Shortening the Time of High-voltage Circuit Breaker ...



Shortening the Time of High-voltage Circuit Breaker Preventive Test

of 110 kV and Above

Chen Yifeng QC group

Jiangmen Xinhui Power Supply Bureau, Guangdong Power Grid Company, China

PREFACE

Xinhui Power Bureau is a medium-sized state-owned power supply enterprise which subordinates to Guangdong Power Grid. Up to the early of 2008, it had 28 substations, including four 220 KV substations, twenty-four 110 KV ones. And the high-voltage circuit breaker is the one of the most important electrical equipments which controls the power supply . Therefor , we must test it every year, and we want to complete the test in a shorter time. We found some methods which can reduce the testing time as well as the danger of job by doing a great deal of research, at the same time , to improve the whole working efficiency.

I. Group Profile

High-voltage test unit of Xinhui Power Bureau is responsible for all the test of substations’ high-voltage equipment. There were twelve members in our QC group , all of them are good at doing the testing job. And our QC group is devoted to improving the work efficiency and guaranteeing the quality.

|Group name |Chen Yifeng QC group |Group type |Scene type |

|Gour | | | |

|Task name |Shortening the Time of High-voltage Circuit Breaker Preventive Test of 110 kV and Above |

|Activity number | 11 times |Registration Date |Sep. 21st, 2007 |

|Activity date |2007.07.21 -2008.02.29 |Registration number |NO： 07A-02 |

|Name |Gender |Age |Level |Title |TQC education|Working Distribution in the group |

| | | | | |time （h） | |

|Chen Zihui |Male |32 |Undergraduate course |Monitor |108 |Organizer |

|Yu Zhiwei |Male |26 |Undergraduate course |Vice Monitor |90 |Trimmer |

|Liang Jianxin |Male |41 |Technical secondary school |Member |80 |Executant |

|Wan Liju |Male |44 |Technical secondary school |Member |88 |Examiner |

|Deng Zhiqiang |Male |33 |Technical secondary school |Member |86 |Executant |

|Zhu Yaohui |Male |26 |Junior college |Member |90 |Examiner |

|Lin Meilian |Female |43 |Technical secondary school |Member |90 |Executant |

|Sun Xiuzhen |Female |49 |Senior high school |Member |80 |Executant |

|Li Xianming |Female |34 |Junior college |Member |80 |Executant |

|Zhang Yuetian |Male |24 |Technical secondary school |Member |80 |Executant |

|Tang Minghua |Male |25 |Undergraduate course |Member |80 |Examiner |

Table 1 Registration form of group members

Lister：Yu Zhiwei Sheeting date：2008.02.28

II. The reason of Selection of Title

In order to ensure the normal power supply , we must do high-voltage equipments preventive test every year.

|Time shaft | |

|Work grouping |30-50min |60min-85min |30-40min |40-55min |/ | |

|High voltage test|Waiting |4 persons test |3 persons test |4 persons test PT | | |

|group | |Breaker |CT | | | |

Fig I Argumentation chart of selection of title

Mapper: Yu Zhiwei Listing date: 2008.02.28

III. Mastering Actuality:

1. In the testing period of 2007 , our QC group took sample tests in some of the high voltage circuit breaker in 28 substation , and got statistic as below:

Table 2 Statistic questionnaire of time of high voltage circuit breaker of every substation

|Item No. |Rank of breaker voltage |Statistic number |Average consumption time of the test（min） |Test date |

|1 |220kV |4 |112 |2006.11-12 |

|2 |110kV |25 |84 |2006.10-2007.06 |

|3 |35kV |1 |22 |2007.01 |

|4 |10kV |32 |18 |2006.12-2007.05 |

Lister: Yu Zhiwei Listing date: 2008.02.28

2. QC group found the consumption of the test of high voltage circuit breaker of rank voltage 110 kV and above is the longest according to the statistic , but our bureau is mainly to test rank voltage 110 kV, therefore the testing time of 110 kV high voltage circuit breaker is analyzed mainly here.

