Pump current exceeds the rated value
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Our company has a pump of the model PAC25-315, equipped with a motor whose power is 22 KW. The medium handled by this pump is water, and its flow rate is 12 m3/h. During operation, it was observed that the current drawn by the motor exceeded the rated value, at 43 A, which is higher than 41 A. Upon inspection: 1) When the motor was disconnected from the coupling and tested without load, the current was 16.1 A. 2) When the outlet valve of the pump was not opened, the motor current was 40 A. 3) After disassembling the pump head, no foreign objects were found in the impeller rings or flow channels, and the gaps were within the standard range. 4. The barring is normal. 5. When the outlet flow rate is increased to 2 m3/h, the current rises to 43 A. What could be the reason?
It is inferred that there was an error in the initial design, which led to a mismatch between the motor power and the power required by the pump shaft; as a result, the motor chosen was too small. Pumps with a low specific speed are prone to very low efficiency due to excessive mechanical losses. This is likely a problem on the part of the manufacturer, and it would be best to have actual factory test reports to verify this.
Whose pump is it? With parameters of 25-315, it should be a straight-vane pump. This type of pump has low efficiency; check the impeller diameter – if it’s over 285 mm, then a 22 kW motor is definitely too small for it