1. Why does a communications network require protection?
2. Why do today's networks require more protection than earlier equipment?
3. Why should I spend money on protection when the telephone company has already installed it at the demarcation point?
4. Why is it necessary to protect the network at so many points?
5. Do I still need protection in a low lightning area?
6. My switch manufacturer says that I have protection on each individual linecard. 
   Am I adequately protected?
7. Does a multi-story building have special requirements?
8. Do I need both AC and line protection?
9. What about off-premise extensions and spares?
10. Why should I choose Porta Systems' protection products?

 

 

 

 

 

1. A communications system must be protected for simple reasons of safety and economics. An unprotected line is hazardous to the people who work with it, and a liability to any equipment connected to it. Lightning, power crosses and other fluctuations in voltages, and current on an unprotected line can damage voice and data communications equipment and start fires.

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2. The microelectronics revolution has rendered obsolete the traditional forms of line protection that have served the communications industry for over 50 years. For instance, older telephone switches with their heavy electromechanical relays were able to withstand some degree of electrical overload. Today's digital systems, based on integrated circuitry, are extremely sensitive and easily damaged by surges. Thus, the more sophisticated our telecommunications systems become, the more they require proper protection. Also, the computer and related data communications equipment industries utilize sensitive electronics that require protection from over voltages and currents within the network.

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3. Your local telephone company will install the level of protection necessary to guard their own equipment and personnel. It's no longer their responsibility to protect your sensitive communications equipment, and their protection devices are not designed for this capability. In today's deregulated environment, you must expand upon existing protection to meet the needs of your own system.

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4. Today's communications systems have become very complex. Let's suppose that a business owns its own communications system and wiring. The local telephone company and the customer both install protection at the Building Entrance Terminal (typically found in the basement or utility room), where it guards against problems like lightning or other electrical surges that are entering the building from outside. But what about the hazards that originate inside an office building?

Let's suppose that a company has an office on the tenth floor of a commercial building. What happens when an electrician on the fifth floor accidentally places a live wire across their cable? A power surge could travel straight into the switch or data equipment, destroying expensive line cards or circuit components and the protection devices in the basement would not help at all. Remember, it is important to protect personnel and equipment at all of the network's vulnerable points.

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5. Absolutely. There is always the potential for surge damage, even in those areas of the world that are virtually lightning-free. In fact, very dry climates are especially prone to electrostatic build-up and discharge, making line protection a necessity. Furthermore, it would be unwise to discount the possibility that a downed power line could cross your nearby telephone cable, sending a dangerous surge into your equipment.

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6. There are at least two problems with the idea of relying solely upon integral line card protection:

1. This is secondary protection.
2. No protection is provided "upstream."

Not Primary

As secondary protection, circuitry that is incorporated on a switch linecard is not designed to handle high energy electrical surges such as lightning or power crosses. Such disturbances can involve thousands of amperes of current at thousands of volts and require the heavy duty construction of primary protectors. A typical lightning surge which is allowed to propagate without attenuation to the line card will, at the least, destroy the protection circuitry on the card and could easily damage other line cards or worse. Also, separate primary protectors typically protect against long duration, moderate intensity problems such as "glow mode" and "sneak current" which can cause line card protectors to ignite.

No Upstream Protection

Line card protection only provides its modest protection to circuitry that is after or downstream from the protector. This means that whatever cabling, cross connects, or other wiring/devices are between the switch and the outside world are left unprotected. A high voltage surge that occurs on one or more cable pairs outside the exchange facility will propagate down the cable seeking a path to ground. If a primary protector is not installed to provide a low impedance ground path, the surge will arc through to ground via the cable sheath, possibly damaging other conductors or destroying the cable altogether. Service personnel handling interconnections between the outside cabling and the switch are also in danger.

Finally, certain electrical disturbances are of such high magnitude and/or duration that any protector will be destroyed. Porta Systems protectors are designed to fail safely under such conditions, taking the line out of service while continuing to protect equipment and personnel. Once the disturbance has been removed, the protector is simply unplugged, discarded and a new one is inserted in its place. Try that with line card protection!

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7. Yes. In a multi-story building, cables typically run up through the walls and floors to the tenants upstairs. Any high current on these lines can create an extreme fire hazard. Therefore, "line-opening" type protection must be installed on the upper floors to prevent the heating and burning of wires that can result from high current flow on riser and feeder cables.

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8. Communications systems are typically connected to both indoor wiring and an electrical outlet. That means there are two unprotected pathways that can carry hazardous surges into the system.

In the past, a conscientious installer would attempt to protect the system using a surge protector at the electrical outlet and a termination/protection unit on the indoor wiring. However, because the units did not share a common ground, the system was subject to the dangers of ground potential difference.

On Porta Systems' Six-Plus™ a common ground is shared by the AC line and the voice/data line. This not only eliminates ground potential difference, but allows for the cascading of additional pairs using Porta Systems 6, 10 and 25-pair Protector Packs.

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9. Protect each and every cable pair or line entering your system, including off-premise extensions and spares. Keep in mind that every wire has the potential to carry a dangerous spike into the system. Even a line running underground is not safe, since lightning takes the most direct path to ground, which might turn out to be that cable. In a campus environment, it is also important to protect each point where the cable enters or exits a building. Do not make the mistake of installing outside cable protection, only to have a surge enter through the equipment side.

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10. Porta Systems has been a leader in the development of protection devices for voice and data networks. For over two decades we have continuously improved upon the field of protection technology, gaining widespread recognition for our sophisticated and innovative designs. As a result, Porta Systems can offer you the most comprehensive line of protection products for your communications network and a proven track record to stand behind it.

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