Higher-Voltage Direct Current Voltage Study, ICT Equipment perspective

Suitable Input Voltage Range for Higher Voltage Direct Current System was studied from the point of view of Information Technology and Communication Equipments. AC-Power Supply Units in current ICTE products were surveyed and measured. It was found that the limiting factor of the maximum input voltage is the Bulk Capacitors, their voltage ratings were 400V, 420V and 450V, their operating bulk voltages were from 350V to 405V. The lower limit of was 180V. 200V to 340V was derived to be the suitable input voltage range for ICTE that makes most use of the AC-PSU technology. When higher input voltage is planned, re-design is necessary. The major technical challenges are; larger capacitor size when the voltage rating is increased, larger clearance, creepage distance and test voltage required by safety. These are not fatal but require development time and cost. Input connector for HVDC PSU is in development and seems to be promising. Earthing connection that accept multiple Earthing method is possible. PFC circuit removal is not considered possible at this time and need further study. The boundary between two strategies, one making the most use of the AC-PSU technology, the other higher voltage, lies at 350Vmax., and the differences is re-design and hence development cost, time and risk. Total benefit should be considered with point of views from other parts of the system.