Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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.
Table 1 Registration form of group members
Group name
Group type
Chen Yifeng QC group
Gour
Task
name
Scene type
Shortening the Time of High-voltage Circuit Breaker Preventive Test of 110 kV and Above
Activity number
11
Activity date
Registration
times
Sep. 21st, 2007
Date
Registration
2007.07.21 -2008.02.29
NO：
07A-02
number
TQC
Name
Gender
Age
Level
Title
education
time （h）
Working Distribution in the
group
Chen Yifeng
Male
44
Technical secondary school
Monitor
108
Director
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
Lister：Yu Zhiwei
NO. 0
Sheeting date：2008.02.28
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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.
Ensuring normal power supply so that to reduce power cuts
Demands of power supply
time and load loss
The test should be finished as soon as possible to ensure
Demands of department
the time of power supply and safety.
The test interval of high-voltage circuit breaker 110
Difficulties encountered
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.
Time shaft
Work
grouping
Operators
30-50min
60min-85min
40-55min
3 persons test
4 persons test
CT
PT
/
Permit
High
voltage test
30-40min
Waiting
4 persons test Breaker
group
The time of test
confirme
restart power
Relaying
team
and
is
very urgent.
Waiting
Protection test
Rest
Linkage test
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.
Shortening the Time of High-voltage Circuit Breaker Preventive Test of 110 kV and Above
Fig I
Argumentation chart of selection of title
Mapper: Yu Zhiwei Listing date: 2008.02.28
NO. 1
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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
Rank of breaker
Statistic
Average consumption time of the
voltage
number
test（min）
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
Item No.
Test date
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:
Start
2（min）
The explanation at scene and arrange the workers
preparation before test
The consumption time of
time of test of C/O coil
The consumption
working
2（min） Meters, equipments which need and tools necessary before start working
2（min）
The equipments will be arranged at
Checking relative
scene, power supply will be connected
nameplates of breakers
The connection of voltage
3（min）
test of C/O coil
2（min）
Test of C/O coil
2（min）
14（min）
Re-arrangement and changing test meters and tidy last test meters
The connection of contact resistance test of breaker
NO. 2
2 (min)
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
35.5(min)
The consumption time of test
of contact resistance
5（min）
13（min）
5（min）
A-phase contact resistance test of breaker
Changing the connection to B-phase
The test of B-phase contact resistance
13.5（min）
Changing the connection to C-phase
5（min）
The test of C-phase contact resistance
1（min）
Record and analysis of the test date
3（min）
2.5（min）
The consumption
time of test of SF6
3（min）
1（min）
Chen Yifeng QC group
Tidy meters and changing the meters
of next test
The connection of SF6 test
Test of SF6
Record and analysis of the test date
Recovering connection and checking
1（min）
whether gas leaks
The consumption
time of recovering
after test
3（min） Checking and accepting high voltage circuit breaker and reclaim tools and meters
The end
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)
NO. 3
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
Table 3 Statistics of every consumption time
Item No.
1
Total time length（min） Average time length （min） Add up（%）
Item name of test
The time of preparing before test
153
6.12
07.25%
184.5
7.38
15.98%
1512.5
60.5
87.62%
The time of test of operation voltage of
2
close/open coil
3
The time of test of contact resistance
4
The time of test of SF6
183
7.32
96.28%
5
The time of recovering after test
78.5
3.14
100%
2111.5(min)
Total time length
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 (%)
80.37%
80
70
60.5
96.29%
89.04%
100
90
80
71.63%
60
70
50
60
40
50
40
30
30
20
7.38
10
7.32
6.12
N
O
.
4
N
O
.
1
20
3.14
0
N
O
.
3
N
O
.
2
10
0
N
O
.
5
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.
NO. 4
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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:
84.46
（min）
52(min)
Before QC activity
Fig 4
Activity goal
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
NO.2
8.74%
more time is spent in the process of test.
2.We can see from the actual data which is
NO.5
3.71%
NO.4
8.67%
investigated , the main time wasting part
NO.1
7.25%
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
NO.3
71.63%
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.
NO. 5
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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:
Technician
Environment
Ambiguous task distribution
Inconvenient and unstable connection
of mobile power supply
Bad cooperation
Doesn’t know the methods
Influences among
Manpower is not enough
Lack of skill
different jobs
Inconvenient movement and
Not familiar with equipments
Abominable weather
replacing equipment at scene
Spent long
time in the
test of
contact
resistance
Disrepair tools
No output from equipment
The wrong ways
of breaker
The tools which test
Bug of equipment
needs are not on deck
Bad screen of equipment
Equipment
Wrong test connection
Backward measure
method
Losing tools
Method
Inconvenient connection
Inconvenient measure
Fig 6 Analysis chart of cause and effect of long testing time of contact resistance of breaker
Mapper: Yu Zhiwei
NO. 6
Mapping date: 2008.02.28
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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
Factors
No.
