Variable-frequency centrifugal pump
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May I ask, for variable-frequency centrifugal pumps, can the outlet valve be kept fully open while using variable frequency control? Also, does setting the frequency conversion to 100 make it the same as when the pump is operating at its normal frequency? I need the teacher’s help to solve this. . .
The opening degree of the outlet valve should be adjusted using the power frequency, after which variable frequency control should be applied.
Thank you. If the frequency is set to 100, it’s the mains frequency, right?
First, what do you need to control? Control traffic? I feel a bit dizzy. Also, in China the frequency is 50HZ – how can it be adjusted to 100? Setting it to 50 gives the standard power frequency; I’ve heard though that some devices can be set to 60HZ, but I’m not sure if that’s true
For frequency conversion, we use a percentage of the rotational speed, and 100% can be used.
Full export opening is controlled by frequency conversion; at 50HZ, it operates in the same way as at the power frequency.
When the frequency converter displays 100%, it means 50Hz. The maximum setting for frequency converters of domestic manufacture is generally 60Hz; however, operating above this limit may affect the motor’s lifespan, mainly due to excessive speed of the bearings and poor cooling by the fans. For control purposes, the outlet valve should be fully opened, and if there are control valves as well, they too need to be fully open. The frequency converter can be used to set up a circuit in the DCS for automatic control
It is necessary to first understand what the purpose of starting with the outlet closed is. This is actually quite simple: many devices need to be started under low load or no load, with the load being increased only after normal operation is achieved. The same applies to pumps – when starting, the load must be reduced to a minimum level, mainly to prevent excessive load at the moment of startup, which could damage the equipment and the motor.
The purpose of increasing the frequency conversion is to keep the outlet valve fully open and reduce local resistance. Additionally, a variable-frequency output of 100 is essentially the line frequency~~
When a variable-frequency pump is controlled via frequency variation, the outlet valve must be fully opened, and the speed is regulated by the level of current in order to control the flow rate.
This 100 should be the percentage of opening, meaning fully open.