It is time to reduce motor running loss to optimise textile parameters, says Ashok S.

Industry managers often presume that they have reduced motor running losses through preventive time-based maintenance schedules. Condition-monitoring the motor has shown us daily that we lose energy through trivial aspects in motors and loads.

The input-output ratio i.e. efficiency of each sub-system in the motor multiplies for overall efficiency to drop appreciably. Compared to drop in efficiency in the load over years, the drop in efficiency in motor is less, but the same can be focused now to reduce the cup-to-lip losses from the motor input to the output load.

Existing textile spinning mill ring frame motor working

Motors running with the following parameters face reduced efficiency. They are:-

1.       Motor loading is at the inefficient 50 per cent loading. The same can be revisited to change loading pattern.

2.      Motor is now retrofitted with VFD and the new motor can be sized less to avoid under-loading.

3.      Motor is not able to ventilate as it is totally enclosed and gets heated up by surrounding pneumafill air.

4.      Motor needs periodic lubrication with poly urea thickened specialty grease and needs extended re-greasing interval.

5.      Losses in power transmission are more now from motor through belts, pulleys, tin roller bearings, tapes upto the spindles.

Is motor loading band efficient?

Take the case of 1200 spindle long frame, the existing motor is 55 KW rated and the loading is around 40 to 50 per cent inefficient average loading only. We presume that the motor is now in the threshold start of efficient loading zone, but it is not so. The motor loading is the first and foremost factor to improve its running efficiency.

 

1.jpg

Any motor run at slightly less than half loading capacity is losing efficiency due to the droop characteristic in the inverted flat bell shape in the Loading Vs Efficiency curve for the old IE 1, IE 2 motors. The universal rule is, when the motor uses less than half the loading capacity, it is prone to efficiency drop. The flat efficiency band is broader in IE 3 and IE 4 motors and slope is elongated, gradual and not steep, compared to the decade-old IE 1 rated motors. But as a motor user, we must first monitor the motor so that the same motor is always loaded above 60 per cent to obtain optimum efficiency.