Argumentation Descriptions
Checker
Ambiguous
1
task
The works will be arranged in the daily meeting before every job.
distribution
Manpower
2
is not
enough
3
Our department and unit both paid much attention to training, all the
testing workers had passed the examinations with high level before they
methods
performed praitical test jobing.
with
No output of
equipment
Examination results showed that all the test workers are familiar with the
of
8
Disrepair
tools
Losing tools
Zhang
Yuetian
Zhu
Yaohui
We kept doing maintainance periodically. The defect rates of the testing
Liang
equipment was totally 0%.
Jianxin
We check the result display before every job so that it can work precisely.
equipment
7
Deng
operation of testing equipment.
Bad screen
6
Yifeng
Zhiqiang
Doesn’t
equipments
5
workers .
know the
Not familiar
4
Through all the test,we seldom failed the job to the lack of testing
Chen
Liang
Jianxin
Li
All tools are 100% up to standard.
Xianming
Tools, equipments and meters have been checked before we set out.
Chen
Yifeng
Checking
Main
Date
Cause
2007.07.05
No
2007.07.05
No
2007.07.05
No
2007.07.05
No
2007.07.12
No
2007.07.12
No
2007.07.12
No
2007.07.12
No
2007.07.19
No
2007.07.19
No
1、Because the test area is far from the connection site, and it took
2-4(min) to lay power wire in high -voltage site .
2、According to the statistic, the probability of wrong turning off power
Inconvenient
and unstable
connection
9
of
mobile
power
supply
reached 40% if many plug were connected to the same power socket.
See the statistics:
Shuang
Test
Dian
line
I line
Turn
off
5
power
number
Error
2
number
Time
4
(min)
Yinjin
line
Yigang
line
Neng Shuang
line
Xinjin line
Yu
Zhiwei
4
3
5
3
1
0
1
0
3
2
3
2
Influences
10
among
This situation seldom took place during the preventive test, because we
Yu
different
can cooperate with the members of relaying protection team very well.
Zhiwei
jobs
NO. 7
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Abominable
11
weather
Chen Yifeng QC group
Weather is the most important influence factor during the preventive test ,
so we don’t start our test in a bad weather.
Sun
Xiuzhen
2007.07.19
No
2007.07.19
Yes
2007.07.30
No
2007.07.30
Yes
2007.07.30
No
2007.07.30
Yes
Mis-arrangement usually happened which disturb changing meters or
equipments,
12
and
impacting
mood
.According
to
the
Inconvenient
investigation, 80% workers considerd they fell into a bad mood and work
movement
with low efficiency when they encountered such situation.
and
See the statistics:
replacing
Tang
Test line
equipment at
scene
Shuang
Dian
I line
Yinjin
line
Yigang
line
Neng
Shuang
line
Xinjin
line
6
5
5
6
4
4
4
5
5
3
Investigated
number
Bad
appraisement
13
working
The wrong
way
The test method has been recognized by technical department.
Minghua
Wan liju
1、The breaker of 110 kV, in particular 220 kV is located very high,
common 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;
14
Inconvenient
3、For the test connection, the test workers have to climb down and move
Chen
connection
to another phase breaker again after finished one phase test, and the
Zihui
difficult process consumed nearly 40.8(min).
See the statistics:
One-line
Test
double-power
line
Person
Time
(min)
15
Yinjin
line
Yigang
line
Xinjin
line
2
Neng
Shuang
line
4
3
3
40
40
46
40
38
4
Wrong test
Clear mark of test line, and simple connection, therefore the wrong test
Chen
connection
connection will not happened.
Zihui
In order to get exact result, we need to use multimeter to measure voltage,
and we had to climb up and down so the time had to be consumed 15
(min)
16
Inconvenient
measure
See the statistics:
Shuang
Test
Dian
line
I line
Time
14
(min)
Wan Liju
Yinjin
line
Yigang
line
15
14
Neng
Shuang
line
17
Xinjin
line
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
measure ★Inconvenient and unstable connection of mobile power supply
NO. 8
★Inconvenient
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
VIII. Making Countermeasures
We studied countermeasures as argumentation table of key factors of ratio brake idiocratic , as following:
Table 5
Item
Factor
No.
1
Methods
Inconvenient Use tool to avoid
connection
climbing
replacing
2
equipment at
Standardization
putting
Shorten 50% of test
connection time
build happy working
suitable
Complete date
long
handle tools to avoid workers Chen Yifeng 2007.11.20
climbing up and down.
will be used one after another in
Yu Zhiwei
2007.09.11
so that the workers don’t climb Chen Zihui
2007.12.24
reached
Looking for new
Shorten 50% of test
measure
measure means
measure time
definite mark of
connection of power supply and
mobile power distribute persons
supply
for
environment so that 80% of the appointed area keep the
Inconvenient
and unstable
Looking
Principal
the good appraisement can be space of walking and turning.
