Power supplies, such as switching power supplies, are used for providing direct current (DC) supply for various electronic devices, such as base stations in a cellular communications system. Such power supplies have certain output current limits, which must not be exceeded. It is common to use circuit breakers in order to protect power supplies from excessive currents due to overloads. The circuit breakers also protect wiring in high energy circuits and limit outages in case of fault conditions. A fault in one unit thus does not cause breakdown of other units of the same power supply.
A common type of a circuit breaker is an electromechanical circuit breaker. Such a circuit breaker has a fixed current limit or fixed tripping curve, and exceeding current limit or tripping curve causes the circuit breaker to trip. A circuit breaker usually has a lever at its front panel for resetting the circuit breaker. Electromechanical circuit breakers are produced in large quantities, and they are standard, reliable and low cost components, which have been approved by authorities.
However, there are some problems related to the electromechanical circuit breakers. After tripping they need to be manually reset. Electrical devices may be installed in remote locations, and it may require much effort and time to travel to such locations. Tripping of a circuit breaker may be caused by reasons which do not require repairing the electrical devices. In such situations it is still necessary to travel to the installation location in order to reset circuit breaker. To solve this problem there are arrangements for resetting a circuit breaker with remote control. Such a solution is disclosed in patent application document U.S. Pat. No. 6,522,227 B1.
Another problem with electromechanical circuit breakers relates to the fixed tripping current limit or fixed tripping curve. There are various situations where the current limit of a circuit breaker needs to be changed. In order to change the current limit the circuit breaker must be changed to a different one. Changing a circuit breaker requires servicing work at the installation location of the electrical device. It is also possible that a circuit breaker with the required current limit is not available. In such case it is necessary to use a circuit breaker with non-optimal, lower current limit. This may cause unnecessary tripping of the circuit breaker.