Hardware Description and Reference for Avaya ... - Avaya Support

Appendix A: Specifications for DEFINITY media gateways
SCC1 fan unit
Four constant-speed fans at the top rear of the cabinet receive -48 VDC from the backplane. An
air filter is located below the fan unit. Air flows down through the filter over the circuit packs. The
filter is removable and can be cleaned or replaced when necessary.
If the cabinet temperature reaches 158 oF (70 oC), the temperature sensor in the power supply
causes the system to shut down. The temperature sensor also invokes the Emergency
Transfer.
System protection
The following types of system protection are provided to keep the switch active and online:
● Over voltage
● Sneak current
● Lightning
● Earthquake
Protection from hazardous voltages
Protection from hazardous voltages and currents is required for all off-premises trunks, lines,
and terminal installations. Both sneak current protection and over-voltage protection from
lightning, power induction, and so on, are required.
Overvoltage protection
The following devices protect the system from over voltages:
● Analog trunks use the 507B Sneak Protector. The local telephone company usually
provides over voltage protection.
● Analog voice and 2-wire DCP terminals can use one of the following types of combined
protection against over voltage and sneak current. The terminals can also use the
equivalent of one of the following types:
- Carbon block with heat coil for UL code 4B1C
- Gas tube with heat coil for UL code 4B1E-W
- Solid state with heat coil for UL code 4C1S
● DCP and ISDN-BRI terminals use the solid state 4C3S-75 with heat coil protector, or
equivalent.
● DS1, E1, and T1 circuits require isolation from exposed facilities. A CSU (T1), lightwave
integration unit (E1), or other equipment provides this isolation.
418 Hardware Description and Reference for Avaya Communication Manager