OBJETIVE:The objective is to present the replacement and re-connection job (doing Live Line Work) of an SF6 breaker unit, from S&C, in the 115 kW & 20 MW substation of Join Operations, in SUG oil field, Kuwait.

DEVELOPMENT:After more than 5 years working for different utilities, ELESA S.A., which is a company dedicated to maintenance, consulting and Live Line training in both local and international levels, did contact with IMCO company which carries out construction and maintenance projects in Kuwait and other Middle East countries. An agreement between companies was established, that allow us to complement and enrich ourselves.

In this opportunity the challenge was to replace an SF6 breaker unit, from S&C, that was failed due to gas leakage.

It was located in a radial substation that supplies 20 MW to the high production SUG Oil Field.

In the emergency, and in order to restore the power supply, the complete circuit-switcher was by-passed, and a shutdown was programmed to replace the interrupter.

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COMISIÓN DE INTEGRACIÓN ENERGÉTICA REGIONAL

REPLACEMENT OF CIRCUIT-SWITCHER IN 115 KV SUBSTATION

Author/s: Carlos ArataCompany: ELESA International S.A.Author/s: Jalal Mohesen – Pablo JuradoCompany: IMCO Engineering & Construction Co.

COMPANY INFORMATIONELESA SATelephone: (54) 93461 512966E-mail: info@elesa.com.ar

c.arata@elesa.com.arIMCOAddress: P.O. Box 9309 Ahmadi, KuwaitZip Cod: 61004Telephone: (965) 2398 1661Fax: (965) 2398 4708E-Mail: pjurado@imcokw.com

jmohsen@imcokw.com

KEY-WORDS: Uninterrupted production – Innovation – Complementation between companies

COMPANY: ELESA SA - IMCO Engineering & Construction Co. COUNTRY: KuwaitType: Technical Paper Kuwait, May 2011.

By-passed circuit-switcher

By chance I was giving training and refreshment course to the Live Line crews when I knew about the equipment failure. It seems to me and interesting challenge, and us when to see the substation.

The job to be carried out was similar to others that we have already made at the 66 kV substation of EDEN Company in Argentina.

But the two main differences were, by one side, the unavailability in Kuwait of the equipment that ELESA has for substation jobs, and by the other side, the generous safety distances in the substation portal structure.

After discussing the possibility of doing the job by applying Live Line Work, the scheduled shutdown was suspended.

The similar jobs previously done consisted in by-passing measurement and operation equipments, for maintenance, which avoided the replacement of them, thing that made no sense at that time. We did these types of jobs since 2002, when we finished the construction of the prototype for working in substations.

By-pass 66 kV Substation, EDEN, October 2003

Steps of the task Basically the Live Line Work in this case consisted of 4 main steps which are:

1) Replacement of the failed breaker unit

2) Circuit-Switcher-to-Surge Arrester jumpers installation

3) Circuit-Switcher-to-Line jumpers installation

4) Removal of the temporary by-pass jumpers and old jumpers from line-to-circuit switcher (having close the circuit-switcher previously)

1) Replacement of failed breaker unit

The failed unit was the middle one, which is the most difficult to work on, for all steps.

Two Class A, approved to work up to 132 kV, insulated lift, were used to do the job.

We had to study carefully the safety distance to work on the installation.

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General view and distances

The lift trucks that we used have two articulated booms, with the upper one telescopic (Class A). These features make them quite versatile to work in complicated installations, giving as good flexibility to find the most suitable position. Besides this, they have a material handling system with 700 lbs capacity in the worst condition. We used this feature to remove the failed unit and to install the new one (Step 1, see the following picture)

Installing the new SF6 unit

2) Transformer side jumper installation

One again here the more complicated to install was the central phase jumper, to which we had access by positioning the bucket between the insulators of the circuit-switcher. In order to connect the circuit-breaker with the jumpers on the surge arrester, and due to there wasn’t enough room to work by barehand method, we installed a jumper by using hotsticks, made of extra-flexible cooper conductor (120 mm²) mechanically reinforced with an extra-flexible steel wire, and with two duckbill clamps of 400 A capacity each one, which was much more than we need, an also this feature allowed us to handle the jumper by using two sticks, therefore improving the safety at the work.

3) Circuit-switcher-to-line jumpers installation

The jumpers to be installed were 6 m long. First they were installed in the pedestal insulator of the open switch, and then in the lug of the tension clamp.

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Leaving the lug free

But as n the lug there was the existing permanent jumper still connected forming a loop in which the by-pass was installed, before connecting the new jumper a piece of the old jumper had to be removed.

In this case, due to the distances at the portal side are wide enough there is no difference in starting to work in the middle phase or in the lateral ones.

Going up with the new jumper

The new jumper was attached first to the main conductor using a short flexible jumper, before connecting both lugs. This short jumper took the capacitive load of the new jumper and mechanically insures the connection to avoid an unexpected drop of the jumper.

Fixing the new jumper to the dead-end terminal

4) Removal of the temporary by-pass jumpers and old jumpers from line-to-circuit switcher (having closed the circuit-switcher previously)

Once the new permanent jumpers have been connected, it was missing to remove the temporary by-pass jumpers installed during the emergency, and the original jumpers from line-to-switch that were tied back forming a loop.

This task was done working with simultaneously with two insulated lifts, due to they were available as well as the necessary personnel.

The synchronization of the task was in charge of the supervisor on ground, and the good communication was insured by using walkie-talkies.

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The operation of disconnection of the by-pass was made with hotsticks according to the fundamentals of the barehand method, in order to eliminate any possibility of one lineman to be in series with the circuit.

Preparation to disconnect the by-pass

The by-pass jumper to be removed was still attached to the old piece of jumper by an insulated rope, which is lately removed, while the other crew picked-up the by-pass jumper.

The other crew removes the by-pass jumper

Removal of the by-pass jumper with two crews working together

Having completed the above mentioned step, the last thing to do was to remove the old permanent jumpers, which were cut in three pieces to avoid they were opened due to their elastic memory while removing, since, we must remember, these jumpers were 6 m long.

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CONCLUSIONS

The technician that was sent by S&C (the manufacturer of the equipment to be replaced) didn’t know about the possibility to do this job Live, although it could done in a safe way and according to the previously developed procedure.

The execution of this Live Line Work avoided a costly shutdown to the oil company, that was planned to be of at least 8 hours with a loss of approximately u$s 1 million in differed oil.

In addition the execution of this job is an important precedent to introduce the concept of Live Line Work in Substations that had never been considered before in this country.

LESSON LERNTThe conjunction of qualified personnel, and necessary equipment together with the team work for the development of the procedure and the explanation of it to the people who make the decisions (which showed reluctant at the beginning), allowed the completion of a this kind of job for the first time in the country and probably in all Gulf area.

RECOMENDATION

Start thinking that a Live Line Work in Substation is possible until the contrary is demonstrated, don’t think in the reverse way.

Site work team

ELESA SA

Carlos Arata

IMCO

Pablo JuradoKhaled Alí ManssurMohamed Abou EleninNabil Abd el MohesenAhmed Sultan MohamedMohamed Abdul GhaniMohamed Khalaf ShakoorRheda MohamedV. Perumal

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COMISIÓN DE INTEGRACIÓN ENERGÉTICA REGIONAL