DC control battery system protection and coordination
Battery system failure jeopardizes a power system by eliminating the DC control power source for AC system circuit breakers and protective devices. The protection of control battery system components including the battery, battery charger and individual circuits is reviewed. Optimum battery system protective device coordination is discussed.<<ETX>>
Maintaining 'maintenance-free' batteries
The maintenance of valve-regulated sealed lead-acid stationary batteries is described, and comparisons are made with traditional vented lead-acid battery maintenance practices. The operation of the valve-regulated sealed lead-acid battery is also discussed. Two designs are currently available, both of which operate on the oxygen recombinant cycle. This cycle effectively eliminates evolution of free hydrogen gas under normal operating conditions. Maintenance considerations for valve-regulated sealed lead-acid cells are similar to those for flooded cells. It is noted that the terms 'sealed' and 'maintenance-free' commonly associated with these cells are misnomers, and it is urged that the use of such terms should be discontinued.<<ETX>>
Frequency selective surface design for blinds applications
In this paper, the reconfigurable blind structure with frequency selective surfaces(FSS) for the building applications are presented. Frequency transmission characteristics for different angles of the proposed blind-FSSs are investigated and verified through simulation and measurement. The simulation results show that we can implement the reconfigurable blind-FSS for multiband wireless applications. To verify the proposed paper, two kinds of blind-FSSs, crossed dipole FSS and circular ring FSS are fabricated and measurements are performed for different angles. The proposed structure in this paper which is very simple, can be easily applied to any planar surface for wireless security applications at low cost.