The member of our QC group took a simple working flow for a latest test of high voltage circuit breaker firstly so that it is convenient to evaluate a whole flow for every part of the test:

[pic]

Fig 2 Test working flow

Mapper: Yu Zhiwei Listing date: 2008.02.28

According to the order of test flow chart, we got the consumption time of every test and make the statistics of 25 tests as following: (the time of changing equipments for next test has been computerized in the testing time)

Table 3 Statistics of every consumption time

|Item No. |Item name of test |Total time length（min） |Average time length （min） |Add up（%） |

|1 |The time of preparing before test |153 |6.12 |07.25% |

|2 |The time of test of operation voltage of |184.5 |7.38 |15.98% |

| |close/open coil | | | |

|3 |The time of test of contact resistance |1512.5 |60.5 |87.62% |

|4 |The time of test of SF6 |183 |7.32 |96.28% |

|5 |The time of recovering after test |78.5 |3.14 |100% |

|Total time length |2111.5(min) |Average time length |84.46(min) |

Lister: Yu Zhiwei Listing date: 2008.02.28

Diagram of every consumption time had been made as statistics above

Time length=84.46(min) Add up percentage (%)

[pic]

Fig 3 Diagram of every consumption time of high-voltage circuit breaker

Mapper: Yu Zhiwei Mapping date: 2008.02.28

We can see from the chart above: “The testing time of contact resistance of breaker” occupies 71.63% of the whole time of breaker test, and the time would be consumed longer while we carried out the 220 kV breaker contact resistance test . Therefore we had known clearly that we must reduce the testing time of contact resistance of breaker, it was the main link to shorten the time of breaker test.

IV. The Objective

The goal of QC activity for this time is that the average testing time of high voltage breaker can be reduced from 84.46(min) to 52(min) after this QC activity.

The consumption of testing time:

Before QC activity Activity goal

Fig 4 Goal sketch map of QC activity

Mapper: Yu Zhiwei Mapping date: 2008.02.28

V. Feasible Analysis:

Whole analysis:

1. Sometimes , we have spent the average time of 52(min) in doing the breaker test, and the fastest one was 44(min) by using scaffold or other platform which has been built and can be easy to do test at scene in the rebuilding project.

2. As we know, the time which be consumed in similar test conditions by the other test unit usually is within 52(min) , and the manufacturer has the advantages such as convenient position and advanced test platform, the time even can be reduced to 40 (min).

Details analysis:

1.It didn’t take much time in test operation at all, but

more time is spent in the process of test.

2.We can see from the actual data which is

investigated , the main time wasting part

is the contact resistance test.

In the whole breaker test process, it occupied

about 71.63% of the time, we estimated that the time could

be reduced by more than 10(min)

If the time used in climbing up and down during test Chart 5 Analysis chart

could be reduced more than 25(min) , Mapper : Yu Zhiwei Listing date: 2008.02.28

we would achieve our goal.

We had found the key to attain the goal!

All of this just show that the goal is achievable and feasible , our QC group can achieve the goal absolutely by our

effort.

[pic]

VI. Reason Analysis

Why did the test of contact resistance of breaker took so much time , we took part in many activities in a month in order to find out the answer . Through the survey, statistics and brainstorming, the QC group analyzed the main factors, and concluded the result to 4 aspects such as “person”, “machine”, “method” and “Environment”(There is nothing related to the factor “material” in our test, so we have not list it), which can be shown as follows:

[pic]

Mapper: Yu Zhiwei Mapping date: 2008.02.28

VII. Reasoning on The Main Causes

Which one is the main cause, all members were earnest to study, argue one after another , as indicated in the following table.

