User's Manual

Installation and Safety Guide
47
Connection to ISDN network
Ports for the connection of other apparatus
The following interfaces normally operate at SELV (Safe Extra Low Voltage)
levels:
■ Asynchronous (console) ports
■ Ethernet ports
■ G703 ports
■ Synchronous ports
Note SELV is a secondary circuit whose voltages do not exceed a safe value
under normal operating conditions and under single fault conditions. Under
normal operating conditions the voltages do not exceed 42.4
V peak AC or
60 V DC.
TNV1
The following interfaces are Telecommunications Network Voltage (TNV1)
circuits, which operate normally within the limits of SELV:
■ BRI ports for connection to ISDN Basic Rate telecommunications networks
■ PRI ports for connection to ISDN Primary Rate telecommunications
networks
■ E1/T1 ports for connection to E1/T1 services
Note A TNV1 circuit is a circuit which under normal operating conditions does
not exceed the limits for SELV and on which overvoltages from
telecommunication networks are possible.