Inconvenient Designing a kind of
4
Measures
meters and transfer direction, Puting test equipments which
scene
3
Goal
Be convenient to change
Inconvenient
movement and
Countermeasure
to inspect
Looking for long measure pole
up to do measureing
1.Team No. will be stick on the
Reduce 50% of time of
plugs of power;
identification of power
2.Avoid the line of power
to
supply, and the number of be layed in busy area;
plug out error is 0.
Lin Meilian
2007.10.10
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 20 th,
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:
NO. 9
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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.
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.
NO. 10
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
The picture above is the high altitude clamp which is ready; in the next picture it shows the design of the clamp sub.
It is so light and convenient and can reduce our working difficulty by using this high altitude clamp:
NO. 11
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
NO. 12
Chen Yifeng QC group
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
Checking execution result:
Table 6 Result checking sheet after execution
Before execution
After execution
Effect
Person number
4
2
Reduce 50%
Time(min)
Finish or not
40.8
7
Decline 83%＞50%
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
High
voltage test
team
Allowed
Relaying
team
Waiting
Waiting
Time flow of
Two persons execute
breaker test once
Three persons
execute test CT
once
Protection test
Rest
Four persons
execute test PT
once
less a test item
than before!
Linkage test
Lister: Chen Yifeng
Listing date: 2007.11.21
Measure 2: Standardization putting tools (Yu Zhiwei, Zhu Yaohui and Zhang Yuetian were appointed on Nov.9 th, 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.
NO. 13
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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:
Table 8 Result checking sheet after execution
Respondents list
Appraised score
before execution
Appraised score
after execution
Working mood
Wan Zhu Zhang
Li
Yao Yue
ju
hui
tian
Chen
Yi
feng
Chen
Zi
hui
Yu
Zhi
wei
Liang
Jian
Xin
Deng
Zhi
qiang
3
4
4
6
4
5
3
2
8
9
8
8
9
9
8
9
Finish or not
Ratio
Lin
Mei
lian
Sun
Xiu
zhen
Li
Xian
ming
Tang
Ming
hua
3
4
3
4
8
9
9
9
83%
bad appraisement
100% good
appraisement
Yes
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. 24 th, 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.
NO. 14
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
At first , We got a piece of “long-pole” after we took the clamp sub of ground rod apart:
NO. 15
Chen Yifeng QC group
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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”.
NO. 16
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
When we used the “long-pole-pen”, we found it was fast and convenient to measure and the value was so steady and accurate.
NO. 17
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
Checking execution result:
Table 9 Result after execution
Before execution
After execution
Respondents’
number
4
2
Reduce 50%
Time(min)
15
6
Decline 60%＞50% of goal
Finish or not
Result
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. 10 th, 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.
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.
NO. 18
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
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.
Checking execution result:
Table 10 Result checking after execution
Error rate
Time(min)
Finish or not
Before execution
After execution
20%
2-4
0%
0-1
Yes
Result
Reduce 20%
Decline 50%= 50% of goal
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:
NO. 19
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
Table 11 Statistics of test spending time after improving
Item
No.
1
2
Names of test items
Da’ao substation
Testing time（min）
Muzhou Substation
Testing time（min）
Average time（min）
8.5
8.6
8.55
7.4
7.6
7.5
The time of preparing before test
The time of test of operation voltage of
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 (%)
40
73.72%
30
20
100
90
80
70
60
50
40
30
20
10
0
90.61%
55.63%
14.5
35.00%
8.55
10
7.5
7
3.9
0
3
N
O
.
1
N
O
.
2
N
O
.
N
O
.
4
5
N
O
.
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
84.48(min)
52(min)
41.45 (min)
Before QC activity
Activity goal
Fig 8
After QC activity
Result sketch chart after improving
NO. 20
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
Chen Yifeng QC group
Mapper: Yu Zhiwei
Mapping date: 2008.02.28
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
70
75
73
72
75
91
98
93
90
90
Before
activity
After
activity
Skill level of team
100
活动前
活动后
50
QC exertion ability
Cohesion of team
0
Knowledge
Cooperation ability
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.
1
Name of test item
110 kV Tongguan Substation, at 152 of Tongnan line
Testing time（min）
8.30
The time of preparing before test
NO. 21
Shortening the time of high voltage circuit breaker preventive test 110 kV and above
2
The time of test of operation voltage
Chen Yifeng QC group
7.50
of close/open coil
3
The time of test of contact resistance
4
The time of test of SF6
7.1
5
The time of recovering after test
4.5
12.50
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.
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”.
NO. 22