Telefonaktiebolaget Lm Ericsson (Publ)

Emerson Energy Systems, Ab

Folke J Ekelund

Leif T Hansson

Roland J Wald

Kjell Rundkvist

Attila Mathe

Per O Lilja

Gote Johansson

Matts F Stahl

A full float system with Transient Free Multiple Load Disconnection Reconnection (TFMLDR) is disclosed. The system is based on a concept of always connecting loads and dedicated rectifiers together, and then connect such groups (1-n) via power switching devices (C -C ) to a pair of busbars. A backup battery is typically connected directly to the busbars via a respective fuse (F 14 F ). The disconnection/reconnection of individual groups to a busbar can then be controlled such that no transients are produced in the system voltage. Such a system is advantageous for reconnection of a load after a disconnection due to a mains power failure. The loads present a substantial input capacitance assisting in stabilizing DC power supply to the load and this load is directly connected to a rectifying unit delivering voltage controlled power during normal mains power operation. After a disconnection of a load from the busbar and the battery by the power switching member, a reconnection will be done in the following order. The rectifier will deliver current controlled power, which then charges the input capacitance of the load up to a voltage level close to the voltage of the battery. Then a reconnection to the battery with limited inrush current will be achieved thereby obtaining a practically transient free reconnection to the battery.

System for power connection and reconnection

A current limiting short-circuiting protector is disclosed which utilizes an electronic and thermal feedback principle for achieving precise and rapid release of the protector, which can be readily reset. The principle utilizes a non-linear powerful temperature-dependent resistor in the collector circuit of a field effect transistor which serves as a current valve and through which the total current to be monitored is passed. The circuit replaces a conventional fuse and may also function as a load on/off control means. When a fault occurs in the load, the erroneous current is limited to a much lower value than is the case with a conventional fuse.

Short circuit limiting protector

Protective circuit for a hacker type DC converter

Growing community of inventors

Norsborg, Sweden

Folke J Ekelund