The devices are designed as an enclosed cabinet which contains the following:
- frequency converters;
- switching low-voltage equipment;
- input/output and interface units;
- alarm and display elements.
Cabinets are designed for mounting on a horizontal surface or a vertical wall.
The devices may contain a different number of switching units, controls, alarm and display elements, depending on the circuit solutions (on demand). The number and size of cabinets depends on the set
of elements in the device.
The devices support the following:
- pump group alternate soft start with successive switching to mains;
- connection of any or only one pump drive motor to the frequency converter and the frequency control of its speed to maintain a preset process variable in the automated control system;
- periodic change of working and standby pump units, their operation mode change and control according to a preset algorithm;
- connection of any not connected to a frequency converter pump drive motors to mains;
- operative selection of the pump drive motor when switching from one pump to another;
- pump drive motors overload and short circuit protection;
- energy efficiency.
The device provides a savings of 30% to 90% of electricity depending on the regulation range.
The device makes it possible to reduce the wear of electrical equipment, pumps, lock valves and pipelines, 1.5 to 2 times increases service life and overhaul life of equipment.
Functional diagram of the pump unit is given in Figure 1.