Problems with the motor
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A 11KW motor in the factory was damaged; its rotation speed was 1460 r/min. A new 11KW motor was installed, but it was of a different model, and its rotation speed was 2940 r/min. But it shuts down not long after starting up. Why is that? Does anyone know?
This post was last edited by Albertlu on 2011-8-13 at 22:25. The torque is different; higher speeds result in lower torque. The speed will gradually decrease, the current will increase, and eventually the current protection will be activated, causing the motor to stop.
Amazing! It can be replaced even when the rotation speed is half different – what kind of amazing device is this?
The torque formula is T = (60/2π) * (P/N). The higher the speed, the lower the torque. In your case, the torque needs to be halved; as a result, the current will remain high after startup, which will certainly cause a tripping
The rotation speed was 1460 r/min; it was changed to 2940 r/min. It’s not clear what the load is; usually, a simple replacement isn’t sufficient. In the case of centrifugal pumps and fans, the shaft power of the pump is proportional to the cube of its rotational speed. If the speed is increased to twice its original value, the power increases by a factor of 8.
I give up on you – the original model uses a four-pole motor, yet you buy a two-pole one. It’s strange if there are no problems. Do you have an electrician over there? This problem is really too much. . . . . . When buying a motor, you can’t just look at the power.
You can’t rely on the motor’s power rating; as the speed increases, the actual load power of the equipment driven by the motor rises by 6 to 8 times. In other words, an 11KW motor would be used to drive a load device with a power requirement of around 80KW – that’s far too much; such a motor simply cannot handle it and would always be in a state of overloading. It’s amazing if the thermal relay or motor protection mechanisms don’t trigger in such a situation
When replacing the motor, you should at least buy one that matches the original specifications on the nameplate··
When replacing the motor, you should at least buy one that matches the original specifications on the nameplate··
The thermal relay will activate; your method of replacement is very dangerous.