Medium voltage products
Technical guide
The MV/LV transformer substations
(passive users)
,
,Contents
2 1. The MV/LV transformer substations 37 6. Diagram of user system for connection and
2 1.1 Introduction MV switchgear
37 6.1 Diagram of the user installation
2 1.2 Reference standard and documentation 40 6.2 MV switchgear solutions
3 1.3 Traditional definitions and types 42 7. Power transformers
4 2. Design and construction specifications of the 48 7.1 Main characteristics
substation 46 7.2 Choice of transformers based on
4 2.1 Connection of the substation energy losses and efficiency
5 2.2 Structure of the substation 46 7.3 Efficiency requirements and classes for
6 2.3 Construction solutions transformers
7 2.4 Main requirements 49 7.4 Selection criteria for transformers based
9 2.5 Characteristics of the structure on capitalization of the losses
9 Structural specifications 49 7.5 Example of a transformer for a transformation
9 Specifications for seismic action substation
13 Specifications for fire action 51 7.6 Level of noise in the transformers
14 2.6 Thermal sizing and ventilation 51 7.7 Losses in the substation
15 2.7 Artificial lighting 52 8. LV Switchgear and Systems
15 2.8 Electrical cables in the substation: position, entry 52 8.1 Connection of the transformer and the LV
points and switchgear
separation of the circuits 52 8.2 LV switchgear
16 2.9 Earthing systems 54 9. Prefabricated substations
18 2.10 Earthing devices required by the 56 10. Other requirements of the substation electrical
connection system
19 2.11 Rating plates, warnings and diagrams 56 10.1 Overvoltages
22 3. Schematic diagrams of the connection 56 10.2 Harmonics and electrical and magnetic fields
23 4. Sizing and choice of the 59 11. Request for connection
switchgear and components 60 12. Inspections and tests in situ prior to putting
23 4.1 Disconnectors, switch-disconnectors, into service
multifunction devices 61 13. Maintenance of the electrical substation
26 4.2 Circuit-breakers 65 14. Example of substation design - electrical part
27 4.3 Measuring and protection transformers 65 14.1 Estimate of the power supplied to a
27 Inductive transformers small industrial factory
(TA-I, TA-T, TO, TV-I) 67 14.2 Calculation of short circuit and coordination
27 Inductive current transformers of the protections
(TA-I, TA-T, TO) 67 Theory behind calculation of the
30 Inductive voltage transformers (TV-I) short circuit current
31 Non-inductive current and voltage sensors 71 Sizing the electrical installation
(TA-NI, TV-NI) and coordination of the protections
32 5. Protection relays 80 15. Conclusion of the example and selection of
the switchgear: the ABB offer
1
, 1. Medium voltage/low voltage (MV/LV)
transformer substations
1.1 Introduction 1.2 Reference standard and
The subject of this Technical Guide is MV/LV substations;
in accordance with the reference standard, the discussion
documentation
will be limited to substations with installed power limited to The general picture providing an overview of the key reference
2000 kVA or two 1000 kVA MV/LV transformers. regulations relating to the design and construction of a MV/LV
The purpose of this guide is to give an overview of the substation is shown in the following figure.
guidelines and requirements specified by current regulations As you can see, the overview is complex, but on the other
for the design and construction of substations in order hand the MV/LV electrical substation is the synthesis of
to guide the designer and the user to the correct system several design activities (electrical, mechanical, construction,
choices. installation, etc.) and it is therefore also necessary to consider
The document will only touch on a few topics such as the fire prevention laws on safety and construction materials in
thee sizing of the earthing system and the building aspects, order to obtain a workmanlike result.
for further details on which you are referred to the specific
regulations.
Lastly, the document does not deal with issues related to
active Users, in other words those that produce alternating
current electricity with parallel operation (even temporary)
with the network.
