EMC EQUIPMENT


OF.EMC-1



         
Conducted Emissions

Electrical and electronic devices are sources of unwanted electromagnetic energy. A certain portion of this energy propagates through the different types of cables to which the devices are connected, in particular through the power cables used to supply power to the devices themselves.
Unwanted currents propagating through a power supply cable can also be injected into the electrical power distribution network, thereby increasing the range of the disturbance effect. The unwanted signals emitted by a system that propagate to other systems through the various types of cables are called Conducted Emissions.
In order to limit the effects of interference generated at each level by the Conducted Emissions, these emissions are measured in the laboratory and verified that they comply with the limits specified by the Standards. From the point of view of laboratory tests, Emissions Conduits are all radio frequency emissions, included in the 150 KHz / 30 MHz band, generated and transmitted through the power cable in the environment surrounding the Electrical and / or electronic Device in test (DUT: Device Under Test).
The OF.EMC-1 Conducted Emissions measuring system, specially designed to meet the requirements of the standards, consists of the following units:

- EMC-0110: Single-phase isolation transformer 3500 VA  EMC-0120: Single-phase LISN network 16 A 150 KHZ / 30MHZ
- EMC-0130: 3/6/10/20 dB attenuator set
- EMC-0140: RF limiter
- EMC-0150: 150KHz-30MHz RF Preselector
- EMC-0160: 150KHz-30MHz RF Preamplifier
- EMC-0170: Measurement site for conducted emissions
- EMC-0180: Set of RF and power cables.
- EMC-0190: Series of technical and educational manuals related to the equipment used

OF.EMC-2



         
Irradiate Emissions

The irradiated emissions are represented by electromagnetic energy that propagates through the space. Sources of irradiated electromagnetic emissions are:
- connection cables (both power and signal) of electrical and electronic devices: the cables act as true RF antennas;
- the metal containers in which the devices are enclosed: on the metal containers (conductors) induced currents are generated which can radiate both in the internal and in the external environment;
- In low-cost systems, plastic containers ensure that the internal circuits are completely exposed to electromagnetic emissions, which means they can radiate directly and be subject to external interference.
The evaluation of the Irradiated Emissions taken into consideration by the EN standards for commercial and industrial equipment concentrates on the Emissions in the frequency range from 30MHz to 1GHz.
In some cases it may be necessary to carry out measurements above 1GHz (example: on some types of radiofrequency (RF) equipment to which EN 55011 - CISPR11 standards apply) or in other cases it may be necessary to perform measurements below 30MHz (example: on cable distribution systems).
The military radiated emissions test covers a much wider range of 30MHz ÷ 1GHz.
The EMC-2 Radiated Emission measuring system, specially designed to meet the requirements of the standards, operates in the 30 MHz ÷ 1 GHz range, and consists of the following units:
- EMC-0210: 30MHz / 1000 MHZ periodic Bilog antenna  EMC-0220: table-top EMI antenna
- EMC-0230: 3/6/10/20 dB attenuator set
- EMC-0240: 30MHz / 1000MHZ RF Preamplifier
- EMC-0250: RF 30MHz / 1000 MHZ preselector
- EMC-0260: Set of RF and power cables.
- EMC-0270: Series of technical and educational manuals related to the equipment used

OF.EMC-3



         





RF Conducted Immunity

The Electromagnetic Compatibility analyzes prescribed by the standards foresee the EMC Immunity tests, that is the measurement of the sensitivity (susceptibility) of the Device under examination (DUT) to suffer interference from equipment operating in the same environment.
A specific type of measurement is that which evaluates the immunity of the DUT to the interferences that can be channeled (conducted) through the connection cables (both power supply and signal cables) to which the Device is connected.
This particular type of examination is called Radio Frequency Conducted Immunity (in short Immunity Conduct). It should be remembered that, in most cases, interference from conducted RF signals is more efficient than that caused by the propagation in air.
The purpose of the test is the verification of the immunity of equipment, individual devices or systems to the perturbations induced by radio-frequency electromagnetic fields on: connection cables, power cables, signal lines and ground connection.
The test is carried out by placing the DUT on a table made of insulating material whose height, in relation to the ground plane, is indicated by the provisions of the applicable standard.
The DUT is connected via CDN (coupling / decoupling network) to the generator and to the amplifier. The EMC-03C Condensing Immunity measuring system, specially designed to meet the requirements of EN 61000-4-6 standards, operates in the 150 kHz to 80 MHz range, and is composed of the following units:
-EMC-03C10: RF generator - DDS 150 KHZ / 80 MHZ
-EMC-03C20: 150 KHZ / 80MHZ-10W wideband amplifier
-EMC-03C30: 6 dB power attenuator
-EMC-03C40: CDN set (5 types of common CDNs)
-EMC-03C50: Set of RF and power cables.
- EMC-03C60: Series of technical and educational manuals related to the equipment used.

