SIST CWA 14642:2004

CEN Workshop Agreement (CWA) - Electrical interface for domestic cogeneration - Requirements for distribution network connection for micro cogeneration systems for domestic use up to 16 A per phase in low-voltage distribution networks (230/400 V)

Micro-cogeneration is the generation of electricity and the recovery and use of the thermal energy
supplying the needs of domestic premises. This CEN Workshop Agreement covers the electrical
interface between the appliance and the low-voltage electrical network (nominal 230/400 V). Specific
elements like metering are not included. The intention of the CWA is to recommend future good
practice, noting that the CWA, local existing standards and practices may require modification in the
future due to larger market penetration and the associated return of experience.
NOTE The CWA reflects a pan-European view on best practice for the connection of micro-cogeneration; however it may not
be the most appropriate document for use in all countries and under all circumstances.
The following aspects are included in the scope:
· all technologies for micro-cogeneration are applicable;
· all generator types are applicable;
· the size is limited to a maximum of 16A per phase in a single low-voltage
installation (nominal 230/400V)
· both 3-phase and single-phase connections are applicable;
· connection is limited to low voltage networks;
· the electrical interface is the principal focus and this includes the method of
connection, the settings and protection requirements for connection, the operation
of the electrical interface under normal conditions, emergency shutdown,
distribution network-independent operation, start-up and distribution network
synchronisation;
· this document relates to the electrical interface only as existing standards and
directives apply to the other parts of the system;
· this document covers technical issues of connection.
NOTE The size is maybe increased up to 20 A (24 A) in accordance to the existing national standards in Germany, Austria,

Dogovor delavnice CEN (CWA) – Električni vmesnik za hišno soproizvodnjo – Zahteve za povezave razdelilnega omrežja za mikro soproizvodne sisteme za domačo uporabo do 16 A na fazo v nizkonapetostnem razdelilnem omrežju (230/400 V)

General Information

• Status: Withdrawn
• Publication Date: 31-Oct-2004
• Withdrawal Date: 08-Mar-2016
• ICS: 27.010 - Energy and heat transfer engineering in general
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 08-Mar-2016
• Due Date: 31-Mar-2016
• Completion Date: 09-Mar-2016
• Ref Project: CWA 14642:2003 - CEN Workshop Agreement (CWA) - Electrical interface for domestic cogeneration - Requirements for distribution network connection for micro cogeneration systems for domestic use up to 16 A per phase in low-voltage distribution networks (230/400 V)

Relations

• Child: SIST EN 50438:2008 - Requirements for the connection of micro-generators in parallel with public low-voltage distribution networks
• Effective Date: 01-May-2008

Standards Content (Sample)

SLOVENSKI STANDARD
SIST CWA 14642:2004
01-november-2004
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=DKWHYH]DSRYH]DYHUD]GHOLOQHJDRPUHåMD]DPLNURVRSURL]YRGQHVLVWHPH]D
GRPDþRXSRUDERGR$QDID]RYQL]NRQDSHWRVWQHPUD]GHOLOQHPRPUHåMX
9
CEN Workshop Agreement (CWA) - Electrical interface for domestic cogeneration -
Requirements for distribution network connection for micro cogeneration systems for
domestic use up to 16 A per phase in low-voltage distribution networks (230/400 V)
Ta slovenski standard je istoveten z: CWA 14642:2003
ICS:
27.010 Prenos energije in toplote na Energy and heat transfer
splošno engineering in general
SIST CWA 14642:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST CWA 14642:2004

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SIST CWA 14642:2004
CEN
CWA 14642
WORKSHOP
January 2003
AGREEMENT
ICS 27.010
English version
CEN Workshop Agreement (CWA) - Electrical interface for domestic
cogeneration - Requirements for distribution network connection for
micro cogeneration systems for domestic use up to 16 A per phase in
low-voltage distribution networks (230/400 V)
This CEN Workshop Agreement has been drafted and approved by a Workshop of representatives of interested parties, the constitution of
which is indicated in the foreword of this Workshop Agreement.
The formal process followed by the Workshop in the development of this Workshop Agreement has been endorsed by the National
Members of CEN but neither the National Members of CEN nor the CEN Management Centre can be held accountable for the technical
content of this CEN Workshop Agreement or possible conflicts with standards or legislation.
This CEN Workshop Agreement can in no way be held as being an official standard developed by CEN and its Members.
This CEN Workshop Agreement is publicly available as a reference document from the CEN Members National Standard Bodies.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members.
Ref. No. CWA 14642:2003  E

