REPLACE 230 KV CIRCUIT BREAKER - Public Utilities Board€¦ · Circuit breaker L03L06 was manufactured by Brown Boveri and was installed in 1966. It is 44 years old. Newfoundland

A REPORT TO

THE BOARD OF COMMISSIONERS OF PUBLIC UTILITIES

Electrical

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LAND&Telecontrol

System Planning

REPLACE 230 KV CIRCUIT BREAKER

Sunnyside Terminal Station

April 2010

newfoundland labrador

h droa nalcor energy company

Replace 230 kV Breaker Sunnyside Terminal Station

Table of Contents

1

INTRODUCTION 1

2

PROJECT DESCRIPTION 3

3

EXISTING SYSTEM : 43.1

Age of Equipment or System : : 53.2

Major Work and/or Upgrades 63.3

Anticipated Useful life 63.4

Maintenance History 63.5

Outage Statistics 63.6

Industry Experience 73.7

Maintenance or Support Arrangements 73.8

Vendor Recommendations 73.9

Availability of Replacement Parts 83.10 Safety Performance 83.11 Environmental Performance 83.12 Operating Regime 8

4

JUSTIFICATION 9...................4.1

Net Present Value 94.2

Levelized Cost of Energy 94.3

Cost Benefit Analysis 94.4

Legislative or Regulatory Requirements 94.5

Historical Information 104.6

Forecast Customer Growth 104.7

Energy Efficiency Benefits 104.8

Losses during Construction 104.9

Status Quo 104.10 Alternatives 10

5

CONCLUSION 125.1

Budget Estimate 125.2

Project Schedule 13

Newfoundland and Labrador Hydro


1

INTRODUCTION

Newfoundland and Labrador Hydro (Hydro) owns and operates 54 terminal stations in the

Island Interconnected System. A critical element in a terminal station is the circuit breaker.

The circuit breakers protect the transformers and transmission lines from overloading. They

operate automatically in the same way as circuit breakers or fuses operate to protect the

circuits in a normal household electrical system. The circuit breaker senses excessive

current and uses a compressed spring arrangement to open the breaker contacts and cut

off the power flow to the circuit. This protects the electrical equipment from damage

caused by high currents that occur during an electrical fault. The circuit breakers that

operate at 230 kV interrupt currents up to 4,000 Amperes.

In the Island Interconnected System, Hydro owns and operates 78 - 230kV circuit breakers

of which 53 are air blast circuit breakers. Figure 1 shows a picture of a typical 230 kV air

blast circuit breaker in use on the Island Interconnected System.

When the Island Interconnected System was originally constructed, the standard

technology for circuit breaker design was air blast technology. As the electrical utility

industry developed, advances in circuit breaker technology changed from air blast

technology to Sulphur Hexafloride (SF 6 ) technology. The main difference in the two

technologies is that air blast circuit breakers use a compressed air system to operate

whereas SF6 circuit breakers use an inert gas. An inert gas is a chemically stable gas that can

be used to extinguish electrical arcing at high temperatures.

Since the mid 1980's, SF6 gas technology has been used. The SF6 gas is contained inside the

sealed chamber of the breaker. This inert gas extinguishes the arc across the breaker

contacts when the circuit is being interrupted. The advancement to SF6 gas means that

breakers can be self contained and do not need a centralized compressed air supply to

operate as required by air blast breakers. Also, SF6 circuit breakers have the ability to


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interrupt larger currents and withstand higher voltages than the air blast circuit breakers.

The utility industry is switching to SF6 technology. The 230 kV circuit breakers that required

replacement on the Hydro system over the last twenty years have been replaced by SF6 gas

breakers.

Figure 1: Typical 230 kV Air Blast Circuit Breaker


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2

PROJECT DESCRIPTION

This project consists of the replacement of the existing 230 kV air blast circuit breaker

L03L06 at the Sunnyside Terminal Station with a new 230 kV SF6 circuit breaker. The scope

of the work involves the following:

• Removal and retirement of the existing breaker

• Purchase and installation of a new breaker

• Supervision of the factory acceptance test of the new breaker

• Construction of a new foundation for the circuit breaker structure

• Installation of new protection equipment and control cables

• Commissioning of the new breaker.