OF.EMC-4



         
Irradiated RF Immunity

The Electromagnetic Compatibility analyzes prescribed by the standards foresee the EMC Immunity tests, that is the measurement of the sensitivity (susceptibility) of the Device under examination (DUT) to suffer interference from equipment operating in the same environment.
A specific type of measurement is that which evaluates the immunity of the DUT to the interference from electromagnetic fields irradiated in the air in an unwanted way by other electrical and electronic devices. The interfering EM fields they can be picked up either from the connection cables (power supply, signal cables, etc.) and directly from the device itself when it is not particularly protected against these types of interference.
This particular type of examination is defined as Radiation Frequency Radio Immunity (in short Radiated Immunity)
The purpose of the test is the verification of the immunity of equipment, single apparatuses or systems to the perturbations induced by irradiated radio-frequency electromagnetic fields.
The EN 61000-4-3 standard defines the place, the method, the levels and the test frequencies to which the D.U.T. Where it is not possible to generate RF fields of tens of volt / meter in open field (for fear of generating interference to external devices not connected to the test), said test should take place in the shielded room or, in the absence thereof, in appropriate TEM cells, after calibration of the system.
Ofel produces both a shielded room and a TEM cell appropriate to the standard. These can be supplied as optional items to the EMC-3 / I set.
The EMC-03 / I Radiated Immunity measuring system, specially designed to meet the requirements of the standards, operates in the 80 MHz ÷ 1 GHz range, and consists of the following units:
- EMC-03I10: 30MHz / 1GHz Periodic Bilog Antenna
- EMC-03I20: 9 KHz ÷ 1.5 GHz RF generator
- EMC-03I30: Wide Band Amplifier 80 MHz ÷ 1 GHz - 5 W
- EMC-03I40: Set of RF and power cables.
- EMC-03I50: Series of technical and educational manuals related to the equipment used.

OF.EMC-5



         

Measure of Harmonics & Flickers

The formal definition of "flicker" is the "impression of instability of the visual sensation induced by a light stimulus whose luminance or spectral distribution fluctuates over time".
The flicker can be considered as a symptom, deriving from the modulation of a load (the DUT) and the effects that this produces on its supply voltage. While the DUT is connected to a voltage source with a finite impedance, any modulation of the load will cause voltage fluctuations on the supply line.
The EN 61000-3-3 standard focuses mainly on the limitation of such fluctuations and consequent flicker on low-voltage public power systems. Voltage variations produced by electrical and electronic equipment when tested under the specified conditions must not exceed 4%.
The EMC-4 Harmonic Emissions and Flicker Measurement System, specially designed to meet the requirements of the standards, consists of the following units:
-EMC-0410: Network and Harmonic Analyzer
-EMC-0420: Low Distortion Power Supply for Network and Harmonic Analysis
-EMC-0430: Set of RF and power cables.
-EMC-0440: Series of technical and educational manuals related to the equipment used.

OF.EMC-6



         
Electrostatic Discharge Immunity

The standards used according to the type of equipment under test define the test level for that equipment and the type of electrostatic discharge.
The tests are carried out by means of an electrostatic discharge generator, generally supplied with tips for air discharge and contact discharge (sometimes called electrostatic "guns").
The discharges can be classified into two categories: direct and indirect. The first ones are those sent directly to the DUT (to simulate a discharge induced by any user) while the latter are sent to the DUT through a suitable vertical metal plane, to simulate a discharge induced by any nearby equipment.
According to the product to be tested, the standards define two types of tests: air discharge and contact discharge. With the first method the high voltage discharge takes place through the air dielectric. With the second method the operator injects the electrostatic disturbance directly on the product to be tested (discharge by direct contact) or on the vertical metal plane (discharge by indirect contact).
The EMC-5 Electrostatic Discharge Immunity (ESD) measurement system, specially designed to meet the requirements of the standards for direct and indirect discharge tests, in air and contact, consists of the following units:
-EMC-0510: Electrostatic discharge generator (ESD) 2 KV ÷ 8 KV
-EMC-0520: ESD measurement site
-EMC-0530: Set of signal and power cables.
-EMC-0540: Series of technical and educational manuals related to the equipment used.

