Electromotive tap is used in the system for central supplement of the lubricating pumps. When the level of grease in a specific lubricating pump drops to minimum, electrical cabinets gives the command to open the taps and includes a central pump to supplement. When grease reaches the maximum level, the tap is closed and the supplement pump switches off. In this way it is secured that the grease is safely transported and prevented from reaching the contamination by impurities. This is particularly suitable for places where working conditions are difficult and environments are dirty, such as steel mills, coke plants, foundries, cement plants. . . Due to its robust construction and ease of management with the whole system, this device is very suitable for use in all systems for central grease supplement.