Miklos J OroszSenior Staff Engineer

Schneider Electric

Extending the life of existing switchgear

In an industrial facility, nothing operates without a reliable flow of electricity

With increasing dependence on computers and automated processes, most modern facilities cannot afford downtime

Electrical Systems are Serious Business

Switchgear Reliability and Longevity

Requires two fundamental activities Preventive Maintenance Periodic Updating

Preventive Maintenance

Having a preventive maintenance program in place can, in many cases, double the life of existing switchgear.

According to IEEE, the rate of electrical component failures is three times higher in facilities that do not perform preventative maintenance on their electrical systems.

Contributing factors Mechanical failure (43%)

Loose connections, overheating, load changes/additions

Environmental conditions (17%) Humidity, dirt/dust or corrosive environments May impace the OEM’s recommended maintenance

schedule

Work improperly performed (17%) NFPA 70B 3.3.58 states that equipment maintenance

is to be performed by a qualified person

Inspection Cleaning and lubrication Adjustments Over-current protective device testing Insulation testing Charge/close/trip circuit testing Dielectric testing Time and speed testing

Fundamental Circuit Breaker Maintenance Activities

Circuit Breaker Technology Essentially four types of medium voltage

circuit breakers

Based on the arc quenching medium

Oil Air SF6 Gas Vacuum

Typically are draw-out type

Modernization

Retrofitting is a general term that is used to define any process which allows for modernization and life extension of electrical equipment

Maintaining the core switchgear structure, conduits, cabling and footprint are left intact, which saves time and money

Modern circuit breaker technology have a longer life-cycle helping extend overall switchgear life

Eight Reasons to ModernizeUpgrade Circuit Breaker

Improve ratings Environmental impact and hazards Performance and safety improvements Meet current ANSI Standards Improve reliability Reduce maintenance cost Reduce size and weight Unforeseen cost considerations

Eight Reasons to ModernizeUpgrade Circuit Breaker

1.Improve Ratings Switchgear frame or enclosure, and bussing, are usually higher

rated than the circuit breakers

Circuit breakers can be upgraded at least one class i.e. from 25kA short circuit interrupting capability to 40kA In many cases even higher up to 50kA

Modern vacuum circuit breakers are also faster, most of them have short circuit current interrupting rating of 3 cycles or less

Older circuit breakers have interrupting time of 5 or 8 cycles, or more

Eight Reasons to ModernizeUpgrade Circuit Breaker

2. Environmental impact and hazards Many old design air magnetic circuit breakers used

asbestos based arc chutes

The oil used in oil circuit breakers may contain hazardous chemicals

SF6 gas was recently declared a green house gas

New technology of vacuum interrupters can help resolve environmental concerns

Eight Reasons to ModernizeUpgrade Circuit Breaker

3. Performance and safety improvements Fault current interruption

New circuit breakers are available with higher ratings In most cases, the interruption capacity of the entire

switchgear can be increased with an engineering study and a circuit breaker upgrade or replacement

Arc flash limiting circuit breaker availability Trip unit accuracy and repeatability with new circuit

breakers Power metering, monitoring, and communication

Eight Reasons to ModernizeUpgrade Circuit Breaker

4. Meet current ANSI Standards Vacuum circuit breakers are operating with the

voltage factor K=1 Interrupting capability is not affected by the system voltage

Vacuum circuit breakers with an assigned short circuit current interrupting capability will function at any voltage level without reducing the assigned short circuit interrupting rating

More flexibility for interchangeability of the new circuit breakers

Eight Reasons to ModernizeUpgrade Circuit Breaker

5. Improve Reliability Electromechanical trip interrupting devices on existing

circuit breakers may have reliability issues: Many do not trip at all Those that trip are not repeatable and may be well

outside the time-current coordination parameters

Aging materials reduce equipment reliability due to: Dielectric breakdown of insulating components Degradation of aging mechanical parts

Eight Reasons to ModernizeUpgrade Circuit Breaker

6.Reduce Maintenance cost Older power circuit breakers require extensive periodic

maintenance and overhaul Expensive and time consuming Lengthens outages May require extensive outside support

Many components for existing and older circuit breakers are no longer available Quantity and quality of used or reconditioned parts is

decreasing and unreliable Prices of replacement parts are increasing 

Eight Reasons to ModernizeUpgrade Circuit Breaker

7. Reduce size and weight 30% to 60% weight reduction can be achieved by

using new vacuum technology. Can improve maintenance access and transportability

Eight Reasons to ModernizeUpgrade Circuit Breaker

8. Unforeseen cost considerations Several factors influence the cost when considering upgrades

Cost of new equipment VS. retrofit/ upgraded equipment Plant maintenance cost analysis Additional space requirements Construction cost Installation cost Removal of existing equipment Disposal of existing equipment Labor cost of training maintenance personnel Downtime cost Cost of Production loss

Updated with New Technology

Original air magnetic circuit breaker with asbestos based arc chutes

Direct replacement modern vacuum circuit breaker

Thank You

Miklos J OroszSenior Staff Engineer

Schneider Electric