
SPECTRA-PHYSICS 125A LASER HEAD & 261 EXCITER
Burton Style 12114 Filament / Welding Transformer 8kVA
Data I/O ProMaster 2500 Handler / Programmer / Labeler
Beckman L5-50 Ultra Centrifuge w/ W2T Integrator T42.48
Amsco M71GA Gas Aerator Last Gas Used: Amprolene
Panasonic Color Video Camera WV-F70 w/ WV-RC36 Control
DVT 630 SmartImage Sensor Machine Vision Camera, Lens +
Saint-Gobain AstiPure PFD3 322S Controlled Flow Pump
Savant HSC-10K-AC High Speed Benchtop Centrifuge
MSA Ultralite II Self-Contained Breathing Apparatus
Fujitsu FC9607HTL1 Wideband Unit for FLM 2400 ADM
Met One 237B Airborne Particle Counter 237B-.3-.1-1 NEW
Met One 237B Airborne Particle Counter 4-CH
Wafab WHRV-1212-134A Temperature Controlled Circulator
Bold Technologies Auto Heater/Chiller Module 940-2201
Wescor 5130 Vapor Pressure Osmometer Biomedical Use
L-3 Communications DSM720-PCI DSM720-PC Decom/Simulator
Motorola MVME328-1 MVME 328-1 SCSI VME Board
Beckman JA-20 Rotor, Fixed Angle, 8 x 50mL, 20,000RPM
Fuji FujiFilm MiniLab FP362BAL Optical Film Processo
