ELECTRICAL PROTECTION: SYSTEM 85 AND DEFINITY GENERIC 2 WITH TRADITIONAL MODULES
3-5
Sneak-Current Device: Fuse
A sneak-current fuse is a fuse that melts when currents of .35A (for 4 hours) to 5.25A (for more than 10
seconds) reach it. Sneak-current fuses may be installed before or after the network interface (NI) in
series with the primary protector. Sneak-current fuses operate independently of the primary protector
and must be installed after it.
NOTE:
AT&T protector units that start with the number 4 are equipped with a heat coil to provide
both sneak-current and overvoltage protection.
ENHANCED PRIMARY PROTECTION
Enhanced primary protectors are protectors that operate at lower voltage or current levels than primary
protectors.
SECONDARY PROTECTION
Secondary protection, such as a data-link protector (DLP), provides additional protection for equipment
with a specific vulnerability. A DLP is an isolation transformer that provides protection for digital
terminals by isolating the low-impedance, phantom-powered circuit from an exposed loop. Local power
must be provided if the digital terminals are to be port-powered.
RECOMMENDED PROTECTORS
Following are recommended electrical protectors that can be used for primary, enhanced primary, and
secondary applications. With the exception of the 79A sneak-current fuses, all of the following primary
and enhanced primary protector units plug into 188 panels.
PRIMARY PROTECTORS
The following AT&T primary protector units are recommended for the protection of analog circuits.
●
3B1A — carbon block protector unit
●
3B1E-W — gas tube protector unit
●
3C1S — solid-state, overvoltage protector unit for analog circuits
●
4B1C — carbon-block and heat-coil protector unit
●
4B1E-W — gas-tube and heat-coil protector unit
●
4C1S — solid-state, overvoltage protector unit for analog circuits and heat-coil protector unit
Summary of Contents for 9601
Page 1: ...555 104 630 Issue 2 June 1991 DEFINITY Communications SystemGeneric 2 and System 85 Wiring ...
Page 57: ...2 34 MDF IDF DESIGN SYSTEM 85 AND DEFINITY GENERIC 2 WITH TRADITIONAL MODULES ...
Page 67: ...3 10 ELECTRICAL PROTECTION SYSTEM 85 AND DEFINITY GENERIC 2 WITH TRADITIONAL MODULES ...
Page 73: ...4 6 PORT PACKS DCP REPEATERS SYSTEM 85 AND DEFINITY GENERIC 2 WITH TRADITIONAL MODULES ...
Page 85: ...6 6 OVERVIEW DEFINITY GENERIC 2 WITH UNIVERSAL MODULES ...
Page 119: ...7 34 MDF lDF DESIGN DEFINITY GENERIC 2 WITH UNIVERSAL MODULES ...
Page 123: ...8 4 ELECTRICAL PROTECTION DEFINlTY GENERIC 2 WITH UNIVERSAL MODULES ...
Page 135: ...10 8 INSTALLATION EXAMPLE DEFINITY GENERIC 2 WITH UNIVERSAL MODULES ...
Page 139: ...11 4 BRI DEFINITY GENERIC 2 WITH UNIVERSAL MODULES ...
Page 174: ...GL 12 GLOSSARY ...