Overvoltages or undervoltages in systems often have negative effects on the connected equipment and can bring the whole or parts of the system to a standstill. The EES supervision relays are compactly designed and are suitable for mounting in the distribution cabinet. The voltage supervision is carried out separately for every phase, so not only the mean average value of the voltages, but the actual asymmetry and the individual phase failure is being recognized. In addition the neutral conductor is also monitored on break. Limiting values can be adjusted through potentiometers.