8937-HN in the automatic mode of operation to start running, first detect the pool water level, if the pool water level meets the set water level requirements, 1 # pump frequency AC contactor suction, motor and frequency converter connection, frequency converter output frequency from 0Hz to start rising, at this time, the pressure transmitter detects pressure signals back to the PLC, by the PLC after the PID algorithm to control the frequency converter output; such as pressure is not enough, then the frequency rises to 50Hz, after a delay of a certain period of time, the 1 # pump switch to frequency, 2 # pump frequency AC contactor suction, frequency converter start 2 # water pump, frequency gradually rise until the water outlet If the pressure is not enough, then the frequency rises to 50Hz, after a certain time delay, the 1 # pump switch to frequency, 2 # pump frequency AC contactor suction, frequency start 2 # water pump, the frequency rises gradually, until the water pressure reaches the set pressure, and so on to increase the pump.

8937-HN water consumption decreases, the water pressure exceeds the set pressure, the PLC controls the frequency converter to reduce the output frequency, reduce the amount of water to stabilise the water pressure. If the frequency converter output frequency is lower than a set value (water pump frequency, generally 25Hz), and the water pressure is still higher than the set pressure value, PLC start timing, if within a certain period of time, the water pressure is reduced to the set pressure, PLC give up the timing, continue to frequency conversion speed operation; if within a certain period of time, the water pressure is still higher than the set pressure, according to the principle of the first cast first stop, PLC will stop the water pumps that are running the most running time. running pumps in the longest running time of the industrial frequency pump, until the water pressure reaches the set value.

8937-HN For residential water supply or other water supply systems with strong water consumption periods, a small flow pump can be set. For example, in the evening at 12:00 to 5:00 a.m., the residents of living water is very little, a 30kW pump in order to maintain the water supply pressure also need to work for a long time in the 25Hz or so, the motor not only to consume more than a dozen kilowatts of electricity, but also to work for a long time in the low-frequency state, which greatly affects the life of the motor. If the system is set up a 5KW or so of small flow pumps, in order to maintain the water pressure, by the small flow pump frequency conversion work, not only the motor works at a higher frequency, but also consumes a small amount of power. In the selection of small flow water pump, its power is generally 1/4 to 1/6 of the power of the main water pump, head and the same as the main pump.