Table 4 Argumentation of key factors

|Item No.|Factors |Argumentation Descriptions |Checker |Checking Date |Main Cause |

|2 |Manpower is not |Through all the test,we seldom failed the job to the lack of testing workers . |Deng Zhiqiang|2007.07.05 |No |

| |enough | | | | |

|3 |Doesn’t know the|Our department and unit both paid much attention to training, all the testing |Zhang Yuetian|2007.07.05 |No |

| |methods |workers had passed the examinations with high level before they performed | | | |

| | |praitical test jobing. | | | |

|4 |Not familiar |Examination results showed that all the test workers are familiar with the |Zhu Yaohui |2007.07.05 |No |

| |with equipments |operation of testing equipment. | | | |

|5 |No output of |We kept doing maintainance periodically. The defect rates of the testing equipment|Liang Jianxin|2007.07.12 |No |

| |equipment |was totally 0%. | | | |

|6 |Bad screen of |We check the result display before every job so that it can work precisely. |Liang Jianxin|2007.07.12 |No |

| |equipment | | | | |

|7 |Disrepair tools |All tools are 100% up to standard. |Li Xianming |2007.07.12 |No |

|8 |Losing tools |Tools, equipments and meters have been checked before we set out. |Chen Yifeng |2007.07.12 |No |

|9 |Inconvenient and|1、Because the test area is far from the connection site, and it took 2-4(min) to |Yu Zhiwei |2007.07.19 |No |

| |unstable |lay power wire in high -voltage site . | | | |

| |connection of |2、According to the statistic, the probability of wrong turning off power reached| | | |

| |mobile power |40% if many plug were connected to the same power socket. | | | |

| |supply |See the statistics: | | | |

| | |Test line | | | |

| | |Shuang | | | |

| | |Dian | | | |

| | |I line | | | |

| | |Yinjin line | | | |

| | |Yigang line | | | |

| | |Neng Shuang line | | | |

| | |Xinjin line | | | |

| | | | | | |

| | |Turn off power number | | | |

| | |5 | | | |

| | |4 | | | |

| | |3 | | | |

| | |5 | | | |

| | |3 | | | |

| | | | | | |

| | |Error number | | | |

| | |2 | | | |

| | |1 | | | |

| | |0 | | | |

| | |1 | | | |

| | |0 | | | |

| | | | | | |

| | |Time | | | |

| | |(min) | | | |

| | |4 | | | |

| | |3 | | | |

| | |2 | | | |

| | |3 | | | |

| | |2 | | | |

| | | | | | |

|10 |Influences among|This situation seldom took place during the preventive test, because we can |Yu Zhiwei |2007.07.19 |No |

| |different jobs |cooperate with the members of relaying protection team very well. | | | |

|11 |Abominable |Weather is the most important influence factor during the preventive test , so we |Sun Xiuzhen |2007.07.19 |No |

| |weather |don’t start our test in a bad weather. | | | |

|12 |Inconvenient |Mis-arrangement usually happened which disturb changing meters or equipments, and |Tang Minghua |2007.07.19 |Yes |

| |movement and |impacting working mood .According to the investigation, 80% workers considerd they| | | |

| |replacing |fell into a bad mood and work with low efficiency when they encountered such | | | |

| |equipment at |situation. | | | |

| |scene |See the statistics: | | | |

| | |Test line | | | |

| | |Shuang | | | |

| | |Dian | | | |

| | |I line | | | |

| | |Yinjin line | | | |

| | |Yigang line | | | |

| | |Neng Shuang line | | | |

| | |Xinjin line | | | |

| | | | | | |

| | |Investigated number | | | |

| | |6 | | | |

| | |5 | | | |

| | |5 | | | |

| | |6 | | | |

| | |4 | | | |

| | | | | | |

| | |Bad appraisement | | | |

| | |4 | | | |

| | |4 | | | |

| | |5 | | | |

| | |5 | | | |

| | |3 | | | |

| | | | | | |

|13 |The wrong way |The test method has been recognized by technical department. |Wan liju |2007.07.30 |No |

|14 |Inconvenient |1、The breaker of 110 kV, in particular 220 kV is located very high, common |Chen Zihui |2007.07.30 |Yes |

| |connection |insulation ladder can not reach suitable height, at least over 13-grade ladder | | | |

| | |must be taken, so it need more than 2-4 persons to carry the ladder; | | | |

| | |2、The test workers need to work at high altitude so it is very difficult and | | | |

| | |dangerous; | | | |

| | |3、For the test connection, the test workers have to climb down and move to | | | |

| | |another phase breaker again after finished one phase test, and the difficult | | | |

