Power Supply in Telecommunications

Frontmatter

1. General and Introduction

Abstract

Most telecommunications systems operate from a d.c. supply voltage. This voltage has to meet specific requirements with regard to voltage tolerance and AF/RF ripple. The public a.c. mains voltage must be converted to d.c. by rectifiers which are equipped with electronic regulators. This enables the rectifiers to supply the necessary stabilized voltage independently of variations in a.c. mains voltage and frequency as well as of varying load demands. Built-in filters ensure that the d.c. voltage is smoothed to meet specifications.

Hans Gumhalter

2. Requirements of Telecommunications Systems on the Power Supply

Abstract

Table 2.1 contains the data on power supplies which are important in connection with the features of communications systems. Line 1 of Table 2.1 shows the rated voltages for communications systems. A distinction is made between 24, 48 and 60 V systems. Modern systems are usually 48 or 60 V, the positive pole normally being earthed. The choice of voltages also depends on the safety regulations of the country in question. In Germany, direct voltages over 120 V and alternating voltages over 50 V are classed as ‘dangerous contact voltages’.

Hans Gumhalter

3. Operating Modes of a Direct Current Power Supply System

Abstract

Figure 3.1 gives an overview of the operating modes of d.c. power supply systems currently in application. Table 2.1 applies to the operating voltages of communications systems.

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4. Operating Modes of an Alternating Current Power Supply System

Abstract

The operating modes used for a.c. loads in communications systems are listed in Table 4.1.

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5. Public Mains

Abstract

It is important to know the characteristics of the public power supply system (distribution network) when operating telecommunications power supply systems. This chapter explains the factors to be considered and the line-side conditions for which the equipment is designed.

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6. Energy Storage

Abstract

An introduction to battery systems was presented in Section 1.4.

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7. Basic Circuits and Process Control

Abstract

With the half-wave rectifier (Fig. 7.1) only the positive half-waves of an alternating current are passed. This circuit is suitable for low output powers. More complex filtering is necessary to suppress interference voltages.

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8. Applications of Control Systems in Power Supply Devices

Abstract

This chapter treats the application of control engineering in modern power supply equipment in more detail. Some elementary correlations and terms in open-loop control and closed-loop control are presented for those readers for whom this part of the subject is not so familiar.

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9. Switching Mode Power Supplies

Abstract

At this point a selection of equipment will be described; they all employ the principle of pulse-width control.

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10. Thyristor Controlled Rectifiers

Abstract

At this point a selection of equipment will be described; they all employ the principle of phase-angle control.

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11. Magnetically Controlled Rectifiers

Abstract

Magnetically controlled rectifiers have been used in power supply systems for more than 40 years.

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12. D.C./D.C. Converter

Abstract

D.C./D.C. converters are designed either as single-height or double-height power supply units or as complete built in equipment; they all deliver constant controlled (component) supply voltages.

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13. D.C./A.C. Inverters

Abstract

At this point a selection of equipment will be described.

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14. Static UPS Systems

Abstract

At this point the introduction and basic circuits of static UPS systems (as in Sects. 1.7, 4.3 and 4.3.5) are recalled. A selection of the equipment will be described in Fig. 14.1. Different examples of types, series and power ranges of UPS-systems are listed in Table 14.1.

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15. Diesel Generating Sets

Abstract

An introduction to standby power supply systems (diesel generating sets) was presented in Sect. 4.2.1.

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16. Special Features for Transmission System Power Supplies

Abstract

In considering power supplies for long-range transmission systems it is necessary to distinguish between the following:

• power supply systems in telecommunication towers,
• power supply systems in ground communications stations and
• power supply systems independent of mains supplies.

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17. Grounding and Potential Equalization

Abstract

Grounding (earthing) embraces all the means and methods whereby conducting parts are connected to earth through a grounding system.

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18. Protective Measures

Abstract

To avoid accidents from electrical causes, the rules for the prevention of accidents of the professional association¹, the VDE regulations (e.g. DIN 57 100/VDE 0100) and all other safety rules should be observed.

Hans Gumhalter

Backmatter