NE 21 has been revised

from 2017-08-01

The NAMUR Recommendation NE 21 has been revised and may now be obtained from the NAMUR Office.

The document differs from NE 21 edition 2012-05-09 beside editorial adjustments and split in separate German and English versions as follows:

  • Chapter 3: the standards referred to have been updated
  • The term ‘operational behaviour’ has been added to the evaluation criteria
  • Table 1:
    - No. 1.1 Switching on-off during test has been added.
    - No. 1.2 The frequency range has been adjusted to suit operational frequencies.
    - No. 1.2 The size of the interference has been adjusted.
  • Table 2:
    - No. 2.2 The measurements at 100 kHz have been entered.
  • Table 3:
    - No. 3.2 The measurements at 100 kHz have been entered.
    - No. 3.7 The voltage drop has been added.
  • Table 4:
    - No. 4.2 The measurements at 100 kHz have been entered.
    - No. 4.7 The voltage drop has been added.
  • Annex: Annex B with its test report has been waived as no practical necessity has been in place.

Abstract NE 21 ‘Electromagnetic Compatibility of Equipment for Industrial Processes and Laboratory’
(Edition: 2017-08-01)

This recommendation describes uniform practical procedures for determining whether the devices used in laboratory and process control are immune to interference. The objective is to increase the functional safety of equipment.

Based on past experience, most of the interference effects are covered by this recommendation. For specific applications, it may be necessary for the manufacturer and the user to make special arrangements regarding the requirements with respect to type, scope and degree of immunity to interference.

General technical discussion of NE 21 has taken place and the recommendation has, in part, been revised. It has thus been adapted to take current marginal conditions and constraints also in combination with the used frequencies in members‘ companies into consideration.

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