| | |process consumed nearly 40.8(min). | | | |

| | |See the statistics: | | | |

| | |Test line | | | |

| | |One-line double-power | | | |

| | |Yinjin line | | | |

| | |Yigang line | | | |

| | |Neng Shuang line | | | |

| | |Xinjin line | | | |

| | | | | | |

| | |Person | | | |

| | |3 | | | |

| | |3 | | | |

| | |2 | | | |

| | |4 | | | |

| | |4 | | | |

| | | | | | |

| | |Time | | | |

| | |(min) | | | |

| | |40 | | | |

| | |40 | | | |

| | |46 | | | |

| | |40 | | | |

| | |38 | | | |

| | | | | | |

|15 |Wrong test |Clear mark of test line, and simple connection, therefore the wrong test |Chen Zihui |2007.07.30 |No |

| |connection |connection will not happened. | | | |

|16 |Inconvenient |In order to get exact result, we need to use multimeter to measure voltage, and we|Wan Liju |2007.07.30 |Yes |

| |measure |had to climb up and down so the time had to be consumed 15 (min) | | | |

| | |See the statistics: | | | |

| | |Test line | | | |

| | |Shuang | | | |

| | |Dian | | | |

| | |I line | | | |

| | |Yinjin line | | | |

| | |Yigang line | | | |

| | |Neng Shuang line | | | |

| | |Xinjin line | | | |

| | | | | | |

| | |Time | | | |

| | |(min) | | | |

| | |14 | | | |

| | |15 | | | |

| | |14 | | | |

| | |17 | | | |

| | |15 | | | |

| | | | | | |

Lister: Yu Zhiwei Listing date: 2008.02.28

　

We got 4 key factors as the argumentation of key factor in table 4:

★Inconvenient connection ★Inconvenient movement and replacing equipment at scene ★Inconvenient measure ★Inconvenient and unstable connection of mobile power supply

[pic]

VIII. Making Countermeasures

We studied countermeasures as argumentation table of key factors of ratio brake idiocratic , as following:

Table 5 Countermeasure

|Item No.|Factor |Methods |Goal |Measures |Principal |Complete date |

|2 |Inconvenient |Standardization |Be convenient to change meters |Puting test equipments which will |Yu Zhiwei |2007.09.11 |

| |movement and |putting |and transfer direction, build |be used one after another in the | | |

| |replacing | |happy working environment so |appointed area keep the space of | | |

| |equipment at | |that 80% of the good |walking and turning. | | |

| |scene | |appraisement can be reached | | | |

|3 |Inconvenient |Looking for new |Shorten 50% of test measure |Looking for long measure pole so |Chen Zihui |2007.12.24 |

| |measure |measure means |time |that the workers don’t climb up to| | |

| | | | |do measureing | | |

|4 |Inconvenient |Designing a kind of |Reduce 50% of time of |1.Team No. will be stick on the |Lin Meilian |2007.10.10 |

| |and unstable |definite mark of |identification of power supply,|plugs of power; | | |

| |connection of |power supply and |and the number of plug out |2.Avoid the line of power to be | | |

| |mobile power |distribute persons |error is 0. |layed in busy area; | | |

| |supply |to inspect | |3. Appoint the special person to | | |

| | | | |inspect if no any methods. | | |

Lister: Yu Zhiwei Listing date: 2008.02.28

IX. Taking Countermeasures

Measure 1: using tool to avoid climbing (Appointed Chen Yifeng, Deng Zhiqiang and Tang Minghua on November 20th, 2007)

◆The methods we usually take is to clamp the lines by two ends of high voltage connection board of breaker, insulation ladder with more than 13 grades will be needed so that the ladder is heavy enough , it needs two persons at least to carry it, moreover clamping at high altitude is very dangerous, as follow:

[pic]

If there were any tools which could stretch to clamp the high voltage connection board, then we didn’t need to climb up to connect the test lines, furthermore our company’s safety regulations to avoid climbing the breaker .

Are there any tools suitable for the demands? We paid our attention to the ground rod, used the clamp of the ground rod to fix high voltage connection board, utilized ground wire to output current flow, thus to avoid workers climbing up . However , it is inconvenient to carry the ground wire since they’re too heavy . And on the other hand , it took time and hard force to tighten the clamp.

