/
Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab - PowerPoint Presentation

heartfang
heartfang . @heartfang
Follow
342 views
Uploaded On 2020-06-15

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab - PPT Presentation

Maddie Schoell with the help of Dave Mertz Fermilab Electrical Safety AHJ 2019 Accelerator Safety Workshop 12 September 2019 Outline Brief Review of Incidents Accidental Discharge of Capacitor During HiPot ID: 778151

supply power accelerator safety power supply safety accelerator electrical incidents fermilab 2019 related operations schoell capacitor supplies individual top

Share:

Link:

Embed:

Download Presentation from below link

Download The PPT/PDF document "Recent Electrical Safety Incidents Relat..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.


Presentation Transcript

Slide1

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

Maddie Schoell (with the help of Dave Mertz, Fermilab Electrical Safety AHJ)

2019 Accelerator Safety Workshop

12 September 2019

Slide2

OutlineBrief Review of IncidentsAccidental Discharge of Capacitor During Hi-PotPower Supply Burn After Contact With DosimeterCommon Error Precursors

Special thanks to Dave Mertz, Fermilab’s Electrical Safety AHJ. Dave was the primary investigator for both of these incidents, and helped put these slides together.

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

2

Slide3

Result of vaporized wire.

Accidental Discharge of Capacitor During Hi-Pot – April ‘17

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

3

Slide4

Accidental Discharge of Capacitor During Hi-Pot – April ‘17Individuals were working on two nearly identical power supplies, each with two capacitor banks. After successfully testing one supply a few days earlier, they proceeded to test the second supply. During the test of the second supply, they were only testing one of the two capacitor banks. After successfully completing the test, the technician noticed that a shorting wire (removed earlier in the course of the work, not during these tests) was still removed on the other capacitor bank. Assuming it was not energized, since they weren’t testing it, the technician placed the wire back across the bus bars. The wire vaporized.

Testing on the first power supply was reviewed by the department head, per the procedure. The testing on the second power supply was not.

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

4

Slide5

Accidental Discharge of Capacitor During Hi-Pot – April ‘17Assumed the two power supplies were identical, but it was later discovered that there was a connection present in the second power supply that allowed for the 2

nd

capacitor to be charged by the first, which was not there in the first power supply.

This event had the potential to be fatal, but had a negligible possibility due to the conditions in which it occurred (position of the technician, proximity of the two buses, bare shorting wire)

Error precursors: inadequate work planning (use of procedures, pre-job walkdown, check of work LTA, steps omitted), assumptions, time pressure, imprecise communication

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

5

Slide6

Pulse bank resistor stick (top) and ground stick (bottom).Wiring that caused back feed and charged capacitor.

Accidental Discharge of Capacitor During Hi-Pot – April ‘17

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

6

Slide7

Result of metal pocket dosimeter coming into contact with 480V, causing arc flash event.

Power Supply Burn After Contact With Dosimeter – July ‘19

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

7

Slide8

Power Supply Burn After Contact With Dosimeter – July ‘19Individual was installing cables in a cable tray located on a wall behind a row of power supplies. In order to access the cable tray, the individual used a rolling staircase to access the top of the power supplies and slide across the top of the supplies (~18” gap between the top of the supplies and other equipment on the ceiling). The individual would slide to the cable tray and back, move the stairwell, and repeat the process down the length of the cable tray. (This activity was considered routine by the individual.)

During one instance of sliding back down, the individual’s dosimetry badge and pocket dosimeter, which were clipped to their lanyard around their neck, dropped into a narrow opening in the top of the power supply and made contact with the line-side terminals. This resulted in an arc flash event.

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

8

Slide9

Power Supply Burn After Contact With Dosimeter – July ‘19The lanyard became stuck in this narrow opening, and since it was not a breakaway lanyard the individual was unable to pull back. The individual swept the lanyard and dosimetry out of the opening with his left hand. The dosimetry had ignited, and the individual used their hands to extinguish the flame. The individual then slid off of the power supply and back onto the staircase.

The individual did not receive a shock, but did have first degree burn on their wrist.

Error precursors: inadequate work planning (procedures, pre-job planning, defining scope of work, etc.), time pressure, incomplete understanding of associated hazards, unexpected equipment conditions, dangling objects when performing work.

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

9

Slide10

Power supply for Booster accelerator. Similar power supplies used throughout the Lab.On top of the power supply, the opening is for the line-side terminals. ~100 other power supplies had similar openings (although not always on top).

Power Supply Burn After Contact With Dosimeter – July ‘19

9/12/2019

Schoell |

Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

10

Slide11

Common Error PrecursorsWork Planning LTA Lack of procedures, not using procedures, not performing job walkdown, etc.Time Pressure Sometimes this is self-imposed, or perceived time pressure, rather than enforced by supervisors/management.

Equipment Conditions

Similar equipment assumed to be in similar state, not always the case.

Understanding PPE requirements/restrictions for the work you’re doing AND the area you’re in.

9/12/2019

Schoell | Recent Electrical Safety Incidents Related to Accelerator Operations at Fermilab

11