The original high-level water tank type water supply can be easily modified by frequency conversion. When the water level in the high-level water tank reaches the upper limit, the water inlet of the water tank is closed by the float valve, and the system is automatically adjusted by the frequency conversion. When the flow rate is small, the pump automatically sleeps, and the water tank is turned to The system provides water supply. When the water tank level drops to a certain value, the water pump automatically wakes up. For systems with small water supply, the water inlet of the original high-level water tank can also be closed, and the water pump is controlled by the frequency conversion to meet the water requirements. November 2002 The constant pressure water supply system customized for the famous city of Shanghai uses LG inverters, PLCs, pressure sensors, etc. to form the control system. Operation mode: The system has two operation modes: manual and automatic:
⑴. Manual operation
    Press the button to start or stop the water pump, and the start and stop of 1#-4# pump can be controlled separately according to needs. This method is mainly used for maintenance and inverter failure.
⑵. Automatic operation
    After closing the automatic switch, the 1# pump motor is energized, and the output frequency of the inverter rises from 0Hz. At the same time, the PID regulator receives the standard signal from the pressure sensor, compares it with the given pressure parameter through calculation, and sends the adjustment parameter to the inverter. If the pressure is not enough, the frequency will rise to 50Hz, the 1# pump will switch from frequency conversion to power frequency, start 2# frequency conversion, the frequency converter will gradually increase the frequency to the given value, add the pump and so on; if the water consumption decreases, start first The pump starts to decrease, and at the same time, the system runs smoothly according to the adjustment parameters given by the PID regulator. If there is an instantaneous power failure, the system will stop; after the power returns to normal, the system will automatically resume operation, and then start the 1# pump frequency conversion according to the automatic operation mode until it runs stably at the given water pressure value.
    The frequency conversion automatic function is the most basic function of the system. The system automatically completes the entire operation process of soft starting, stopping, and cyclic frequency conversion of multiple pumps.
error alarm:
    When there is a lack of phase, inverter failure, lower limit of liquid level, overpressure, differential pressure, etc., the system can send out an audible alarm signal; especially when there is a lack of phase, inverter failure, lower limit of liquid level, or overpressure, the system It will also automatically shut down and send out an audible alarm signal to notify the maintenance personnel to come for repairs. In addition, when the inverter fails, the system will automatically stop. At this time, it can be switched to manual mode to ensure uninterrupted water supply to the system.
Pump overhaul
In order to maintain and repair the water pump, it is required to stop a certain water pump within a period of time under the normal water supply state of the system. The system is equipped with a forced backup function of the water pump (hardware backup), and a certain water pump can be backed up at will without affecting The system runs normally; in order to make the water pump take turns, the system also has a software backup function (clock control function, realized by the time controller), the working pump and the backup N pump have the periodic timing switching function, and the periodic interval is set by the time controller: It can be adjusted continuously every time between 1 hour and 96 hours.