High Speed Transmission Equipment
Protection Circuitry
Longitudinal protection is required at the Central Office Terminal (COT) interface because of
the ground connection used with loop powering. (Figure 3.14) Two P1800SC MC SIDACtor
devices provide overvoltage protection and two F1250T TeleLink fuses (one on Tip, one on
Ring) provide overcurrent protection. For the U-interface side of the coupling transformer,
the illustration shows the P0080SA MC SIDACtor device used for additional overvoltage
protection.
Central Office Terminal (COT) Interface
F1250T
Tip
Tip1
P1800SC MC
Ring1
Tip2
U-Interface
P0080SA
P1800SC MC
Ring2
Ring
F1250T
Power
Source
Figure 3.14 Pair Gain COT Protection
For Customer Premises (CP) and Remote Terminal (RT) interfaces where an earth ground
connection is not used, only metallic protection is required. Figure 3.15 shows metallic
protection satisfied using a single P3100SC MC across Tip and Ring and a single F1250T
on either Tip or Ring to satisfy metallic protection.
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© 2002 Teccor Electronics
SIDACtor Data Book and Design Guide
®
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