In order to help customers become more familiar with an ever-increasing number of standards and changes to them, we are running an occasional feature, focussing our attention each time on a different standard! This month the spotlight is on EN61326.
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During the mid to late 1990s a number of product specific standards were developed which contained the emission and immunity requirements for particular products or product types.
Amongst these was EN61326, “Electrical equipment for measurement, control and laboratory use” embracing equipment intended for professional, industrial process and educational usage.
Measurement equipment includes that which measures or records either an electrical or non-electrical quantity by electrical methods. Examples could include temperature sensors and transducers. Also included within the scope is non-measuring equipment such as signal generators and measurement standards.
Electrical control equipment as defined within EN61326 controls one or more output values and includes industrial process measurement and control equipment. Typical examples could include process controllers, process instrumentation and analogue or digital indicators and recorders.
Finally, electrical laboratory equipment encompasses equipment which measures, indicates, monitors or analyses substances or is used to prepare materials. This equipment may be used in a laboratory or elsewhere.
In common with the product specific and generic standards, reference is made to basic standards for the test methods.
For emissions, the reference standard is EN55022 (CISPR 22) and the applicable limit line is either Class A or Class B depending upon the environment in which the equipment is intended to be used. The definitions of Class A and Class B are derived from the reference standard.
For immunity, the test methods and associated test levels are taken from the EN61000-4-X series of basic standards.
EN61326 takes a rather different approach to immunity testing in respect of the evaluation of test results through the performance criteria. The standard provides ‘minimum immunity test requirements’ which are broadly equivalent to those for the residential, commercial and light industrial environment as embodied in the appropriate generic standard.
The performance criteria themselves are specified from A to D unlike the conventional approach taken in most standards, which list criteria A to C.
The performance criterion to be used is dependent upon the function of equipment, its operation and crucially whether it is monitored or not. The categories defined within EN61326 are as follows:
The most stringent performance criteria relate to equipment having an “essential operation” (functional safety) and least stringent relate to equipment having a non-continuous operation.
An amendment was published to EN61326 in 1998, which increased the number of environments within the scope of the standard from one to three; these being an industrial location, a laboratory or test and measurement area and a controlled electromagnetic environment.
The newly created Annexes A and B provide immunity test levels for equipment intended to be used in an industrial environment and a controlled electromagnetic environment respectively.
This amendment also introduced Annex C, which provides immunity test requirements for portable test and measurement equipment.
A second amendment to EN61326 was published in 2000, resulting in the inclusion of Annex D. This introduced test configurations, operational conditions and immunity performance criteria primarily for oscilloscopes, logic analysers and digital multimeters.
A third amendment is currently being prepared, but as of May 2004 has not yet been published. Assuming that it mirrors the requirements of the recently published IEC61326:2002, this will see the introduction of Annexes E and F. Annex E provides information for the testing and assessment of portable test, measuring and monitoring equipment used in low voltage distribution systems and Annex F provides the same information, but for transducers with integrated or remote signal conditioning.
Last updated: 2004-Oct-19
