- David Stonebridge Roadshow October 2013

L.V/ MV Switchgear Safety Hazards
Passive & Active Arc Fault protection
© ABB G...
LV/MV Switchgear
Safety Hazards


The new Work Health & Safety (WH&S) acts and codes of
practices makes the person conduc...
LV/MV Switchgear- Safety Hazards
IEC 61439 ( AS/NZS 3439) IEC62271-200


The primary focus of the Standard has been to pr...
LV/MV Switchgear
Safety Hazards- Summary


Ageing switchgear is a major risk of an arcing faults





Sluggish old bre...
Arc Fault Behaviour
Summary


There are controlled Arcs & then there are Fault Arcs


High impedance Arcing Faults



I...
Safety Strategy
US Regulations- IEEE1584 & NFPA 70E


The calculated Arc Flash Data is used to develop
strategies to mini...
LV Switchgear – Arc Flash Requirements
IEEE1584 & NFPA 70E

Non IAC LV switchgear

IAC LV Switchgear



The US regulation...
LV/MV Switchgear
Safety Strategy Summary


TOP Safety Strategy (Technical - Organisational - Personal)
Risk

Personal

Ac...
Arc Fault Protection
IAC Internal Arc Fault Testing




1996 LV IEC 61641 IAC
guidelines



2001 US ANSI IEE C37 IAC
gu...
Internal Arc Fault Testing
Summary




| Slide 11

Testing on the load side of the outgoing functional SCPD
only can onl...
Active Arc Fault Protection Options

1. Short-circuit

protection on the LV switchboard
incoming supply.
AS/NZS 3000:2007 ...
Active Arc Protection Devices
Arc Monitors




TVOC-2 Monitor mounted on a
compartment door can be
used to check to see ...
Active Arc Protection Devices
Arc Monitors Plus UFES




The earthing device short
circuits the bus eliminating
the arc ...
Arc Fault Protection
Safety by Design


Active protection devices, in comparison to passive
protection, are more suscepti...
ABB switchgear safety hazards passive & active arc fault protection by David Stonebridge
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ABB switchgear safety hazards passive & active arc fault protection by David Stonebridge

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ABB switchgear safety hazards passive & active arc fault protection by David Stonebridge

