Contents

	Welcome Note
	FTTX The next broadband wave
	Creating the Green Data Centre
	Protection systems in the Communications Network
	Patch-Free Cabling Solution
	Cat 6A is now Ratified

Protection systems in the Communications Network

Introduction

The importance of overvoltage protection has increased considerably over the past years. On one hand, this is due to growing demands placed on advanced communications systems that increasingly support voice, video and data transmissions. On the other, the deployment of electronics further into the network has resulted in miniaturization – with an increased integration density – and hence reduced electrical strength.

Connection and distribution technologies from ADC KRONE set a global standard and are supplemented by a powerful and flexible portfolio of protection solutions. Individual protection possibilities enable an optimum cost-to-benefit ratio and ensure maximum economic efficiency for the user.

Applications of overvoltage protection

Protection systems are used wherever communication lines are distributed and connected. Overvoltage protection fulfils various requirements, depending on the type of installation to be protected. In conventional switching equipment, overvoltage protection is used primarily to protect people. In highly sensitive electronic switching equipment installations, however, comprehensive protection measures are necessary in order to protect not just people, but also the valuable installation itself.

Overvoltage is undoubtedly the primary cause of faults, i.e. interference caused by electrical energy disturbances in communication lines. The term “overvoltage” often calls to mind thunderstorms releasing vast amounts of energy. However, even static discharges, which may appear to be harmless, can seriously affect signal transmission or even paralyse entire networks. Overvoltage in supply lines for centrally controlled process management and control systems can sometimes lead to immense damage and costs into the millions, or even to irrecoverable losses.

Different forms of overvoltage

Although the different forms of overvoltage have basically remained unchanged for many years, their causes and effects are subject to change. Overvoltage can be caused not only by reproducible interferences, but also by impulses that occur randomly. Reproducible excess voltages caused, for example, by capacitive or inductive switching, are often easy to localise and suppress.

Common Causes Of Damage
Electrostatic Discharge ESD (Lightning Strike)

In order to achieve efficient protection against excess voltages caused by non-reproducible interferences, a range of standards and recommendations can be adopted with a view to causes, duration and injection of such interferences into the system. Overvoltage in communication networks is usually the result of electromagnetic interference, equalising currents between different earth potentials or network short circuits.

Common Causes Of Damage
Electro Magnetic Coupling EMI (Indirect Lightning Strike)

This is caused by switching operations on neighbouring lines, the indirect effect of lightning or natural forces, or by human error. The direct effect of lightning on distribution equipment is an exception, because this type of equipment is usually installed indoors or in enclosures.

Common Causes Of Damage
Electro Magnetic Coupling EMI (Power Line)

The massive amount of energy involved in direct lightning strikes requires separate protection concepts and structural measures.

Apart from direct lightning strikes, however, interference by one of the following phenomena is more often than not the cause of damage to or destruction of communication systems:

• Indirect lightning impact
• Electromagnetic interference
• Inductiveor capacitive effects
• Electrostaticdischarge
• Contactwith live power lines

Common Causes Of Damage
Power Crossing DirectGalvanic Contact

These conditions often represent a high degree of danger to human life.

Recommendations for the application of protection measures

Overvoltage protection devices consist of components or protective circuits that limit interference to permissible values. Overvoltage protection devices must adapt to regional and local requirements. These requirements include operating conditions on the line and the protection requirements that result from the specific application area. Graded protective circuits with secondary protection elements should be used for incoming circuits on the exchange side and for terminal equipment (telephone, fax, modem), because in addition to personnel safety, sensitive electronic systems must also be protected. High voltage protection is usually sufficient for the line. In the event that active components are installed in a cross-connection cabinet, graded protective circuits are also recommended.

Costs and benefits for the user

When selecting suitable overvoltage protection modules, the cost-to-benefit ratio is of interest. The cost of installing protection modules contrasts favourably to the increased availability of the communication network and lower repair costs. An optimum selection on the part of the network operator results in minimum costs with maximum economic efficiency of the equipment. The extent of protection measures is based on the requirements and specifications from the network operator or the equipment manufacturer. In the idealised diagram shown here, the cost minimum is the point where the two curves meet. In order to protect personnel, applicable standards and regulations for setting up and operating telecommunications networks must also be observed. The applicable standards and/or regulations for setting up and operating telecommunication networks must also be observed to protect personnel.

Cost relationships

ADC KRONE supplies various types of protective circuits as follows

1. 3-point protection:  Protects telecom network from excess voltage (high voltage or secondary protection. Products include protection magazine with 3 pole GD tubes Three point protectionFive point protection
2. 5-point protection: Protects telecom network from excess voltage and current. Product include single pair protection plug
3. Graded 5-point Protection: The worlds only maintenance free protection device. Product include ComProtect BOD 180A4

For more information on ADC KRONE protection systems visit www.adckrone.com/in or write to venkatesh.mj@adckrone.com

MJ. Venkatesh
Technical Manager
Carrier Networks