OF.EMC-7



         
Immunity in Surge and Burst

The Surge and Burst EMC-06 interference immunity system, specially designed to meet the requirements of the standards, consists of the following units:
- EMC-0610: 4 KV Surge generator
- EMC-0620: 4 KV / 5 KHz Burst generator
- EMC-0630: Surge and Burst measurement site
- EMC-0640: Set of connection and power cables.
- EMC-0650: Series of technical and educational manuals related to the equipment used.

OF.EMC-8



         
Immunity to Magnetic Fields

Network frequency magnetic fields are ubiquitous, with high field strengths in the vicinity of power cables, transformers, electric motors or large power distribution systems.
Since magnetic fields can interfere with a variety of electrical and electronic devices and equipment, it is necessary to perform tests to ensure that these systems continue to function properly in the intended work environment. This is particularly important in electronic applications operating in safety areas.
Test of immunity to magnetic fields at 50 Hz
The purpose of the test is the verification of the immunity of equipment, individual devices or systems, to magnetic fields at network frequency (50 Hz).
The disturbance is created by a suitable generator connected to a ring antenna (loop) of appropriate size. The disturbance signal is variable between 1 A / m and 30 A / m according to the specifications indicated in the applicable standard.
The test is carried out by normally feeding the Device under examination (DUT), immersing it in the magnetic field at 50 Hz for 1 minute and taking note of the behavior of the same when the disturbance is applied.
The EMC-7 Magnetic Field Immunity measurement system, specially designed to operate according to the regulations, consists of the following units:
- EMC-0710: Magnetic Field Generator
- EMC-0720: Helmholtz Ring Antenna
- EMC-0730: Set of connection and power cables.
- EMC-0740: Series of technical and educational manuals related to the equipment used.

OF.EMC-9



         
Immunity to Gap and Tension Changes

Voltage gaps (DIPS) are short interruptions of the voltage supplied by the power supply network. They can be caused by faults in the network, in installations or by a sudden change in load on the network itself.
Voltage variations (decrease: sag: increment: swell) are fluctuations in the nominal value of the voltage supplied by the power supply network. They are caused by continuously variable loads connected to the network.
Electrical and electronic equipment can be affected, in a more or less sensitive way, by voltage gaps, short interruptions or variations in power supply voltage.
The purpose of the test is the verification of the immunity of equipment, individual devices or systems, to the effects on its functioning caused by sudden changes in voltage or by gradual variations of the same.
The Device under test (DUT) is tested for different test levels (eg 30%, 60% and 95% below the rated voltage of the equipment), for different durations of losses / interruptions (eg 10 ms., 100 ms., 5 s) and for different angles (eg 90 °, 270 °) of application of the disturbance with respect to the passage from zero of the alternating power signal.
The disturbance is created by an appropriate generator through which power is supplied to the DUT. The measurement system for the Immunity to Holes and Voltage Variations EMC-08, specially designed to operate according to the provisions of the standards, consists of the following units:
- EMC-0810: Holes Generator and Voltage Variations
- EMC-0820: Set of connection and power cables.
- EMC-0830: Series of technical and educational manuals related to the equipment used.

OF.EMC-10



         
Set of RF Sensors

If during an EMC pre-compliance test it is found that the emissions of the Device under test (DUT) occur at amplitude levels that exceed the limits established by national and international standards, it will be necessary to look for the emission sources to try to mitigate the problem.
It is often possible to find out the source of Elettro Magnetic emissions using near-field probes. The probes produce a voltage proportional to the magnetic and electric fields intercepted: the greater the energy is captured and the higher the output voltage.
However, before you can effectively use near field probes, you need to learn as much as possible about unwanted signals. For example, reducing the spectrum analyzer bandwidth resolution with respect to the typical 120 kHz frequency required by standards. When bandwidth is reduced, a modulation around a peak can be found. Modulation will tell you if there is more than one emission contributing to the excessive level.
The EMC-09 Field Proximity RF Sensors set works effectively in the detection of interference signals. It is composed of the following units:
- EMC-0910: H Field Sniffer
- EMC-0920: E Field Sniffer
- EMC-0930: Current Sniffer
- EMC-0940: Series of technical and educational manuals related to the equipment used.