Pulverizer Electrical Problem Solved

Electrical engineering root cause analysis (RCA) related to pulverizer poor availabilities and the problem solved.

Article Type:	Root Cause Analysis (RCA)
Category:	Electrical
Equipment Type:	Bus ducts, Switchgear, Transformers,
Author:	S. Raghava Chari

Note: This root cause analysis (RCA) is from real-time scenarios that happened in industries during the tenure of two or three decades ago. These articles will help you to improve your troubleshooting skills and knowledge.

Pulverizer Problem

Why low on stream hrs? Because of the V-belts coupling the 1500 RPM motor and 750 RPM pulverizer last max a month!

Why? The reasons are: 

1. Because of corrosion and dust frozen Inoperable belt tensioners, the crew crow bar the first belt into first drive and driven pulleys’ grooves and crow bar it to the last grooves, groove by groove. All belts go this way. Thus they are ½ dead right at installation
2. Belts running in the hygroscopic dust deposited pulley grooves slip, squeal to the high heavens and die within a month or often sooner
3. Consequent 750 sets of V-belts and 24 pulleys sets changes reduce pulverizer availabilities to 50%, require frequent pulverizers changeovers etc. and tire the operation and maintenance crew unbearably and reduced production by 10 to 15%

Authors Solution

A few days ponder showed a way out:  the author recalled his college day pole changing motor topic; though he did not understand Motors application Handbook” given winding change details, and electrical engineers were diffident, a smart re-winder rewound a test motor for 750 RKM.

Its tire coupling coupled to a pulverizer did so well that all enthusiastically modified all the pulverizers’ drives within a month.

Benefits of the RCA Solution

The below are the mentioned benefits of the author’s solution.

1. Rs 5, 00, 000 yearly savings from no pulleys and no belt changes
2. No Crew overtime payments 
3. 5% less power consumption i.e. yearly recurring Rs 5, 62, 000 – 1980 costs –  savings 
4. Far higher pulverizers and motors bearing lives
5. Pulverizers and hence plant availability shot by 10%
6. Freedom from boring, repetitive and low-tech tasks boosted technicians and operators morale
7. The operation and maintenance crew freed of dull low tech repeat chores thanked the author and spent the saved time for knowledge improvement
8. Thanks to items 1-5, the modification pays for itself in a day

Author: S. Raghava Chari

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