ICQCC 2011 Yokohama Prevention of undesired tripping of HT
Contents
1. i 10 46 6 2 U V UPS i ite 7a OK LEB FSCO HT gt S ALE MEE LC DHEDEF APO EIA T HT D2 BALPEAARVTHES 220 2010 FET 570 J VL ERMA2. T 61 A B C A 36 OF PDCA 12 Tron amp Steel Tarkera Pump House and Rolling Mill area HT 65 2 NSPCL TIslanded Unit MVA WESCO 256 0 9 K FHETT SEARE oZ
3. besides enhancement of analytical ability amp team spirit For recurrence prevention an operation manual along with DOs DON Ts for motor breakers was made and kept in all the sub stations ICQCC2011 Yokohama 9 11 9 14 2011 ICQCC 2011 Yokohama HT VIDYUT CIRCLE P K Biswal Group Leader Senior Technician T N Mishra Dy Leader Senior Technician P K Biswal Member Technician S K Nayak Member Senior Technician D D Jena Member Senior Technician Maintenance Section of Power Distribution Dept Mr R K Shah AGM Circle Facilitator Rourkela Steel Plant Steel Authority of India Limited INDIA ALE AMX CPP 1 NSPCL WESCO Utility 6 6kv 33kv I SS 2 33 KV VCB 450 ROES AVV SA TEWE 6 6kV pe ee iC AB BIE KY VEZZI ZL R pau
4. CE FRAMED KD T2 E Stream F 21
5. ICQCC2011 Yokohama 9 11 9 14 2011 Stream F 21 ICQCC 2011 Yokohama Prevention of undesired tripping of H T Motor Drives Name of QC VIDYUT CIRCLE Name of Presenters P K Biswal Group Leader Senior Technician T N Mishra Dy Leader Senior Technician P K Biswal Member Technician S K Nayak Member Senior Technician D D Jena Member Senior Technician All are the workmen working in Maintenance Section of Power Distribution Deptt amp are members of QCFI Secunderabad India Mr R K Shah AGM is the circle Facilitator Company Rourkela Steel Plant Steel Authority of India Limited Country INDIA ABSTRACT Power Distribution Department is responsible for receiving power from CPP 1 NSPCL and WESCO Utility grid at different voltage levels and distributing them as required All the circuit breakers provided originally were of 6 6kv 33kv voltage level Siemens Expansin type Gradually department has replaced the 33 KV circuit breakers with Siemens VCB but till now 450 numbers old expansin type breakers still exist at 6 6kv voltage level Out of which 59 numbers are of R trip type commonly known as No volt tripping types which are used for motor feeders whereas others are of F trip type which are generally used for transformer and line feeders 61 problems were identified and categorized into A B amp C Present case study was selected through Rating method out of 36 Category A problems 12 steps of problem solving me
6. thodology was followed using PDCA cycle Motor drives of Iron amp Steel Tarkera Pump House and Rolling Mill area are having Siemens Make HT breakers 65 nos Breaker design demands No Volt Trip coil to be powered before closing of the Breaker Each tripping takes 2 hrs to restore the production Further breaker tripping in NSPCL units power generating company cause loss of load for Islanded Unit for which we pay high energy bill to WESCO for extra drawal of Power once it crosses the specified MVA In hot mills alone cost of per tripping was USD 236000 as production loss Objective was to provide uninterrupted power supply to all these units Circle using various Simple Quality Control Tools like Brainstorming Ishikawa Diagram Data collection Stratification amp Why Why technique analyzed the problem and evaluated the causes voltage dip in the system contributing 46 alone was accepted as root cause out of the ten main causes Through brainstorming six alternate solutions developed were evaluated and finally accepted the solution providing UPS power with U V relay with time delay of up to 2 seconds to take care of its root cause A prototype was made tested and finally implemented accordingly after OK result After this voltage dip did take place but all HT motor breakers worked OK without any interruption Resultantly production loss due to breaker tripping of HT motor drives has been NIL saving 5 7 million USD in 2010
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