EMC Shielding is a method used to protect a sensitive signal or electronics from external electromagnetic; it also prevents the strong signal from leakage and interference. Electromagnetic interference generally occurs when electromagnetic energy from an external source affects an electrical system.
EMI is encountered by all of us in our daily life with the growing use of wireless devices, cell phones, GPS, Bluetooth, WI-Fi, etc. the density of the electromagnetic in the environment continues to increase, and concern about its effects also increases.
Ambient EME includes
- Some of the sources of EMI are listed below.
- analog and digital Television transmissions
- Solar Magnetic Storms
- Lightning which occurs high voltage and current event
- Utility power grid transmission line
- Other EMI source include earth’s magnetic field flux, Broadband, airport port radar, electrostatic discharge (ESD), white noise, switching mode power supplies, motor bushes, etc
High Powered Electromagnetic Pulse devices facilitate many sources which includes
- IEMI source (Intentional Electromagnetic Interference)
- HNEMP (High Altitude Nuclear Electromagnetic Pulse)
- HPM (High Powered Microwave Weapon)
- EMP Cannon
- military tactical weapon
- Power Quality degradation factors include
- Voltage surges, spikes
- high and low voltage
- Brownouts and blackouts
- Faults in power
- EFT (Electrical Fast Transitions)
- Electrical noise on the mains power line
Mass Transit Systems and Railroad source includes –
- high voltage in Propulsion system’s
- high current operational mode emissions
- rail shoes arcing broadband
- high voltage contact switching
- Train control system emission
- Track control circuits
Medical equipment source includes
- Life support equipment such as infusion pump, cardiac defibrillators, ventilators, etc
- Patient telemetry assistance equipment e.g. electrocardiographs
- Electrical surgical unit
- MRIs (Magnetic Resonance Imaging system)
- Gamma Beam Electron Accelerators
- X-ray units
- Therapeutic equipment
SOURCES AND THEIR MOST SIGNIFICANT EFFECTS
- Ambient EME is composed of numerous sources that can affect sensitive electronic equipment of the EMI source. The closer the EMI equipment, the higher will be radiated power level. In-band frequency, EMI will cause interference problems. It can also cause upset, burn out, and latch-up in these units.
- HEMP can totally destroy electronic equipment function. These sources are specially designed to be utilized by military and terrorist. eg HNEMP device can totally immobilize the whole of the continental infrastructure. IEMI, Bombs are used to disable specific locations systems.
- High Powered Electromagnetic Pulse devices are capable of destroying interface electronic circuits. They can also affect the normal operation of the equipment.
- Power Quality distortions that are present in the main system can affect the normal operation of the equipment. Surges are able to destroy interface electronic circuits.
- Mass Transit Systems and Railroad operates with high voltages, currents, and magnetic field levels and can affect sensitive electrical equipment that is located near them.
- Medical equipment which includes monitoring systems is very susceptible to EMI. They monitor very weak human body signals and are measured in units of micro amps and micro volts.