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CWA 14642:2003 (E)
Content
1 Scope . 7
2 References. 8
3 Terms and definitions. 9
4 Safety requirements . 13
4.1 General . 13
4.1.1 The electrical installation. 13
4.1.2 Electrical equipment. 14
4.2 Connection of the appliance . 14
4.3 Connection of multiple micro-cogeneration appliances . 14
4.4 Protection functions of the electrical interface . 14
4.4.1 Over-/Under-frequency . 15
4.4.2 Over-/Under-voltage . 15
4.4.3 Over-current protection . 16
4.4.4 Other protection criteria . 16
4.5 Earthing. 17
4.6 Residual current protection. 17
4.7 Re-connection of the appliance . 17
4.8 Synchronisation. 17
5 Power quality. 17
5.1 Electromagnetic emission / immunity. 17
5.2 DC injection. 17
5.3 Power factor. 17
5.4 Voltage changes and flicker. 17
5.5 Voltage distortion . 18
6 Operation and safety of the appliance. 18
6.1 General . 18
6.2 Information plate and labelling. 18
6.3 Maintenance & routine testing . 19
7 Commissioning . 19
7.1 General . 19
7.2 Installation. 19
2

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7.3 Notification procedure. 19
7.4 Decommission arrangements . 20
7.5 Replacement Arrangements . 20
8 Type testing and type certification. 20
8.1 Type testing. 20
8.2 Type certification micro-cogeneration appliance . 20
8.3 Type Certification of the electrical interface. 20
Annex 1: National requirements (2001 – informative) . 21
Austria. 21
Belgium . 21
France. 23
Germany . 24
Italy. 24
The Netherlands . 25
UK . 25
Annex 2: Notification sheets . 26
NOTIFICATION OF MICRO-COGENERATION INSTALLATION . 26
NOTIFICATION OF MICRO-COGENERATION APPLIANCE DECOMMISSIONING . 28
NOTIFICATION OF MICRO-COGENERATION APPLIANCE REPLACEMENT . 30
Annex 3: Abbreviations. 31
Annex 4: Bibliography. 32
Annex 5: CIRED summary of replies to Cen Workshop Agreement (informative) . 33
3

