CE MARKING EXPLANATION

What is Marking?

The EMC Directive 89/336/EEC became mandatory on January 1, 1996, and it stands for Electromagnetic Compatibility. EU (European Union ) defined EMC as the ability of a device, unit or equipment, or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to any devices in that environment. This encompasses both immunity to outside noise (function satisfactorily), and emission of noise (without introducing intolerable disturbances). For this reason CENELEC (European Committee for Electrotechnical Standardization) put out two different standards.

The Generic Immunity Standard EN 50082-1, and Generic Emission Standard EN 50081-1 from 1991 for Residential, Commercial, and Light Industrial environment. This has been harmonized in 1993 for Heavy Industrial environment becoming EN 50081-2 (Emission), and EN 50082-2 (Immunity). EN 50081-1:1991 Generic Emission Standard has two parts, Radiated Emission and Conducted Emission regulated by EN 55022, comparable to FCC part 15 in US.

The Radiated Emission deals with the electromagnetic field emitted by any electronic circuit that performs a switching sequence, and this increases if an antenna, consisting of I/O cables, is present. The test is performed between 30 to 230 MHz with a limit of 30 dBuV/m from 10 meters distance, and followed by 230 to 1,000 MHz with a limit of 37 dBuV/m from 10 meters distance for Commercial environment.

For Heavy Industry environments the distance changes to 30 meters.

Conducted Emission refers to the noise that is generated into the power lines, and causes interference at frequencies, between 0.15 to 30 MHz with limits of 60 dBuV quasi peak.

EN 50082-1:1991 Generic Immunity Standard consist of Electro Static Discharge (ESD), Radio Frequency (RF) and Electric Fast-Transient Burst (EFT).

Electro Static Discharge deals with the static charges that can build up in normal operation to several kilovolts and stresses the electronic components. The test is performed with 4 kV for Direct Discharge and 8 kV for Air Discharge.

The RF Immunity refers to the ability of the equipment to work undisturbed in a RF field (electromagnetic field) between 27 to 1,000 MHz, with 80% AM (amplitude modulation), and for Light industrial environments a 3 V/m Stress level is used, or 10 V/m for Heavy industrial environment.

In every day life any RF transmitter (2 way portable radio) that has a field higher than 1 or 10 V/m may disturb your device. If the power is known the field strength can be easily determined.

E = Electric Field in V/m, Pt = Transmitter Power in watts, and D = Distance from Transmitter to device in meters. Electric field in V/m function of Power and Distance from source.

Pt w	@1m	@2m	@3m	@4m	@5m	@6m	@7m	@8m	@9m
½	3.9	1.9
1	5.5	2.7	1.8
2	7.7	3.9	2.6	1.9
3	9.5	4.7	3.2	2.4	1.9
4	11.0	5.5	3.7	2.7	2.2	1.8
5	12.3	6.1	4.1	3.1	2.5	2.0	1.8
7	14.5	7.2	4.8	3.6	2.9	2.4	2.1	1.8
10	17.3	8.7	5.8	4.3	3.5	2.9	2.5	2.3	1.9

Fast-Transient Burst is related to the high voltage transients developed on the powerlines as a result of switching heavy equipment, lightning, and power outages. Test are performed with 1 kV burst at 5 kHz for power lines, and 0.5 kV burst to signal lines in case of Light industrial equipment, or 2 kV burst for power, and 1 kV to signal lines for Heavy industrial equipment.

As manufacturers we end up with Printed Circuit Boards (PCB) having 4, 6, or 8 layers, attempting to minimize emission and immunity, or using filters for I/O lines to improve the performance of our devices, and accomplish EMC compliance, for the European Community. Resulting in a more accurate and much more stable device.

The Low-Voltage Directive 73/23/EEC became mandatory on January 1, 1997, and has been regulated by EN 61010-1:1993 Safety requirements for electrical equipment, control, and laboratory use. Manufacturers of electronic equipment have become accustomed to the idea that safety approvals are necessary, or at least desirable, for their products. Fortunately, awareness of the severe hazards associated with electrical equipment and of the need to meet product safety standards is on the rise. Comparable standards in US are UL 1950, and in Canada CSA C22.2 No. 950-95.

Safety has been accomplished by design in one of the three Classes of equipment.

Class I equipment, where protection against electric shock is achieved by Basic Insulation and connection to the Protective Earthing Conductor (Ground) in the building wiring of parts that user gets in contact with in normal operation.

Class II equipment, provides protection against electric shock by increase of insulation from Basic to Double Insulation.

Class III equipment, are relying on the supply voltage that should not be Hazardous, being below 60 Vdc, 42.4 V peak, or 30 V rms.

Basic or Double Insulation are been accomplished by keeping certain spacing between main supply/high voltage and low voltage. These are established in the standard function of the working voltage, material, and transient voltages, for example at 300 V ac, with 2.5 kV transients, Basic Insulation requires 1.5 mm spacing but for Double Insulation 3.3 mm is required.

The next important issue is the installation environment, which is defined as Installation Category, or Overvoltage Category.

Installation Category I is for equipment used in residential environment, were transient voltages are not higher than 1.5 kV at 250 V ac supply.

For permanently connected equipment that is used in industrial environment Category II and III are recommended, where Category II specifies transients up to 2.5 kV, and Category III specifies transients up to 4.0 kV at 250 V ac supply.

Components that are connected directly on main supply/high voltage need special attention since we are relying on their integrity for safety. The best solution is if these components have a European approval, like VDE or TUV.

The Safety standards do not stop here; they are also addressing the Labeling/Marking, and Manual/Documentation aspect of safety. This consists in providing the customer with warnings in regards to safe installation and operation, as well as accurate information and suggestions in regards to over current protection devices. As a safety issue we need to provide or recommend installation of a switch/breaker as means of disconnect from power in emergency situations. It is clear that the standard is not addressing only the design aspect of safety, but also the liability of the manufacturer of equipment, or device.