Control and protection automation of circulation pump
Some manufacturers of circulation pumps equip their pumps with control automation as standard or upon request, which is capable of performing the following functions:
- Starting pumps according to a specified time schedule.
- Blocking the pump start when the allowable frequency of starts is exceeded.
- Switching off the pump when the suction pressure drops below the specified value.
- Automatically maintaining the flow rate through the pump, pressure at its outlet or the head created by it.
- Starting the backup pump when the working pump stops or switching between the working and backup pumps according to a time schedule for uniform wear. Starting the backup pump when the working pump stops is mandatory for circulation pumps installed in heating systems.
Protection of circulation pumps can be provided as part of the standard pump block or separately.
The minimum list of pump protections includes:
- Dry run protection - stops the power supply to the pump motor if the suction pressure drops below the minimum pressure required to fill the pump with liquid or for cavitation-free operation.
- Thermal pump protection - stops the power supply to the pump motor when the shaft is blocked or when it is dry running. Thermal protection is often included in the standard configuration of circulation pumps.
- Protection against phase voltage imbalance - stops the power supply to the pump in case of phase voltage imbalance (only required for three-phase pumps).
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District heating substations