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CWA 14642:2003 (E)
Foreword
This CEN Workshop Agreement has been drafted and approved by a Workshop of representatives of
interested parties in September 2002, the constitution of which was supported by CEN following the
public call for participation made in February 2001.
A list of the individuals and organizations which supported the technical consensus represented by the
CEN Workshop Agreement is available from the CEN Management Centre. These organizations were
drawn from the following economic sectors: manufacturers, testing and certification institutes,
distribution network operators (DNO), European Commission.
The formal process followed by the Workshop in the development of the CEN Workshop Agreement
has been endorsed by the National Members of CEN but neither the National Members of CEN nor the
CEN Management Centre can be held accountable for the technical content of the CEN Workshop
Agreement or possible conflict with standards or legislation. This CEN Workshop Agreement is not yet
a standard developed by CEN and its members.
The final review/endorsement round for this CWA was started in August 2002 and was successfully
closed in November 2002.The final text of this CWA was submitted to CEN for publication on 15
November 2002.
This CEN Workshop Agreement is publicly available as a reference document from the National
Members of CEN: AENOR, AFNOR, BSI, COSMT, DIN, DS, ELOT, IBN/BIN, IPQ, IST, MSA, NEN,
NSAI, NSF, ON, SEE, SIS, SFS, SNV, and UNI.
Comments or suggestions from the users of the CEN Workshop Agreement are welcome and should
be addressed to the CEN Management Centre
Introduction
CHP, Combined Heat and Power, or cogeneration is the simultaneous production of heat and
electricity. This proven technology produced in the year 2001 around 10% of Europe’s electricity and
heat requirements.
In recent years “micro-cogeneration” systems below 11 kVA have been developed. Within the micro-
cogeneration technology one can differentiate between domestic applications (e.g. for households)
and non-domestic applications (e.g. for hotels or swimming pools). Due to the lower running hours,
saving on domestic cogeneration is quite different from commercial micro-cogeneration. In order to
maximise the environmental benefits of domestic cogeneration these systems should be thermally led.
Micro-cogeneration is still an emerging technology and as such, lacks an appropriate standard for the
electrical interface. Existing standards are applicable to other parts of a micro-cogeneration system.
The technology for micro-cogeneration can be fuel cells, small gas engines, thermo-electric modules
and Stirling engines (possibly in conjunction with heat pumps or solar boilers).
The expected growth of micro-cogeneration will follow the normal market penetration of a new
technology. There is a need to address the initial market uptake for micro-cogeneration and this is the
purpose of this document.
Generally electrical networks have been developed to be operated in a centralised manner, where
large power plants produce electricity that is transported over long distances to provide power to many
customers. In such a system the power flows in only one direction: from the power station through the
network and to the customer.
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With cogeneration systems the electricity can flow in two directions (from the cogeneration unit to the
network and from the network to the site where the cogeneration unit is located). This can be a
1
concern for the distribution utility , since the micro-cogeneration plant could be supplying energy into a
section of the DNOs network either under fault or normal operating conditions, this may create
problems for the safety of persons working on the network and the quality of the voltage supplied by
the network. A need for appropriate co-ordination and technical rules exists. The way this problem has
been dealt with so far varies from country to country. Whilst there are rules for distribution network
interconnection that are appropriate for larger scale cogeneration systems, they were not designed for
micro-cogeneration. In some European countries small-scale cogeneration systems can be connected
to the low voltage network. However, existing rules for small-scale less than 1 MWe maybe make it
onerous for the very small domestic micro-cogeneration systems to be operated.
If micro-cogeneration systems are not simple to connect and safe, they will never penetrate the
domestic market successfully. It is necessary to formulate technical specifications that solve all
technical issues at low costs. The specifications also need to be more straightforward and robust than
for industrial customers, because domestic consumers are not technically skilled and therefore need
more protection.
Widely accepted specifications will help to overcome the technical difficulties to connect micro-
cogeneration systems to electrical networks and to reduce the associated costs. Furthermore, it
should limit the risk of disputes between DNO and other parties (manufacturer, contractor and
customer). The intention of this document is not to change existing local standards or practices
immediately but is a recommendation of future good practice. It is built on growing experience of
micro-cogeneration in Europe.
LV electrical installations are covered by IEC 60364 and CLC HD 384. In some countries national or
local regulations apply, overriding these standards and the CWA.
This CEN Workshop Agreement applies to the electrical interface of micro-cogeneration systems for
domestic use, up to 16 A per phase. It deals with notification procedures as well as technical
specifications regarding safety and electrical co-ordination. Micro-cogeneration for domestic premises
will therefore require being a "fit and inform" process that meets all the necessary requirements of the
Distribution Network Operators.
Due to the practical difficulties as well as the lengthy procedure of developing an EN standard, it was
decided to start with a CEN Workshop Agreement and to use it as input for the normal standardization
process. As the CWA is a recommendation for good practice and not a standard national rules /
recommendations shall take priority over the recommendations in the CWA. It was agreed that CEN
will take over the Workshop Agreement, since CENELEC at that time did not have such a possibility.
Future development of the CWA towards an EN standard will be transferred to CENELEC.
———————
1
Utilities refers to private companies, national public or semi-public authorities responsible for the production and/or distribution
of electricity
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CWA participants
Advantica Technologies Ltd United Kingdom
AEA Technology United Kingdom
Alstom Research and Technology Centre United Kingdom
BG Group United Kingdom
GASTEC N.V. The Netherlands
COGEN Europe European organisation
Danish Standards Association Denmark
DEFU Denmark
DVGW-EBI Germany
EA Technology Ltd United Kingdom
- Serviços de Energia Descentralizada, S.A. Portugal
ECOGEN
ecopower energy solutions AG Switzerland
EDF R&D / Normalisation France
Electricité de France – Gaz de France Services France
Electricity Association Services United Kingdom
ENEL Distribuzione Italy
