EN 60255-26 Measuring Relays and Protective Equipment - Part 26: Electromagnetic Compatibility Requirements

The European standard “EN 60255-26 Measuring relays and protection equipment - Part 26: Electromagnetic compatibility requirements” applies to measuring relays and protection equipment, taking into account the combination of devices used to create schemes for power system protection. This includes control, monitoring, communication and process interface equipment used with these systems.

This standard covers electromagnetic compatibility requirements for measuring relays and protection equipment. The tests specified in this standard are not required for equipment that does not contain electronic circuits, such as electromechanical relays. The requirements specified in this standard apply to measuring relays and protection equipment in new condition and all tests specified are type tests only.

The purpose of this standard is to specify limits and test methods for measuring relays and protection equipment with respect to electromagnetic emissions that may cause interference to other equipment. These emission limits represent electromagnetic compatibility requirements and have been selected to ensure that the disturbances produced by measuring relays and protection equipment normally operated in substations and power plants do not exceed a specified level that may prevent other equipment from operating as intended. Test requirements are specified for enclosures and auxiliary power supply ports.

This standard is to specify the immunity test requirements for measuring relays and protection equipment with respect to continuous and transient, conducted and radiated disturbances, including electrostatic discharges.

These test requirements represent electromagnetic compatibility immunity requirements and have been selected to provide an adequate immunity level for measuring relays and protection equipment normally operated in substations and power plants. Safety aspects are not addressed in this standard. In special cases, situations arise where disturbance levels may exceed the levels specified in this standard, for example when a hand-held transmitter or mobile telephone is used in close proximity to measuring relays and protection equipment. In these cases, special precautions and procedures may need to be applied.

For the purposes of this standard, the following terms and definitions apply:

• Analog output port is the port that generates analog output signal to drive actuators, analog panel meters, etc. It generally has a current or voltage less than or equal to 20 mA or 10 V direct current, respectively.
• Auxiliary equipment is equipment necessary to provide the signals required for normal operation of the equipment under test and to verify the performance of the equipment under test.
• The auxiliary power supply port is an alternating current or direct current auxiliary power input. Some advanced relays have a single auxiliary power supply port that can be powered by both AC and DC.
• Battery monitoring port is the port designed to connect to the station battery for battery voltage monitoring purposes.
• A binary input port is a port designed for inputs that are given an open or closed state by direct connection to an energizing quantity without any communication protocol.
• A binary output port is a port designed for outputs with an open or closed state given by direct connection to an energizing quantity without any communication protocol.
• Common mode is the mode between each active conductor and a specified reference, usually ground or the earth reference plane.
• Differential mode is the mode between any two of the specified set of active conductors.
• A grounding port is a point to which a cable designed to be connected to ground for functional or safety purposes can be connected.
• The enclosure port is the physical boundary of the equipment under test through which electromagnetic fields can propagate or impinge.
• Equipment under test refers to the equipment subjected to a test, including communication modules, plug-and-play power supplies, and similar accessories, unless otherwise stated.

Electromagnetic environmental levels should be selected to suit the most realistic installation and environmental conditions under which the device under test is expected to operate. Recommended test level selection, based on common installation practices, is given within the standard.

For example, Zone A is a severe electromagnetic environment. The installation is characterized by:

• Failure to suppress electrical fast transients or bursts in power supply and control and power circuits switched by relays and high-power contactors.
• Failure to separate industrial circuits from other circuits associated with environments of higher severity levels.
• No separation between power supply, control, signal and communication cables.
• Using common multi-core cables for control and signal lines.
• Connections that work as outdoor cables together with power cables, even extending to high-voltage equipment. A special case of this environment is the connection of electronic equipment to the telecommunications network in a densely populated area. There is no systematically constructed grounding network outside the electronic equipment, and the grounding system consists only of pipes or cables.

The outdoor area of ​​industrial process equipment, power plants, open-air high-voltage substation switchyards, and gas-insulated switchgear may represent this environment.

Our organization has a strong staff that closely follows the developments in science and technology in the world and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also test services in accordance with the standard “EN 60255-26 Measuring relays and protection equipment - Part 26: Electromagnetic compatibility requirements”.