[pic]

In order to make the job more convenient , we searched method from every aspects . We had tried to discuss with the high voltage equipment manufacturers. And finally we found out a very useful clamp which fully meets our need in a manufacturer in Beijing.

[pic]

The picture above is the high altitude clamp which is ready; in the next picture it shows the design of the clamp sub.

[pic]

It is so light and convenient and can reduce our working difficulty by using this high altitude clamp:

[pic][pic]

Checking execution result:

Table 6 Result checking sheet after execution

| |Before execution |After execution |Effect |

|Person number |4 |2 |Reduce 50% |

|Time(min) |40.8 |7 |Decline 83%＞50% |

|Finish or not |Yes |

Lister: Chen Yifeng Listing date: 2007.11.21

In this way, not only our work become easier and safer, but we could carry out by less workers so that the whole working progress of preventive test could be improved.

Table 7 Result checking sheet after execution

|Time shaft | |

|Operators |Allowed | | | | |Time flow of less a |

| | | | | | |test item than |

| | | | | | |before! |

|High voltage |Waiting |Two persons execute|Four persons | | | |

|test team | |breaker test once |execute test PT| | | |

| | | |once | | | |

Lister: Chen Yifeng Listing date: 2007.11.21

Measure 2: Standardization putting tools (Yu Zhiwei, Zhu Yaohui and Zhang Yuetian were appointed on Nov.9th, 2007)

◆The test meters are put in the area which is appointed orderly, so that we can easily fetch them and put them back. The testing line should be orderly placed without any cross or knots.

We failed to appreciate significance of working environment before, we put the tools at will so that it not only blocks working but also affects other’s movement.

[pic][pic]

There has been complete different result at our working site after we took measures , we can work and move with enough space , all of this make us fall into a good mood ,and it increases our work efficiency.

Checking execution result:

| |Working mood |Ratio |

|Respondents list |Chen |

| |Yi |

| |feng |

Table 8 Result checking sheet after execution

Lister: Yu Zhiwei Listing date: 2007.09.11

(Note: Bad is 0-4 score, middle is 5-7 score, good is 8-10 score)

Measure 3: Modify measure means (Chen Zihui, Wan Liju and Liang Jianxin were appointed on Dec. 24th, 2007)

◆At first , we used the high altitude clamp to avoid workers climb the high position for measuring contact resistance by using multimeter , it did save much time and ensure safety, but there was a matter that the clamp sub is too big to clamp the right measuring position, then it limited the choice of measuring point so that the error of contact resistance is probably increased . It would be all right if we had lengthen multimeter-pen. For this, we have observed ground rod.

[pic]

At first , We got a piece of “long-pole” after we took the clamp sub of ground rod apart:

[pic]

[pic]

The metal head was too thick, we found a long wire, fixed one head of it by welding on the metal head of ground rod, the other head could be inserted into the multimeter , so we got our “long-pole-pen”.

[pic]

[pic]

When we used the “long-pole-pen”, we found it was fast and convenient to measure and the value was so steady and accurate.

[pic]

Checking execution result:

Table 9 Result after execution

| |Before execution |After execution |Result |

|Respondents’ number |4 |2 |Reduce 50% |

|Time(min) |15 |6 |Decline 60%＞50% of goal |

|Finish or not |Yes |

Lister:Chen Zihui Listing date: 2007.12.25

Measure 4: designing a kind of definite mark of power supply, appoint persons to inspect (Lin Meilian, Sun Xiuzhen and Li Xianming were appointed on Oct. 10th, 2007)

◆There were so many plugs of mobile power supply in a power board, furthermore , the wires of mobile power supply mixed together, and mobile power supply had to be moved frequently when we are working, all of these cases wasted much time in making out our plug, and usually, it was very easy to make a mistake.

[pic]

We gave numbers to every mobile power supply, we stuck ID labels on every plug of mobile power supply, therefore we could pull out the plug without any mistakes.

[pic]

As the actuality at scene, if we had to put the wire of power supply in the busy area, we would appoint a person to watch.

