DIRECT VOLTAGE BACK-UP SYSTEM AT A POWER SUPPLY OUTLET

摘要

The invention concerns a back-up system which comprises a control unit (CU) and at least one back-up battery (BATT), in particular an accumulator which can be charged via the power supply (SV). The control unit (CU) connects the back-up battery when the actual value of the direct voltage (Ua) is less than a predetermined minimum value (Uamin), generates a predetermined back-up interval (tm) and disconnects the back-up battery cyclically when this interval has elapsed. The advantage of the system according to the invention is that restoration of the output direct voltage of the power supply can be effectively and simply detected. Since the power supply output direct voltage which is essential for the consumers is monitored, the consumers continue to be supplied with power both when the supplying input voltage fails and when the power supply fails. The device can be added on downstream of a power supply without requiring modifications to the construction thereof. A further advantage of the device is that it automatically connects the battery for back-up purposes as soon as the load voltage falls below the minimum value, even when the power supply output direct voltage fails as a result of short-circuiting. The invention thus enables the output direct voltage to be taken over or backed up almost continuously in the case of a large number of disturbances.