Legislation for
System construction
standards for products Fire Prevention
activity and legislation
maintenance
Standards
Legislation for
and product
the prevention
guidelines for
of accidents in
switchgear and
the workplace
components
CEI 0-16 EMC legislation
CEI EN 61936-1 CEI EN 50522
2
Technical guide
The MV/LV transformer substations
(passive users)
,
,Contents
2 1. The MV/LV transformer substations 37 6. Diagram of user system for connection and
2 1.1 Introduction MV switchgear
37 6.1 Diagram of the user installation
2 1.2 Reference standard and documentation 40 6.2 MV switchgear solutions
3 1.3 Traditional definitions and types 42 7. Power transformers
4 2. Design and construction specifications of the 48 7.1 Main characteristics
substation 46 7.2 Choice of transformers based on
4 2.1 Connection of the substation energy losses and efficiency
5 2.2 Structure of the substation 46 7.3 Efficiency requirements and classes for
6 2.3 Construction solutions transformers
7 2.4 Main requirements 49 7.4 Selection criteria for transformers based
9 2.5 Characteristics of the structure on capitalization of the losses
9 Structural specifications 49 7.5 Example of a transformer for a transformation
9 Specifications for seismic action substation
13 Specifications for fire action 51 7.6 Level of noise in the transformers
14 2.6 Thermal sizing and ventilation 51 7.7 Losses in the substation
15 2.7 Artificial lighting 52 8. LV Switchgear and Systems
15 2.8 Electrical cables in the substation: position, entry 52 8.1 Connection of the transformer and the LV
points and switchgear
separation of the circuits 52 8.2 LV switchgear
16 2.9 Earthing systems 54 9. Prefabricated substations
18 2.10 Earthing devices required by the 56 10. Other requirements of the substation electrical
connection system
19 2.11 Rating plates, warnings and diagrams 56 10.1 Overvoltages
22 3. Schematic diagrams of the connection 56 10.2 Harmonics and electrical and magnetic fields
23 4. Sizing and choice of the 59 11. Request for connection
switchgear and components 60 12. Inspections and tests in situ prior to putting
23 4.1 Disconnectors, switch-disconnectors, into service
multifunction devices 61 13. Maintenance of the electrical substation
26 4.2 Circuit-breakers 65 14. Example of substation design - electrical part
27 4.3 Measuring and protection transformers 65 14.1 Estimate of the power supplied to a
27 Inductive transformers small industrial factory
(TA-I, TA-T, TO, TV-I) 67 14.2 Calculation of short circuit and coordination
27 Inductive current transformers of the protections
(TA-I, TA-T, TO) 67 Theory behind calculation of the
30 Inductive voltage transformers (TV-I) short circuit current
31 Non-inductive current and voltage sensors 71 Sizing the electrical installation
(TA-NI, TV-NI) and coordination of the protections
32 5. Protection relays 80 15. Conclusion of the example and selection of
the switchgear: the ABB offer
1
, 1. Medium voltage/low voltage (MV/LV)
transformer substations
1.1 Introduction 1.2 Reference standard and
The subject of this Technical Guide is MV/LV substations;
in accordance with the reference standard, the discussion
documentation
will be limited to substations with installed power limited to The general picture providing an overview of the key reference
2000 kVA or two 1000 kVA MV/LV transformers. regulations relating to the design and construction of a MV/LV
The purpose of this guide is to give an overview of the substation is shown in the following figure.
guidelines and requirements specified by current regulations As you can see, the overview is complex, but on the other
for the design and construction of substations in order hand the MV/LV electrical substation is the synthesis of
to guide the designer and the user to the correct system several design activities (electrical, mechanical, construction,
choices. installation, etc.) and it is therefore also necessary to consider
The document will only touch on a few topics such as the fire prevention laws on safety and construction materials in
thee sizing of the earthing system and the building aspects, order to obtain a workmanlike result.
for further details on which you are referred to the specific
regulations.
Lastly, the document does not deal with issues related to
active Users, in other words those that produce alternating
current electricity with parallel operation (even temporary)
with the network.
Legislation for
System construction
standards for products Fire Prevention
activity and legislation
maintenance
Standards
Legislation for
and product
the prevention
guidelines for
of accidents in
switchgear and
the workplace
components
CEI 0-16 EMC legislation
CEI EN 61936-1 CEI EN 50522
2
