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Their levels of electromagnetic compatibility must be sufficient to ensure their non-susceptibility to electrical interference, and non-interference with any nearby or connected electrical equipment. Additionally, because of their role within a facility, their performance quality must be enough to protect their critical load from mains-borne damaging effects.
For the UK, the most important legislation covering these aspects of a UPS installation is contained within the UPS Standard EN 62040 and the Energy Network Association’s Engineering Recommendation ER G5/4-1. Below, we look at these standards, then briefly review others that are also relevant to UPSs and their batteries.
The UPS Standard EN 62040 comprises three parts:
- BS-EN 62040 - Part 1 (General and Safety Requirements)
- BS-EN 62040 - Part 2 (EMC-Electromagnetic Compatibility)
- BS-EN 62040 - Part 3 (Performance & Test Requirements)
Part 1 – General and safety requirements: This standard applies to electronic indirect AC converter systems with an electrical energy storage device in the DC link. The primary function of the UPSs covered by this standard is to ensure continuity of an alternating current power source. The UPS systems may also improve the power quality of the power source by keeping it within specified characteristics.
This standard is applicable to movable, stationary, fixed and built-in UPSs for distribution systems up to 1000Vac. It applies to UPSs intended for installation in any operator-accessible area and specifies requirements to ensure safety for operators and non-specialists who may come into contact with the equipment and, where specially stated, for service personnel.
The standard is intended to ensure the safety of installed equipment, either standalone or as a system of interconnected units, subject to installing, operating and maintaining the equipment as prescribed by the manufacturer. It does not cover UPSs based on rotating machines. EN 62040-Part 1 is to be used in conjunction with EN 60950:2006 “Information technology equipment – Safety.”
Part 2 – Electromagnetic compatibility: This EMC standard applies to single UPSs installed in any operator accessible area or in separated electrical locations, connected to either industrial or public low voltage supply networks. This EMC standard takes precedence over all aspects of the Generic standards and no additional testing is necessary.
The requirements have been selected to ensure adequate levels of electromagnetic compatibility (EMC) for UPSs in public and industrial locations. These levels cannot however cover extreme cases which may occur in any location, but with extremely low probability of occurrence. It considers the differing test conditions necessary for UPSs of all physical sizes and power ratings.
A UPS unit or system must meet this standard’s relevant requirements as a stand-alone product. EMC phenomena produced by any customer's load connected to the UPS equipment’s output will not be considered. Special installation environments are not covered, nor are UPS fault conditions considered. This standard does not cover UPSs based on rotating machines.
Part 3 – Performance: The standard applies to electronic indirect AC converter systems with an electrical energy storage device in the DC link. The primary function of the UPS covered by this standard is to ensure continuity of an alternating current power source. The UPS systems may also improve the incoming supply power quality by keeping it within specified characteristics. The performance requirements of this standard are for UPSs within the scope of EN 62040-1.
The standard applies to UPSs with:
- Single or three phase, fixed frequency, 50/60Hz AC output voltage
- Single or three phase input voltage
- Electrical energy storage device in the DC link, if not otherwise specified
- With rated voltage not exceeding 1000Vac
- Movable, stationary or fixed equipment
This standard’s specifics:
- Characteristics of the equipment
- Test methods
- Minimum performance levels.
Energy Networks Association ER G5/4-1
The Energy Networks Association states that satisfactory operation of the electricity supply system and user’s equipment is only obtained where electromagnetic compatibility (EMC) between them exists. By limiting the harmonic emissions of customers’ non-linear loads and generating plant, the Engineering Recommendation G5/4-1 helps to fulfil the technical objective of the UK EMC Regulations.
These Regulations seek to limit the voltage distortion present in distribution networks to below levels at which equipment function and performance are likely to be impaired. Equipment immunity levels are based on a total voltage harmonic distortion (THDv) of 5% in 400V systems. Engineering Recommendation G5/4-1 sets the planning levels for harmonic voltage distortion to be used while connecting non-linear equipment to the supply system.
While harmonic distortion limits are not governed by statute, it is incumbent upon the electrical design consultants and manufacturers to ensure emissions of equipment connected to the supply system do not exceed the planning levels set by G5/4-1, and that such harmonic distortions are agreeable to the Network Operating Company (NOC).
Other standards relevant to UPS installations
While the above standards cover the core issues of UPS safety, performance and EMC compliance, there are many other standards that UPS installers and owners must consider; most of these are summarised in Table 1.
Additionally, there are the RoHS (2011/65/EU “Restriction of the use of certain Hazardous Substances in Electronic Equipment”) and WEEE (2012/19EC “Waste of Electrical and Electronic Equipment”) 2018 Directives; however, the RoHS Directive does not mention UPSs or energy conversion equipment, so does not directly apply to UPS systems.
Finally, there is the consideration that UPSs depend on batteries, which are subject to their own standards and obligations. Table 2 shows the standards relevant to Lead-Acid batteries, which remain as the most-widely used type for UPSs.
About the author:
Alex Emms is Operations Director for Uninterruptible Power Supplies Ltd. Alex has more than 28 years’ experience of the UK power protection business and 18 years’ service at UPS Ltd. Alex started out as a Field Service Engineer, progressing to Senior Engineer, Supervisor, Service Manager and now Operations Director.
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