The use of variable frequency speed regulation to achieve constant pressure water supply, compared with the use of regulating valves to achieve constant pressure water supply, energy saving effect is very significant (can be calculated according to specific circumstances).
The advantages are:
1. Starting balance, the starting current can be limited to the rated current, thus avoiding the impact on the grid during starting.
2. Since the average speed of the pump is reduced, the service life of pumps and valves can be extended.
3. It can eliminate the water hammer effect during starting and stopping.
Generally speaking, when one motor is controlled by one inverter, it is only necessary to match the capacity of the inverter with the actual motor capacity. When one inverter controls two motors at the same time, in principle, the capacity of the inverter motor should be equal to the sum of the capacities of the two motors. However, if the water consumption at peak load is much different than the full-speed water supply of the two pumps, consider reducing the capacity of the inverter appropriately, but be careful to leave enough capacity.
Although the pump operates at low speeds, the motor's operating current is small. However, when the user's water consumption changes frequently, the motor will be in a frequent rising and falling state, and the current of the rising and falling speed may slightly exceed the rated current of the motor, causing the motor to overheat. Therefore, thermal protection of the motor is required. For such temperature rises accumulated due to frequent rise and fall, the electronic thermal protection function in the inverter is difficult to protect, so thermal relays should be used for thermal protection of the motor.
In terms of main function presets, the highest frequency should be the highest operating frequency of the inverter with the rated frequency of the motor. When using the PID regulator, the rise and fall times should be set as short as possible to avoid affecting the dynamic response process determined by the PID regulator. If the inverter itself has the PID adjustment function, the set speed and deceleration time will be automatically invalidated as long as the PID function is set at the preset time.