[pic]

Checking execution result:

Table 10 Result checking after execution

| |Before execution |After execution |Result |

|Error rate |20% |0% |Reduce 20% |

|Time(min) |2-4 |0-1 |Decline 50%= 50% of goal |

|Finish or not |Yes |

Lister: Lin Meilian Listing date: 2007.10.11

IX. Check Result:

According to the statistics , we found that it achieve good results by executing every measure:

1． Workers don’t need to climb insulation post to clamp the holding wire after we adopted high altitude clamp as current output tool, they can operate on the ground, therefore the average time to clamp lines has reduced 33 (min) at all;

2． There is a good order at test scene, it is not only convenient to work and we get a good mood, but also we found an excellent working environment which can help us to save 1 (min) during the whole test process of breaker.

3． The test workers didn’t need to climb up and down so that it ensure safety and economize testing time by nearly 9 (min) ,the measuring time of contact resistance of breaker is largely reduced and it becomes one of our fastest and easiest tests.

4． The error rate of which we putting out the plug is reduced much by using labels so that we saved 2 (min) during the whole process.

We took tests of 110 kV high voltage breaker at Da’ao substation on Jan.12th, 2008, and at Tongguan substation on Feb. 29th, 2008 by using the new tools and measures, and we got satisfying results:

See the following statistics:

Table 11 Statistics of test spending time after improving

|Item No. |Names of test items |Da’ao substation |Muzhou Substation |Average time（min） |

| | |Testing time（min） |Testing time（min） | |

|1 |The time of preparing before test |8.5 |8.6 |8.55 |

|2 |The time of test of operation voltage of |7.4 |7.6 |7.5 |

| |close/open coil | | | |

|3 |The time of test of contact resistance |15 |14 |14.5 |

|4 |The time of test of SF6 |6.9 |7.1 |7.0 |

|5 |The time of recovering after test |4.0 |3.8 |3.9 |

|Average total spending time |41.45（min） |

Lister: Yu Zhiwei Listing date: 2008.02.28

Through the following figure , we found the testing time of contact resistance has declined 35% in the whole consumption time, we believed this item had not been the main matter which influenced the consumption time of breaker test.

Time length N=84.46(min) Add up percentage (%)

[pic]

Figure 7 The sketch map of every spending time after improving

Lister: Yu Zhiwei Listing date: 2008.02.28

With the exciting feelings, now we go back to look at our desired goal, our result was even lower than the target value, we succeeded.

Test spending time

Before QC activity Activity goal After QC activity

Fig 8 Result sketch chart after improving

Mapper: Yu Zhiwei Mapping date: 2008.02.28

[pic]

X. Social Benefit and Experience

We found the method which can help us reduce testing time of high voltage breaker by investigation and discussion in this QC activity, in particular the testing time of contact resistance of 110 kV and 220 kV high voltage breaker, it not only reduced testing time but also economized manpower so that we finished the whole preventive test much faster, furthermore , it also ensured our workers safety.

In this collaborative QC research, and following the PDCA procedures, all the team members have taken their initiatives and have coordinated and collaborated excellently; Meanwhile, the activity has also improved our technical competence and enhanced our team spirits.

Table 12 Statistics of immaterial benefit of QC activity

| |Skill level of team |Cohesion of team |Cooperation ability |Knowledge |QC exertion ability |

|After activity|91 |98 |93 |90 |90 |

[pic]

Figure 9 Analysis chart of immaterial benefit of QC activity

Mapper: Yu Zhiwei Mapping date: 2008.02.28

XI. Consolidation Measures and Period

We compiled Test Improving Report of High-voltage Circuit Breaker after we improved test method and process, which was approved by the leaders our department, and was incorporated into Test Manual of High-voltage Circuit Breaker, it was rapid to be acknowledged and extended by our brother team, some of the methods also work in other type of test.

Then how to consolidate our achievement?

At first, we should study and execute every rule regulated by our department, this is to ensure production and work safety and it is the base to promote work efficiency.

Secondary, every new member must accept skill training in every aspect.

They must master rules and skill so that they can improve and expert by themselves.