EnergieNed The Netherlands
GASTEC Certification B.V. The Netherlands
GAZ De France France
International Conference on Electricity Distribution CIRED European organisation
Laborelec Belgium
Netherlands Standardization Institute NEN The Netherlands
NUON The Netherlands
RWE Net AG Germany
Sigma Elektroteknisk Norway
TÜV Rheinland Product Safety Germany
Université Catholique de Louvain, Unité TERM – Groupe Belgium
Energie Biomasse
Vaillant GmbH Germany
NOTE Participation does not mean that all listed participants have agreed and accepted the final version of the CWA in all
points as some may be in contradiction to existing national rules or guidelines (see Annex 1).
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1 Scope
Micro-cogeneration is the generation of electricity and the recovery and use of the thermal energy
supplying the needs of domestic premises. This CEN Workshop Agreement covers the electrical
interface between the appliance and the low-voltage electrical network (nominal 230/400 V). Specific
elements like metering are not included. The intention of the CWA is to recommend future good
practice, noting that the CWA, local existing standards and practices may require modification in the
future due to larger market penetration and the associated return of experience.
NOTE The CWA reflects a pan-European view on best practice for the connection of micro-cogeneration; however it may not
be the most appropriate document for use in all countries and under all circumstances.
The following aspects are included in the scope:
• all technologies for micro-cogeneration are applicable;
• all generator types are applicable;
• the size is limited to a maximum of 16A per phase in a single low-voltage
installation (nominal 230/400V)
• both 3-phase and single-phase connections are applicable;
• connection is limited to low voltage networks;
• the electrical interface is the principal focus and this includes the method of
connection, the settings and protection requirements for connection, the operation
of the electrical interface under normal conditions, emergency shutdown,
distribution network-independent operation, start-up and distribution network
synchronisation;
• this document relates to the electrical interface only as existing standards and
directives apply to the other parts of the system;
• this document covers technical issues of connection.
NOTE The size is maybe increased up to 20 A (24 A) in accordance to the existing national standards in Germany, Austria,
Netherlands. It is permitted, in these countries, to feed a higher current than 16 A into the public grid. There are similar
requirements for the installation of special types of electrical appliances for domestic use (e.g. electrical water heater) with an
amperage higher than 16 A.
The following aspects are excluded from the scope:
• units exceeding nominal 230/400V;
• single phase units that exceed 16 A;
• multi phase units that exceed 16 A per phase;
• multiple units that exceed 16 A per phase in aggregate, for one installation;
• issues of revenue rebalancing, metering or other commercial matters;
• generators never to be connected to the supply networks.
The intention of the CWA is to insure that micro-cogeneration satisfies appropriate provisions for:
• safety of persons;
• information to electricians working inside the house
• voltage quality;
• reliability of supply;
• protection of the cogeneration unit.
Requirements for automatic disconnection and isolation regulations for safety purposes are included,
however the CWA does not cover the safety of DNO personnel or their contracted parties, as their
safety is a combination of the electrical conditions and working instructions, which is the responsibility
of the DNO. Labour safety of electricians working in the house is covered by other standards.
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2 References
This CEN Workshop Agreement incorporates provisions from other publications in dated or undated
reference,. These references are cited at the appropriate places in the text and the publications are
listed hereafter. For dated references, subsequent amendments to or revisions of any of these
publications apply to this CWA only when incorporated in it by amendment or revision. For undated
references the latest edition of the publication referred to applies (including amendments).
Publication Ref doc Title
EN 50081-1 Electromagnetic compatibility (EMC) – Generic emission standard –
Part 1: residential, commercial and light industry
EN 50082-1 EMC - Generic immunity standard –
Part 1: residential, commercial and light industry
EN 50160 Voltage characteristics of electricity supplied by public distribution systems
EN 50178 Electronic equipment for use in power installations
EN 55014-1 CISPR 14-1 Electromagnetic compatibility – Requirements for household appliances, electric tools
and similar apparatus –
Part 1: Emission – Product family standard
EN 55014-2 CISPR 14-2 EMC – Requirements for household appliances, electric tools and similar apparatus –
Part 2: Immunity – Product family standard
EN 55022 CISPR 22 Information technology equipment – Radio disturbance characteristics – Limits and
methods of measurement
EN 60335-1 Safety of household and similar electrical appliances –
Part 1: General requirements
EN 60730 IEC 60730 Automatic electrical controls for household and similar use
EN 61000-3-2 IEC 61000-3-2 EMC – Part 3-2: Limits -
Limits for harmonic current emissions (equipment input current up to and including 16
A per phase)
EN 61000-3-3 IEC 61000-3-3 EMC - Part 3-3: Limits -
Limitation of voltage fluctuations and flicker in low-voltage supply systems for
equipment with rated current up to 16 A
IEC 61000-6-1 Electromagnetic compatibility (EMC) - Part 6: Generic standards - Section 1: Immunity
for residential, commercial and light-industrial environments
IEC 61000-6-3 Electromagnetic compatibility (EMC) - Part 6: Generic standards - Section 3: Emission
standard for residential, commercial and light-industrial environments
IEC 61009-1 Residual current operated circuit-breakers with integral over-current protection for
household and similar uses (RCBOs) - Part 1: General rules
HD 384 IEC 60364 Electrical installations of buildings
modified
IEC 60050 International Electrotechnical Vocabulary (IEV)
- 151: Electrical and magnetic devices
- 195: Earthing and protection against electrical shock
- 411: Rotating machinery
- 442: Electrical accessories
- 448: Power system protection
- 601: Generation, transmission and distribution of electricity - General
- 603: Generation, transmission and distribution of electricity
     – Power systems planning and management
- 811: Electric traction
- 826: Electric installations of buildings
IEC 61140 Protection against electric shock – Common aspects for installation and equipment
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2
3 Terms and definitions
For the purpose of this CWA, the following definitions apply.
Appliance
An assembly of components to fulfil one or more functions and provided with a cover to protect the
user from hazards and the assembly from damage. To exchange energy, information, etc., an
appliance has connecting electric wires, fuels supply, water pipes and flue gas pipes etc.
For a micro-cogeneration appliance, the typical assembly consists of

