Best Practice Reducing The Risk of Arc Flash Cross Over

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1 Best Practice Reducing The Risk of Arc Flash Cross Over 1

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3 Electrical Systems Are Critical 3

4 Why Do We Complete Electrical Maintenance Energized?? 4

5 Which Bulb Is Not Working?? 5

6 Functioning Correctly Failed System: Does not Work Failed System: Too Bright Functioning Correctly Failed System: Too Dim 6

7 Traditional Electrical Maintenance practices Traditional Maintenance and testing of electrical systems utilize intrusive work practices such as: Tightness / Torque testing Megger / Stress testing Circuit Testing Load Bank Testing Breaker and Isolator Testing Etc These Maintenance Tasks are designed with one outcome in mind: To confirm whether of not the circuits and connections are good and that the system meets its Operational Requirements. THERE IS A BETTER WAY????

8 Electrical Connections must be inspected under load conditions to allow their condition to be validated The Majority of Condition Based Test Equipment Require Energized systems Infrared Scan Measures temperature caused by high resistance connections, load imbalance, etc Ultrasound Scan Records Airborne Emissions at 40 khz to identify Arcing Tracking and Corona. Partial Discharge Identifies cable insulation issues in energized systems of 5kV and above Motor Current Analysis Identifies faulty electrical circuits & components. Can be completed De-energized Ultraviolet Scan Finds Corona issues in energized systems of 5kV and above Visual Inspection Visual identification of system integrity. Can be completed De-energized **NFPA 70B Recommends a Minimum of 40% Load** 8

9 How do we start? CAST 1-9

10 Identify the Components you wish to inspect Cable Connections Bus Bar Connections Isolator or Circuit Breaker Connections 10

11 Good Electrical Connection and Circuit Test Equipment Results Infrared Scan Ultrasound Scan Partial Discharge Motor Current Analysis Ultraviolet Scan Visual Inspection (Voltage Related, Usually used in 5kV Systems or Above) (Voltage Related, Usually used in 5kV Systems or Above) 11

12 Overloaded Electrical Connection and Circuit Test Equipment Results Infrared Scan Ultrasound Scan Partial Discharge Motor Current Analysis Uniform heating of completed Circuit (Voltage Related, Usually used in 5kV Systems or Above) Ultraviolet Scan (Voltage Related, Usually used in 5kV Systems or Above) Visual Inspection In extreme cases we may see heat damage on cables, etc. 12

13 High Resistance Or Loose Electrical Connection Test Equipment Results Infrared Scan Ultrasound Scan Partial Discharge Motor Current Analysis Localized heating at bolted connection May find Arcing or tracking depending on severity of the fault (Voltage Related, Usually used in 5kV Systems or Above) Inspections should show elevated resistance reading in tested circuits. Ultraviolet Scan (Voltage Related, Usually used in 5kV Systems or Above) Visual Inspection In extreme cases we may see heat damage on cables, etc. 13

14 High Resistance Or Loose Cable Lug Connection Test Equipment Results Infrared Scan Ultrasound Scan Partial Discharge Motor Current Analysis Localized heating at Lug/cable connection. May find Arcing or tracking depending on severity of the fault (Voltage Related, Usually used in 5kV Systems or Above) Inspections should show elevated resistance reading in tested circuits. Ultraviolet Scan (Voltage Related, Usually used in 5kV Systems or Above) Visual Inspection 14

15 Partial Discharge or Cable Insulation failure Test Equipment Results Infrared Scan Ultrasound Scan Partial Discharge Motor Current Analysis Depending on severity level this may not produce heat. Should produce corona but is voltage defendant TEV will be present but results are voltage Related, Usually used in 5kV Systems or Above Ultraviolet Scan Corona will be present but results are voltage Related, Usually used in 5kV Systems or Above Visual Inspection In extreme cases the Partial Discharge can be seen as a white residue 15

16 Critical Asset Surveillance Technologies (CAST) CAST 1-16

17 Critical Asset Surveillance Technologies (CAST) Overview: The term CAST refers to a Risk Based, Data Driven 100% Surveillance Repair maintenance model that utilizes condition based monitoring technologies to inspect electrical distribution assets. These surveillance and inspection methods determine the condition of the individual assets or systems being inspected and include but are not limited to: Infrared Thermography Airborne Ultrasound Motor Current Analysis Partial Discharge Testing Power Quality Management Ultraviolet Corona Imaging Vibration Analysis Alignment Testing Oil Analysis Visual Inspections

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19 Common Ways to Interact with Equipment An Electrical Hazard is a state that occurs when exposed parts are present OR when you are interacting with a piece of equipment in such a way that you could be electrocuted or cause an arc flash. Opening or closing doors Removing or replacing a cover Reaching into or leaning into equipment Removing or replacing internal barriers Operating switches or circuit breakers Racking a circuit breaker Using tools or test equipment 19

20 Reducing Maintenance Induced Failures 20

21 Maintenance Inspection Systems 21

22 EMSD Benefit Analysis (IR Window and Ultrasound Ports) 22

23 A Recent Emerson Study on The Effect of Regular, Skilled Preventive Maintenance and Remote Monitoring of Critical Power system Reliability on Mean Time Between Failures (MTBF) showed the following Results: 23

24 The Asset MTBF is increased by 51 times by inspecting once per quarter 24 Source: The Effect of Regular, Skilled preventive Maintenance and Remote Monitoring on Critical Power system Reliability

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