  1. 1. - David Stonebridge Roadshow October 2013 L.V/ MV Switchgear Safety Hazards Passive & Active Arc Fault protection © ABB Group November 4, 2013 | Slide 1
  2. 2. LV/MV Switchgear Safety Hazards  The new Work Health & Safety (WH&S) acts and codes of practices makes the person conducting the business or undertaking (PCBU) & the worker responsible for maintaining safety in the work place.  They need to be aware of the Safety Hazards in LV/MV Switchgear and develop a safe systems of work. Type tested switchgear   2 trained electricians © ABB Group Month DD, Year What are the primary Safety Hazards | Slide 2 Contact with live parts  Arc Flash & Fire
  3. 3. LV/MV Switchgear- Safety Hazards IEC 61439 ( AS/NZS 3439) IEC62271-200  The primary focus of the Standard has been to provide protection again electric shock. To protect against touching “Live Parts” While the standards provides guidance to the purchaser it does not recommend the safety requirements. For example arguable the most important safety requirement for switchgear is internal arc fault containment (IAC), this is not a mandatory requirement of the standard.   © ABB Group Month DD, Year | Slide 3 AS/NZS 3000:2007 states for all LV switchboards with a current rating greater than 800A Arc Fault protection shall be provided Clause 2.5.5 looks at the reduction of internal arcing faults by improving the design of the switchgear with high degrees of insulation and separation . The Australian WH&S regulations & codes of practices and the US NFPA 70E regulations basically are trending towards “No Live Work“ under any circumstance
  4. 4. LV/MV Switchgear Safety Hazards- Summary  Ageing switchgear is a major risk of an arcing faults    Sluggish old breakers. Deterioration of insulation Open door operation. No arc fault containment The US regulations provide the calculation model to determine the incident energy & arc flash boundaries .  PPE does not provide 100% protection against an arc  Arcing faults don’t depend on making contact with “Live Parts”  People take too many risks especially on LV switchgear.    © ABB Group Month DD, Year | Slide 4 Arc Flash is all about Current not Volts The duration of the arc is critical – milliseconds To maintain Safety you must protect the worker from “Arcing Faults” and contact with “Live Parts”
  5. 5. Arc Fault Behaviour Summary  There are controlled Arcs & then there are Fault Arcs  High impedance Arcing Faults  In-Line Arcing Faults  Travelling Arcs  Arcing time is critical to be safe the arc needs to be extinguished in 35 milliseconds. The Arc Pressure is established in 5 to 10 milliseconds  Conventional S/C protection is too slow to protect people and will not detect against an In-Line arcing fault Knowing how an Arc will behave, switchgear can be designed to minimise the risk of arc burn incidents © ABB Group Month DD, Year | Slide 5
  6. 6. Safety Strategy US Regulations- IEEE1584 & NFPA 70E  The calculated Arc Flash Data is used to develop strategies to minimise burn injuries. The strategies include:  The specific rating of PPE (personal protective equipment)  Working de-energised  Applying arc-resistant switchgear - Internal Arc Fault Containment (IAC) (Refer IEEE 1584 2002 Clause 4.1 Analysis Process) IEE1584 stresses that PPE is the last line of defence   | Slide 6 Poor Visibility  © ABB Group Month DD, Year Heat Stress Limited Body & Hand Movement
  7. 7. LV Switchgear – Arc Flash Requirements IEEE1584 & NFPA 70E Non IAC LV switchgear IAC LV Switchgear  The US regulations do not require the use of Arc rated PPE on IAC switchgear when carrying out normal operations.  Refer NFPA 70E-12 Hazard Risk Category 130C)(15)(a)
  8. 8. LV/MV Switchgear Safety Strategy Summary  TOP Safety Strategy (Technical - Organisational - Personal) Risk Personal Action Eliminate the risk Keep distance to the risk Contain the risk Personal protection against the risk PPE ( Cat 3 & above ) is the last option © BU 3101 Low Voltage Systems November 4, 2013 | Slide 9
  9. 9. Arc Fault Protection IAC Internal Arc Fault Testing   1996 LV IEC 61641 IAC guidelines  2001 US ANSI IEE C37 IAC guidelines  2002 LV AS/NZS 3439 IAC guidelines  2003 MV IEC 26771-200 IAC guidelines  | Slide 10 1974 LV AS1136 included IAC guidelines and MV IEC 298 App AA  © ABB Group Month DD, Year 1960’s Testing to BS4070 & Phela guidelines 2013 LV proposed adopting IEC
  10. 10. Internal Arc Fault Testing Summary   | Slide 11 Testing on the load side of the outgoing functional SCPD only can only be regarded as a limited test. The arc fault energy is limited by the SCPD and the tests are limited – What if the arc is initiated on the line side of the SCPD or on the busbars and incomer ? To protect worker the complete switchgear should be IAC tested.  © ABB Group Month DD, Year The IAC tests procedures are only guidelines. The purchaser needs to specify what tests are required ABB has carried out over 400 tests on LV switchgear alone including many tests which are not shown in the IAC guidelines in order to provide the additional information for a customer arc flash risk assessment .
  11. 11. Active Arc Fault Protection Options 1. Short-circuit protection on the LV switchboard incoming supply. AS/NZS 3000:2007 clause 2.5.5.3 looks at limiting the damage to a switchboard due to an internal arcing. 2. Arc detection Systems AS/NZS 3000:2007 clause 2.5.5.3 also look at arc fault protection using arc detectors and warn of the problems of extraneous light sources and discrimination. 3. Arc Detectors in conjunction with an Ultra Fast Earthing Switch (UFES) The NFPA 70E-12 Hazard Risk Category 130C)(15)(a) says for non IAC LV MCC’s up to 65kA where the arc duration is 30ms Arc Rated PPE is not required to carry out normal operations
  12. 12. Active Arc Protection Devices Arc Monitors   TVOC-2 Monitor mounted on a compartment door can be used to check to see what sensor tripped and at what time  | Slide 13 A trip signal is sent to the breaker (Q1) in less than 2.5 milliseconds  © ABB Group Month DD, Year The Arc in compartment A1 is detected by sensor D and transferred by optical fibre to the TVOC-2 Monitor (F11) . Monitor up to 10 detectors 2 extension modules can be added allowing up to 30 detectors
  13. 13. Active Arc Protection Devices Arc Monitors Plus UFES   The earthing device short circuits the bus eliminating the arc voltage, extinguishing the arc in less than 5 milliseconds  | Slide 14 The electronic arc detection system initiates the operation of a high speed earthing switch(UFES).  © ABB Group Month DD, Year The intense light associated with an arc is detected by an arc detector (QRU) The Incoming breaker(CB) trips on instantaneous overcurrent finally clearing of the fault.
  14. 14. Arc Fault Protection Safety by Design  Active protection devices, in comparison to passive protection, are more susceptible to failure owing to the additional electromechanical and electronic devices  The proven way is to prevent the fault arcs from occurring in the first place, eliminate the need to work live and then in the unlikely event of an internal arc contain the arc to that compartment Safety by Design • Withdrawable Design. • All operations behind closed doors • Internal Arc Fault Containment

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