A constant water supply is realized using a computer-controlled pump that runs at a fixed frequency. This pump is equipped with valves and pressure control. The return pump, which is connected to the Presscon ELC System, is started and operated by means of a frequency converter. The rotation speed of the return pump is determined by the ELC System. Since the return pump is frequency controlled, it can run faster or slower than the water supply pump. As a result, the amount of water in each tank is precisely regulated. The ELC System can also determine the water flow direction with the help of valves.

For example:
If the pressure of the water column in the control tank is 15 mbar lower than that in the reference tank, the analogue output generates a signal of 4 mA. This results in a slower operation of the return pump.
If the pressure of the water column in the control tank is 20 mbar higher than that in the reference tank, the analog output generates a signal of 20 mA. This leads to a maximum rotation speed of the return pump of 50 Hz.
The system regulates solely on the basis of pressure differences and not on the basis of water level. Therefore, it may happen that the water level in tank X is higher than in tank Y. The greater the temperature difference between tank X and Y, the greater the difference in level will be. Therefore, the water level in tank X may be higher than in tank Y. The greater the temperature difference between tank X and Y, the greater the level difference will be.

1. Starting from two pumps with the same capacity and speeds.
2. Is this not possible and the level differs too much? Then you can no longer control the level.
3. The control tank is the tank where the return pump pumps the water back in.