Reasons for the centrifugal pump to trip due to overcurrent
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Experts, I am facing a difficult problem at work: there are three waste sodium hydroxide wastewater pumps in the acetylene purification section. The model of these pumps is IS200-150-400; their rated flow rate is 400 cubic meters, the head is 45 meters. They feature mechanical seals, and the motors have a power of 90 KW with a rotation speed of 1450 revolutions per minute. The medium is sodium hypochlorite wastewater, containing dissolved acetylene. The outlet pipe is DN300, while the inlet pipe is DN400. When the pump is operating, the outlet valve cannot be opened fully – it can only be opened to 15% of its capacity. The pressure gauge at the pump’s outlet shows a value of 6 kilograms, though this value is unstable; it can reach up to 8 kilograms at times. The current consumption is 135 A. If the outlet valve is opened further, the current increases, leading to overload and eventually tripping of the pump. The medium entering the pump comes from the cooling tower. The cooling tower is 18 meters tall, with a liquid level of around 10 meters; the gas pressure inside the tower is 5 kPa. The wastewater exits the bottom of the tower and enters a horizontal wastewater tank with a diameter of 2.2 meters, where the liquid level is maintained at 80%. From there, the wastewater flows into the pump inlet. First of all, the pump itself is not faulty.
Try turning the pump to see if there is sticking or abrasion causing increased resistance； Has the medium density increased? ； Check if the motor is faulty
There’s no problem at all; my three pumps have been operating in this manner since they were put into use in July 2016, and the same is true for pump switching. I have been working for almost thirty years and have encountered this situation before. The cranking is smooth with no jamming.
Replace with a larger motor. Solve the problem completely. That’s how we solve problems.
Based on the available data, a rough calculation can be done to determine the power of the motor that should be used. This problem can be addressed in two ways: by using a larger motor, or by modifying the impeller. Here is a formula for calculating motor power; it seems that images cannot be transmitted. http://www.docin.com/p-230560183.html
How high is the liquid surface from the ground? What is the specific gravity of the medium?
Has the pipeline loss in the export line been calculated? Are the two units working properly?
The wastewater tank is located about 3 meters above the ground, with the liquid level being at a height of just over 2 meters above the ground. The pump outlet returns to a height of 15 meters in the cooling tower
Export pipeline losses are not taken into account; normally, one unit is in use while two are in standby, and the situation remains the same regardless of which unit is used
As a rough estimate, either the power used by your motor is too low, or the impeller is too large; as a result, the head at a rated flow rate of 400 cubic meters is high. You can take a look at the flow-rate vs. power curve and the head vs. power curve