5/24/2018 06021756

1/4

2011 International Conference on Electrical Engineering and Informatics

17-19 July 2011, Bandung, Indonesia

In-Service Early Indication of 500 kV Circuit

Breaker Function Loss Operated in PLN P3B

Jawa Bali IndonesiaY. Wibisana,R.Setyo Wibowo,H. Maryono

PT. PLN (Persero) P3B Jawa Bali- Jakarta

PT. PLN (Persero) P3B Jawa Bali RJBR, Jl. M TOHA Km 04 Bandung, Indonesia1yokeu.wibisana@pln-jawa-bali.co.id

1rintoko.sw@pln-jawa-bali.co.id2hendrik.m@pln-jawa-bali.co.id

Abstract Since year of 2004 PLN P3B Jawa Bali has beenchanging its maintenance strategy from time based to the

combinations of time-based and condition-based maintenance.

Currently, as part of the new strategy PLN P3B Jawa Bali has

been implementing a visual inspection and early indication of

equipment function loss by using visual inspection, in-service

monitoring and on-line measurement.

. This early indication uses critical failure modes of visual

inspection item and thermovision as its input. The critical failure

modes are identified by using FMEA /FMECA which were

developed based on statistical data and engineering senses. The

output of the early indication are either 1,6 or9 in which 1

represents bad, 6 fair and 9 good conditions. By using this in-

service early indication of function loss, we will able to obtain

symptoms to equipment failure earlier.Keywords circuit breaker, in-service early indication of function

loss, fmea/fmeca

I. INTRODUCTIONIn order to improve the quality of maintenance, availability

and reliability of electrical energy supply and reduce the

maintenance costs, PT PLN (PERSERO) Jawa Bali has

changed its maintenance strategy for both primary and

secondary equipment. Among others, condition-based

maintenance (CBM) strategy of circuit breaker (CB) has been

introduced to reduce time-based maintenance (TBM) scheme.

Figure.1 Maintenance concept

The goal of Maintenance improvement in P3B Jawa Bali is

for minimize Time Base Maintenanceand, corrective

maintenance and then to maximize the job function ofsubstation operator, this time the operator have a bigger

portions operational function its like recorded current,voltages

and load. In future we want to changed the paradigm and

mindset of substation operator for maximized maintenance

function . Maintenance function are covered visual inspection

and reporting the anomally by the CBM application that we

developed beside still recorded the currents, voltages and

load,.

In the past years, TBM was proven to be ineffectively

reduce system faults. In TBM the circuit breaker was

measured and maintained once a year . In 2008 the period was

extended to 2 years. Unfortunately in some occasions some

faults occurred after the maintenance have been done. Besidethat we must spend for TBM cost every year.

According to P3B Jawa Balis equipment database in,

32.52 % of CB total population has technical lifetime of 16-

20 years. 500 kV CB is one of the most crucial because 500

kV transmission system is the backbone of electrical energy

supply. Based on these reasons, we will focus on in-service

early indication of 500 kV CB, in particularly the

implementation on inspection level 1 (visual inspection).

Figure. 2 Technical lifetime distribution of 500 kV CB.

Years

E14 - 7

978-1-4577-0752-0/11/$26.00 2011 IEEE

5/24/2018 06021756

2/4

II. FMEAA large number of CB types are installed in PLN P3B Jawa

Bali. In order to simplify the analysis we classified the CB

based on its operating voltages. For further development CB

will be classified based on its type.

In analysing the failure mode and effects, CB is defined as

one system. Furthermore, it is divided into five subsystems

based on its function, namely primary, secondary, dielectric,

driving mechanisms and supporting part subsystems. For each

subsystem we define its failure modes and the root cause(s) of

each possible and occurred failure modes. The failure modes

of each CB subsystem are used as a reference in developing

and optimizing the maintenance programs because the

program not only focuses on the most critical subsystem, but

also the most critical failure mode.

The symptoms of possible failures of each subsystem are:

Primary - Damage due to excessive cumulative interrupting

duty, overheated contact, overheated clamp, objects attached

on clamp (kite), floating contacts, capacitor and resistor

breakdown.

Secondary Loss of power supply, moisture in control box ,

shorted circuit coils, abnormally fan heating, short circuit of

control cable, or open circuit from termination failure,

corrosion termination.

Dielectric Broken insulator chamber, contaminated oil, oil

leakage, low pressure of SF6and low pressure of air blast

Driving mechanism - Mechanical issues such as faultylinkages, faulty latches, ageing seal, pipe leakage and

malfunctions of spring, pneumatic or hydraulic system. These

problems may either gradually degradation, or rapid

development from a component failure.

Supporting part Sloping foundation, broken support

insulator, broken steel/concrete structure and grounding

problems.

III.FMECAAfter performing FMEA and finding the root causes of

failures, we continue to conduct FMECA. A failure mode is

considered to be critical if its risk level is high enough,according to the utility. We need to calculate the probability

and effects of each failure mode to determine the most critical

failure mode of a circuit breaker. The failure probability are

obtained from statistical failure information which were

collected from a brainstorm sessions of engineers, corrective

maintenance data and failure record. PLN P3B Jawa Bali hasbeen developing an application that record all failures

occurred in the transmission system, namely FOIS (Forced

Outage Information System). In this analysis we use failure

record data from 2008 until 2010.

