Protection of Electrical Networks
Suitable for engineers, technicians, designers and operators working with electrical networks, this book discusses network structures and grounding systems, as well as problems that can occur in networks.
TABLE OF CONTENTS Protection of Electrical Networks
Chapter 1: Network Structures
Overview
Definition
Standard IEC 60038 defines voltage ratings as follows:
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Low voltage (LV): for a phase-to-phase voltage of between 100 V and 1,000 V, the standard ratings are: 400 V - 690 V - 1,000 V (at 50 Hz).
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Medium voltage (MV): for a phase-to-phase voltage between 1,000 V and 35 kV, the standard ratings are: 3.3 kV - 6.6 kV - 11 kV - 22 kV - 33 kV.
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High voltage (HV): for a phase-to-phase voltage between 35 kV and 230 kV, the standard ratings are: 45 kV - 66 kV - 110 kV - 132 kV - 150 kV - 220 kV.
In this chapter we will look at:
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types of HV and MV consumer substations;
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structure of MV networks inside a site;
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structure of LV networks inside a site;
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structure of systems with a back-up power supply.
Six standard examples of industrial network structures are given at the end of the chapter.
Each structure is commented upon and divided up so that each functional aspect can be considered.
(NC) means that the switch or circuit-breaker is closed in normal conditions.
(NO) means that the switch or circuit-breaker is open in normal conditions.
1.1 General structure of the private distribution network
Generally, with an HV power supply, a private distribution network comprises (see Figure 1-1):
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an HV consumer substation fed by one or more sources and made up of one or more busbars and circuit-breakers;
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an internal generation source;
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one or more HV/MV transformers;
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a...
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