Primary Protection
Primary Protection
Primary telecommunications protectors must be deployed at points where exposed twisted
pairs enter an office building or residence. This requirement is mandated in North America
by the National Electric Code (NEC) to protect end users from the hazards associated with
lightning and power cross conditions.
Primary protection is provided by the local exchange carrier and can be segregated into
three distinct categories:
•
•
Station protection — typically associated with a single twisted pair
Building entrance protection — typically associated with multiple (25 or more) twisted
pair
•
Central office protection — typically associated with numerous twisted pair feeding into a
switch
Station protectors provide primary protection for a single-dwelling residence or office. The
station protector is located at the Network Interface Unit (NIU), which acts as the point of
demarcation, separating the operating company’s lines from the customer’s.
Building entrance protection is accomplished by installing a multi-line distribution panel with
integrated overvoltage protection. These panels are normally located where multiple twisted
pairs enter a building.
A five-pin protection module plugged into a Main Distribution Frame (MDF) provides Central
and Remote Office protection. Like station and building entrance protection, the MDF is
located where exposed cables enter the switching office.
Teccor also offers a full line of five-pin protectors. For further details, contact factory at
protectionsystems@teccor.com or +1 972-580-7777.
Protection Requirements
Station protectors must be able to withstand 300 A 10x1000 surge events. The building
entrance protectors and CO protectors must be able to withstand 100 A 10x1000 surge
events. Figure 3.36 shows building entrance protector and CO protector asymmetrical
solutions. Figure 3.37 shows building entrance protector and CO protector balanced
solutions.
The following regulatory requirements apply:
•
•
•
UL 497
GR 974-CORE
ITU K.28
Primary Protection Reference Circuit
Figure 3.36 and Figure 3.37 show different configurations used in primary protection. Note
that the peak off-state voltage (VDRM) of any device intended for use in primary protection
applications should be greater than the potential of a Type B ringer superimposed on a
POTS (plain old telephone service) battery.
150 VRMS ꢁ2 + 56.6 VPK = 268.8 VPK
© 2002 Teccor Electronics
3 - 29
http://www.teccor.com
+1 972-580-7777
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SIDACtor Data Book and Design Guide
TECCOR [ TECCOR ELECTRONICS ]
