Adjustment of variable-frequency pumps
Thread Content
Many devices now are equipped with variable-frequency pumps. How is stable operation maintained when the variable-frequency pump is switched to a non-variable-frequency backup pump, and how can the variable-frequency pump be brought back to its most energy-efficient state as quickly as possible upon switching back?
When switching from a variable-frequency pump to a non-variable-frequency pump, it is necessary to first start the non-variable-frequency pump, then slowly open the outlet valve. The operator inside the control room adjusts the speed of the variable-frequency pump; once the speed reaches a certain level (as specified generally), the manual valve at the outlet of the non-variable-frequency pump is fully opened, and then the control valve is used to regulate the flow. Switching from a non-frequency-variable pump to a frequency-variable pump is even simpler: the operator inside adjusts the speed of the frequency-variable pump, while the operator outside slowly closes the manual valve of the non-frequency-variable pump; once a certain amount has been achieved, the non-frequency-variable pump can be turned off. The whole process is very simple.
The so-called most energy-efficient state means using exactly the amount of power needed, and the speed of the motor can be adjusted through variable frequency control.
The electrical control cabinet of the pump can be designed for automatic control, enabling automatic switching as well as automatic adjustment of flow rate and output pressure
Is it a switch between variable-frequency pumps? Personal suggestion: 1. Before switching pumps, check the process parameters related to the pump that will be used (the pump that is to be started). 2. Use the walkie-talkie to contact the control room, start the pump, increase the setting of the frequency converter inside the room (raise the value), and slowly open the pump’s outlet. The personnel inside adjust the frequency converter of the originally operating pump according to the actual flow rate. 3. When the opening degree of the frequency converter of the originally operating pump reaches a point where it can no longer increase flow rate, adjust the frequency of the starting pump to an appropriate value. 4. Close the outlet valve of the pump that is currently in operation, shut down the pump, and check the process flow.
You want to achieve constant pressure control, right? If the pressure is low, use one unit; if that’s not enough, start another one? Do we still need two units for timed switching? There is a ready-made frequency converter available; it’s very intelligent, with automatic switching, scheduled rotation, pressure control, and more. I’m not able to send the details yet – please email me at nb_zhonglin@163.com
Are there any operating procedures for variable-frequency pumps upstairs and downstairs? To put it more specifically: when starting up, what frequency is reached? And if the variable-frequency pump is equipped with a stroke mechanism, what should be the initial value of that stroke? How does the frequency change when the pump is stopped?