2.4 kV 450 kW Motor Current Fluctuation Problem.

• If the contents of the dryer were shaped akin to a paving slab, for example, the current would fluctuate as the slab were driven up the rotating cylinder, flipped over, and tumbled back to the invert of the drum.

Without wanting to start a game of "20 questions", what is the nature of the substance that this motor is trying to rotate?

Do you really think this is necessary? A link would have been superfluous enough...

It seems the load is unbalanced...could be binding in the transmission or coupling arrangement...what is the interval of fluctuation, that should provide the clue...

1. Is the motor running smoothly, without any rough sound, cranking sound, struggling sound?

Mechanical problems in the transmission and coupling arrangement as mentioned by SolarEagle may exist. Others may be faulty bearings, lack of parts lubrication, and mechanical faults on the dryer mechanics.

2. Have you measured the voltage and current on each phase to ensure their balanced?

Unbalanced load as mentioned by SolarEagle.

3. As PWSlack stated, what is the nature of the substance?.

Sometimes production preparation of substances may not be right, high density, that loads motors.

4. Have you shut done the motor and measured it's winding resistance for balance resistances and insulation?

Weak insulation and unbalanced resistance may cause motor to struggle in maintaining load. Motor operating temperature may be high.

5. What is the level of pollution in the environment of the operating motor?

In case pollutant particles have settled into the motor's stator, interfering with rotor operation and magnetic flux production.

6. Are there any other equipment on the same supply line feeding the motor?

Motor may be struggling to hold load due to low voltage caused by other equipments on the same supply line. Or someone has connected something on the same line which is causing the motor to fluctuate upon low volatge.

7. Are the motor contactors good? Check the three phase contacts of the motor contactors, in case arching may have chewed away one of the contacts that they are not making well enough to bridge current through. Check the contactor coils if coil resistance is good, sometimes coils fall weak and contactors fluctuate. Check contactor north and south electromagnet surfaces, in case they are polluted and need cleaning.

8. Check for anything not right in the control circuit of the motor.

Hi Zaheer Khan,

Any feed back from your end....have you solved the problem with your motor?