A hybrid integrated trunk and subscriber line interface
A two-chip hybrid integrated trunk and subscriber line interface has been fabricated for voice and data applications. This paper will discuss features including a programmable battery feed with lightning protection, battery-reversal signaling, 2-4 wire conversion, loop closure detection and power down capability.
A 90V switching regulator and lightning protector chip set
A switching regulator providing variable voltage to accommodate loop resistances from 0 to 2800 Ω with 1.5W power limit has been developed. A transformerless trunk and subscriber line interface which serves as a protection device to shunt 10A lightning pulses to ground will be described.
Transient nonlinear thermal stability analysis of metro cable under pulse power
The load of metro cable system varies a lot from morning rush hours to the evening closure time. With many trains hopping in the rush hours, the long term and economical short term thermal stability become a big issue as a result of the large difference between thermal time constant and the electrical time constant of cable. Based on a 10kV three-core XLPE metro power cable model, the theoretical thermal capacity was calculated according IEC standard. Then, a Finite Element Method (FEM) was employed to analyze the transient electro-thermal phenomena, taking into account various types of power loss in cable system and the non-linear electrical conductivity of the conductor. Finally, the thermal distribution inside the cable was presented as a function of time, and the maximum thermal capacity was predicted in metro cable.