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3

EXISTING SYSTEM

The Sunnyside Terminal Station (Sunnyside) is located just off the Trans Canada Highway

near the junction to the community of Sunnyside. The terminal station is approximately 20

kilometers east of Clarenville. Sunnyside is one of Hydro's major terminal stations. It is the

termination point for the 230 kV transmission lines TL-202 and TL-206 from Bay d'Espoir. It

is the focal point for transmission of power to the Avalon Peninsula. The 230 kV

transmission line TL-203 originates at Sun nyside and transmits power to the Western

Avalon Terminal Station. Also, the 230 kV transmission line TL-207 transmits power from

Sunnyside to the Come By Chance oil refinery. Electrical power to the Burin Peninsula is

supplied from the Sunnyside Terminal Station via 138 kV transmission lines TL-212 and TL-

219. Also, Sunnyside supplies power to Clarenville and surrounding area via Newfoundland

Power's transmission system. Figure 1 shows part of the Island Interconnected System and

indicates the location of Sunnyside.

Figure 2: Portion of the Island Interconnected System showing Sunnyside

At Sunnyside, there are five 230 kV air blast circuit breakers. L03L06 is a 230 kV circuit

breaker used as part of the protection scheme at the terminal station for transmission lines

M MILTON

CLARENVILLE

\


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TL-203 and TL-206. This breaker has deteriorated and requires replacement in order for

Sunnyside to continue its vital role as part of the Island Interconnected System. Figure 3

shows some of the deterioration of L03L06.

Figure 3: Corrosion on Breaker 103106 at Sunnyside

3.1 Age of Equipment or System

Circuit breaker L03L06 was manufactured by Brown Boveri and was installed in 1966. It is 44

years old.


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3.2 Major Work and/or Upgrades

An overhaul of this breaker was done in 2000 at a cost of $115,800. A complete re-

lubrication was done on the breaker in 2007 at a cost of $19,500.

3.3 Anticipated Useful Life

The anticipated useful life of a power circuit breaker is 30 years.

3.4 Maintenance History

The maintenance history for Breaker L03L06 is shown in the following Table 1.

Table 1: Maintenance HistoryPreventive

MaintenanceCorrective

MaintenanceTotal

MaintenanceYear ($000) ($000) ($ 000)

2009 0.0 0.0 0.0

2008 0.0 0.0 0.0

2007 0.0 4.7 4.7

2006 0.0 0.0 0.0

2005 0.0 0.0 0.0

3.5 Outage Statistics

Table 2 below lists the previous 5 year average for the performance of 230 kV Air Blast

Breaker. A comparison is made between Hydro's last 5 year performance to the latest CEA

five year average (2003-2007).

There has been one forced outage of the Sunnyside L0306 circuit breaker in the last 15

years. There have been 25 forced outages due to problems with the air blast breakers over


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the last 15 years, throughout the Hydro system.

Table 2: Outage StatisticsNumber of Forced

OutagesFrequency

(per a) 1

Unavailability

(percent) 2

230 kV Air-Blast Breakers(2004-2008)

8 0.030 0.002

CEA 230 kV Air-BlastBreakers (2003-2007)

269 0.100 0.074

1 Frequency (per a) is the number of failures per year.2 Unavailability is the percent of time per year the unit is unavailable.

3.6 Industry Experience

Through consultations with other Canadian utilities, Hydro has confirmed that the 230 kV

air blast circuit breakers of other utilities present similar operational problems as those on

the Hydro system. Such problems are corrosion, leaking seals, porcelain failures,

malfunctioning valves and unreliable controls. These operational problems begin to occur

when the breakers have reached between 20 and 30 years of service.

In addition, Hydro consulted with the manufacturer, Asea Brown Boveri who confirmed the

existence of the above mentioned problems are typical among utilities using these

breakers. Other utilities are either replacing or upgrading the air blast circuit breakers.

3.7 Maintenance or Support Arrangements

Normal operation and maintenance work is performed by Hydro Operations personnel.

3.8 Vendor Recommendations

The vendor, Asea Brown Boveri, recommends replacing the breaker because of the

condition of the tank. If the tank was in a better condition the breaker could be upgraded.

Newfoundland and Labrador Hydra

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3.9 Availability of Replacement Parts

Replacement parts for the existing breaker are generally readily available.