In calculating the effect of each failure modes, we use four

four criteria which is described hereafter.The score of each effect is defined based on the result of

the brainstorm sessions and discussion within switchgear

working group.

FREQUENCY

Score Frequency1 Rarely (30%)

SAFETY

Score Frequency

1 No life threatening

7 Life threatening

ENVIRONMENT

Score Frequency

1 No impact

3 Easy to clean / treat

5 Need work to restore

SYSTEM

Score System outage

1 No system impact

2 8 hours

3 > 8 h dan 32 h

4 > 32 h dan 7 days

5 Total out of operation

CORRECTIVE COST

1 Minor (300 MRp)

A. Scores of FMECAThe scores in FMECA is obtained by multiplying the

probability to the effects, as shown in the following formula.

Risk = Probability x Effects (safety + environment + system +

corrective cost)

The accuracy of this calculation is verified by mapping the

calculated risk on a risk matrices as shown on figure below.

Ideally, the calculated risk should be spread evenly .

Otherwise, the score of each criteria should be adjusted .

5/24/2018 06021756

3/4

Figure.3 Risk metrics

The list of critical failure modes and components are hence

used to create a checklist items of In-Service Early Indication

and inspection period. We classified the inspection period into

daily, weekly, monthly and annually, depend on how critical

is the failure modes and the components are.

The inspection period of In-Service Early Indication on CB

are:

annually or monthly if the risk is low risk monthly, if the risk is average weekly or daily, if the risk is high

IV.IN-SERVICEEARLYINDICATIONOF FUNCTIONLOSSCB

The In-Service Early Indication is intended to conduct the

inspection level 1 (visual inspection). It is conducted by

optimizing 5 (five) human sense and completed with some

simple monitoring tool, for example the binocular. In-Service

Early Indication of CB are including the visual inspection and

thermovision camera. Other critical components that are

impossible to be inspected through visual inspection has to be

measured through offline measurement.

The result of visual inspection of each component condition is

categorized into. normal condition and anomaly condition.

Then we scores these conditions by using the following

number: 1, 6 and 9. These number represents the following

conditions:

1 : bad condition 6 : fair condition 9 : good condition

The purpose of In-Service Early Indication 500 kV Function

Loss is to record anomalies of each component and initiated

maintenance recommendation.

In order to describe how the system works, we take the

inspection on driving mechanism subsystem as the example.

In visual inspection we monitor the spring condition. The

condition of spring is categorized into

9 ( good ): full charged: 1 ( bad ): not charged :

Note: there is no fair condition.

Another example is monitoring a grounding cable condition

of supporting part subsystem. we categorized the grounding

cable condition into:

9: normal, 6: corotion 1: loose,broken

In the following figure below showed the daily visual

inspection applications in 500 kV circuit breaker for SF6 and

spring mechanism type. We monitored pressure of SF6 and

spring condition.

Figure.4 Dailly visual inspection application

5/24/2018 06021756

4/4

After notifying the anomalies of the circuit breaker, we

determine:

Maintenance recomendationMaintenance recomendation is determined based on

bad or fair condition of a component

Time interval of maintenanceTime interval of maintenance is determined based on

ageing process knowledge and maintenance

experience

Maintenance recomendations are including :

o Simple maintenance which conducted by operator orSupervisor assistant of a substation

o Complex maintenance which conducted by amaintenance team

o On line minitoring that we called inspection level-2o Advanced inspection/measurement that we called

inspection level-3 . This inspection/measurement can

be either on-line or shutdown measurement

o Shutdown investigationIn-Service Early Indication of Function Loss in circuit breaker

that we called inspection level 1 (visual inspection) has been

implemented in PLN P3B Jawa Bali using an applications that

have been developed by PLN P3B Jawa Bali.

V. SUMMARIESAND CONCLUSIONS1. PT. PLN (Persero) P3B JB is in a way to change the

maintenance method by applying the CBM method .

2. The process of FMEA/FMECA will be evaluatedcontinuously and it still needs further knowledge todeveloping this complete CBM CONCEPT, BECAUSE this

paper only focusing on implementation on In-Service

Early Indication of Function Loss in circuit breaker.

3. Nowadays, In-Service Early Indication of 500 kV CircuitBreaker Function Loss has been implemented in PLN P3BJawa Bali and still needs improvement to developed the

application.

REFERENCES

[1] John Moubray, Reliabilty-centered maintenance, Secondedition ,May 2000.

[2] PLN P3B, Equipment assessment tools, October 2010[3] Frank de Vries, Frans de Rijke, Theo van Rijn, Review CBM

approach PLN General, KSANDR, February 2010.[4] Edwin R.S. GROOT, Edward GULSKI, Abe van DAM, Frank J.

WESTER Successful implemented condition based maintenanceconcept for switchgear, CIRED session, May 2003 ,paper no-14