The track record on the test consumption time of breaker in the succedent preventive test task after our team held the activity as following:

Table 13 Statistics of test spending time of daily work after activity

|Item No. |Name of test item |110 kV Tongguan Substation, at 152 of Tongnan line |

| | |Testing time（min） |

|1 |The time of preparing before test |8.30 |

|2 |The time of test of operation voltage of |7.50 |

| |close/open coil | |

|3 |The time of test of contact resistance |12.50 |

|4 |The time of test of SF6 |7.1 |

|5 |The time of recovering after test |4.5 |

|Total spending time |39..90 |

Lister: Yu Zhiwei Listing date: 2008.02.28

This shew that our achievement could be executed very well during the task, the realities proved our achievement was so effective, our endeavor was not wasted, we were happy that much time had been reduced.

[pic]

XII. Problem and Future plan

Although we improved much during this QC activity, but we have to acknowledge that we still need to measure manually, the matter of precision error when measuring has not been settled, so we need to probe into the relative manufacturer.

We didn’t hug ourselves on this achievement in this QC activity so that to stop our progress. As to the long consumption time in our preventive test and inefficient items, we will hold a new round of QC activity, Our intended title is “Improving Work Efficiency of Measuring Transformer winding”.

[pic]

-----------------------

The consumption time of test of contact resistance

35.5(min)

Tidy meters and changing the meters of next test

The end

The consumption

time of test of SF6

The consumption time of preparation before test working

1ÿmin ÿ

84.48(min)

90.61%

73. of contact resistance

35.5(min)

Tidy meters and changing the meters of next test

The end

The consumption

time of test of SF6

The consumption time of preparation before test working

1（min）

84.48(min)

90.61%

73.72%

55.63%

5（min）

Lack of skill

35.00%

Bad screen of equipment

Shortening the Time of High-voltage Circuit Breaker Preventive Test of 110 kV and Above

Wrong test connection

Bug of equipment

No output from equipment

Influences among different jobs

Doesn’t know the methods

Abominable weather

Inconvenient connection

The test interval of high-voltage circuit breaker 110 kV or over is long and the progress is slow: for 4 persons have to execute breaker test to result in other tests have to be executed orderly so that operators complain.

The test should be finished as soon as possible to ensure the time of power supply and safety.

Ensuring normal power supply so that to reduce power cuts time and load loss

Difficulties encountered

Demands of department

Demands of power supply

5（min）

52(min)

13（min）

84.46（min）

5（min）

41.45 (min)

52(min)

Recovering connection and checking whether gas leaks

1（min）

3（min）

The test of C-phase contact resistance

13.5（min）

Test of SF6

2.5（min）

Record and analysis of the test date

The connection of SF6 test

Changing the connection to C-phase

Equipment

The test of B-phase contact resistance

Changing the connection to B-phase

96.29%

89.04%

80.37%

71.63%

110 kV and above high voltage circuit breaker test ,with lots of difficulty and time wasting , person number and time occupy the most of part of the whole test progress (they are 66% and 40%) is main matter to impact the progress of the whole test.

[pic]

Inconvenient measure

3（min）

Record and analysis of the test date

The consumption

time of recovering

after test

The consumption

time of test of C/O coil

1（min）

A-phase contact resistance test of breaker

Inconvenient movement and replacing equipment at scene

The wrong ways

Losing tools

Disrepair tools

The tools which test needs are not on deck

Bad cooperation

Ambiguous task distribution

Environment

Technician

Spent long time in the test of contact resistance of breaker

Not familiar with equipments

Backward measure method

Fig 6 Analysis chart of cause and effect of long testing time of contact resistance of breaker

Inconvenient and unstable connection of mobile power supply

Method

Manpower is not enough

2（min）

2 (min)

14（min）

2（min）

3（min）

3（min）

2（min）

2（min）

2（min）

The connection of contact resistance test of breaker

Re-arrangement and changing test meters and tidy last test meters

Test of C/O coil

Checking relative nameplates of breakers

The connection of voltage test of C/O coil

Checking and accepting high voltage circuit breaker and reclaim tools and meters

The equipments will be arranged at scene, power supply will be connected

Meters, equipments which need and tools necessary before start working

The explanation at scene and arrange the workers

Start

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