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TAU-72.IP/TAU-36.IP Universal Network Terminal 191
Rloop = Lloop*Rsp20 = 2*Lcab*Rsp20;
Lloop = Rloop/Rsp20.
In case of phone lines, loop resistance includes phone unit resistance: 600Ω
If the extended range mode is enabled, ('Extended range loop' setting, see Section 5.1.2.1), equipment
manufactured by Eltex provides maximum loop resistance of 2100Ω. Subsequently, loop resistance excluding the
phone unit equals to 1500Ω. Thus, maximum loop length is calculated by the equation:
Lloop = 1500/Rsp20 [km].
4.
Line length is calculated by the equation:
Lline = Lcab = Lloop/2 = 1500/(2*Rsp20) = 750/Rsp20 [km].
5.
If you have to consider the cable temperature, the cable line length will be calculated with an
adjustment:
Lline = 750/(Rsp20*(1-a*(T-20)))
where
a—is a temperature factor (table value)
T—cable temperature