For gas engines and Stirling engines, an engine to convert fuel to mechanical power,
mechanical to electrical conversion (generator, alternator, and/or inverter), electrical interface
(synchronisation device, inverter, interface protection).

For fuel cells, typical systems consist of a chemical-to-electrical power conversion, an inverter
and electrical interface.
The electrical interface monitoring- and control-functions may be incorporated into the micro-
cogeneration unit, or may be fitted as a discrete remotely mounted device. In either case the micro-
cogeneration unit and its electrical interface comprise the appliance and must contain also an isolating
switch.

Micro Cogeneration System Flue Gas
Heat
Electrical Alternator Prime Mover
Output
Electrical connection
Interface
Appliance
Fuel Supply
Figure 1:
Micro-cogeneration system (example)
Appliance fault current
The contribution from the appliance to the current flowing to the fault
Automatic reclosing equipment
Automatic equipment that is designed to initiate the reclosing of circuit-breaker(s) after operation of the
protection on the associated circuit
Certified appliance
An appliance that meets the product certification requirements
Clearing time
The clearing time is the time between the start of an abnormal condition and the micro-cogeneration
unit ceasing to energise the installation or network
———————
2
where possible IEC Multilingual Dictionary (on CD) is used
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Cogeneration (CHP: combined heat and power)
The generation of electricity by an energy conversion system and the concurrent use of the associated
thermal energy from the conversion system as an auxiliary energy source
Commissioning
The process by which a power plant, apparatus, or building is approved for operation based on
observed or measured operation that meets design specifications
Contracted person
The person who holds the contract for electricity connection at the house, where the micro-
cogeneration appliance is installed
Decommissioning
The process of removing an appliance, apparatus, equipment, building, or facility from operation
Decoupling protection
Comprises all functions including loss of mains protection
Disconnection (automatic)
The automatic disconnection of the supply from the installation, or a discrete section of it
Distribution Network (DN)
The electrical network transporting electricity in medium and low voltages between the transmission
network and the connected customer
Distribution Network Operator (DNO)
The company responsible for operating, maintaining, managing connections and investing in the
distribution network
Earth fault
The occurrence of a conductive path between a live conductor and the Earth
Domestic electrical installation
An assembly of electrical equipment that is used inside the domestic premises for the distribution
and/or use of electric energy except the cogeneration appliance itself (fuse – meter - switchboard –
installation)
The following diagram is for illustration only
Electrical Installation
Micro Cogeneration
Appliance
kWh
Figure 2:
Domestic electrical installation together with the micro-cogeneration appliance (example).
Electrical interface
Those parts of a cogeneration unit’s software and hardware that interact with the electrical installation
and network through the terminals of the unit
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Electricity exports
The electric energy generated in an electrical installation and flowing to the distribution network
Electricity supply system
All installations and plants provided for the purpose of generating, transmitting and distributing
electricity
Fuel cell
An electrochemical device that converts chemical energy directly into heat and electricity
Gas engine
An internal combustion engine modified or specifically designed to run on gaseous fuel
Generating unit
A device for transforming mechanical, thermal or chemical energy into electricity
Installation (of the appliance)
The placement and connection of a micro-cogeneration appliance
Internal Combustion Engine
An engine in which combustion of the fuel takes place in a confined space, providing expanding gases
that are used directly to provide mechanical power
Inverter
A static converter for the conversion of direct current to alternating current
Island (in a power system)
A portion of a power system, that is disconnected from the remainder of the system, but remains
energized
Islanding, intended
This occurs when the installation is operated intentionally to supply electricity to the consumer when
the network is temporarily unavailable
Islanding, unintended
This occurs when the network fails and the unit continues to operate in a grid connected manner
Islanding (network splitting)
The process whereby a power system is split into two or more islands
NOTE :– Islanding is either a deliberate emergency measure, or the result of automatic protection or control action, or the result
of human error
Isolation
The disconnection of all phases and neutral from an apparatus for safety and accessibility reasons.
Once the appliance has been isolated and shut down it can be safely accessed
Kinematic Stirling Engines
In this design of engine, the piston(s) are driven through connecting rods and a crankshaft, swash
plate or other means
...