3.10 Safety Performance

Regular maintenance inspections of the circuit breaker indicate that the compressed air

tanks no longer meet current safety codes. The minimum tank wall thickness for this type of

breaker under ASME Section VIII Division 1, UG-27 is 3.84 mm. The minimum measured

thickness of the tank wall is 2.94 mm.

3.11 Environmental Performance

There are no specific environmental issues regarding the air blast breakers.

3.12 Operating Regime

Circuit breaker L03L06 is in continuous operation.


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4

JUSTIFICATION

This project is justified on the requirement to replace failing or deteriorated infrastructure

in order for Hydro to provide safe, reliable electrical service. Because of corrosion, the tank

walls for circuit breaker L03L06 are not up to industry standards. This creates the risk of a

tank rupture which is a major safety and reliability concern. Also, the circuit breaker is 44

years old and beyond its anticipated useful life of 30 years. The only practical option is to

replace the breaker.

4.1 Net Present Value

A net present value calculation was not required for this project as there is only one viable

alternative.

4.2 Levelized Cost of Energy

This project does not affect the levelized cost of energy because it does not involve any new

sources of generation.

4.3 Cost Benefit Analysis

A cost benefit analysis is not required because there are no quantifiable benefits.

4.4 Legislative or Regulatory Requirements

There are no legislative and regulatory requirements for this project.


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4.5 Historical Information

Hydro has not replaced any 230 kV circuit breakers within the past five years.

4.6 Forecast Customer Growth

The forecast customer load growth has no affect on this project.

4.7 Energy Efficiency Benefits

There are no energy efficiency benefits associated with this project.

4.8 Losses during Construction

There are no losses during construction associated with this project.

4.9 Status Quo

The status quo is not an option because the circuit breaker has safety and reliability

problems.

4.10 Alternatives

A repair of the corroded sections on the compressed air tank was considered. This was not

possible because the existing tanks are glass lined and any attempt to weld them would

damage the lining and further damage the breaker. As well, any attempt to repair the tanks

would require a complete disassembly and reassembly of the breaker. The labour and

materials costs for this option, plus the outage time required for the work, is expected to

Newfound/and and Labrador Hydro

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exceed the costs for a replacement by approximately $200,000. Because the major

deficiency is in the tanks, it is not cost effective to try to repair the breaker. The most

effective means to correct the problem is to completely replace the breaker.

Hydro's air blast breaker upgrade program which has been ongoing for the last five years

involves upgrade of the interrupters, resistors and capacitors. This type of upgrade is

possible only if the breaker tank is in good condition. If the breaker tanks are damaged or

corroded then the upgrade option is not practical or feasible. Thus, there are no viable

alternatives to correcting the problem described in this proposal other than to replace the

breaker completely.


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5

CONCLUSION

This project is necessary to address the reliability and safety concerns identified on Breaker

L03L06 in the Sunnyside Terminal Station. Maintenance inspections have shown that the

compressed air tank on the breaker is corroded and the tank walls no longer meet industry

standards. Because of the corrosion there is a risk of the tank rupturing and causing a safety

hazard. Repair of the breaker is not practical or feasible. The only viable alternative is a

complete replacement of the breaker.

5.1 Budget Estimate

The budget estimate for this project is shown in Table 3.

Table 3: Budget EstimateProject Cost:($ x1,000) 2011 2012 Beyond Total

Material Supply 0.0 225.0 0.0 225.0

Labour 32.8 165.6 0.0 198.4

Consultant 0.0 0.0 0.0 0.0

Contract Work 5.0 55.0 0.0 60.0

Other Direct Costs 0.0 30.5 0.0 30.5

O/H, AFUDC & Escln. 3.5 62.6 0.0 66.1

Contingency 0.0 51.4 0.0 51.4

TOTAL 41.3 590.1 0.0 631.4


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5.2 Project Schedule

The project schedule is shown in Table 4.

Table 4: Project Schedule

Activity Milestone

Project Start April 2011

Initial Planning and Equipment Tendering August 2011

Equipment Delivery May 2012

Equipment Installation July 2012

Commissioning July 2012

Project In Service August 2012

Project Completion and Close Out December 2012


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Documents

REPLACE 230 KV CIRCUIT BREAKER - Public Utilities Board€¦ · Circuit breaker L03L06 was manufactured by Brown Boveri and was installed in 1966. It is 44 years old. Newfoundland