electrical safety and high energy physics

25
4/11/2005 1 International High Energy Physics Technical Safety Forum Electrical Safety and High Energy Physics Dr. Perry L Anthony SLAC Electrical Safety Officer

Upload: others

Post on 12-Feb-2022

0 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Electrical Safety and High Energy Physics

4/11/20051International High Energy Physics Technical Safety Forum

Electrical Safety and High Energy Physics

Dr. Perry L AnthonySLAC Electrical Safety Officer

Page 2: Electrical Safety and High Energy Physics

4/11/20052International High Energy Physics Technical Safety Forum

Electrical Hazards in High Energy Physics

High Voltage detector componentsGenerally low current, mostly represent a “startle hazard”

High current power suppliesPossible burns from shorting items across terminals

Stored energy Possible burns from shorting, internal damage

Page 3: Electrical Safety and High Energy Physics

4/11/20053International High Energy Physics Technical Safety Forum

What determines the hazard?

VoltageCurrentDurationEnergy

Page 4: Electrical Safety and High Energy Physics

4/11/20054International High Energy Physics Technical Safety Forum

What determines the Damage?

Circuit

Path

Environment

Resistance Waveform Energy

Voltage Current

Duration

DeterminesImmediate

Impact

DamageDone

I = VR

P = I x VE = P x t

Page 5: Electrical Safety and High Energy Physics

4/11/20055International High Energy Physics Technical Safety Forum

Injury from R&D Equipment

burn injury

arc flash

electric shock

reflex

Page 6: Electrical Safety and High Energy Physics

4/11/20056International High Energy Physics Technical Safety Forum

Typical Examples

computer circuits

electroplating supply

computer power supply

photon detector

CRT monitor

magnet lab generator

Page 7: Electrical Safety and High Energy Physics

4/11/20057International High Energy Physics Technical Safety Forum

Results of Electric Injury

Burn from tool across terminals for a low voltage, high current device

Page 8: Electrical Safety and High Energy Physics

4/11/20058International High Energy Physics Technical Safety Forum

Results of Electric Injury (cont.)

High Voltage breakdown of skin with entrance/exit wounds

Page 9: Electrical Safety and High Energy Physics

4/11/20059International High Energy Physics Technical Safety Forum

Results of Electrical Injury (cont).

Arc Flash Burns:

Page 10: Electrical Safety and High Energy Physics

4/11/200510International High Energy Physics Technical Safety Forum

Protecting from hazards

Engineering controlsKeep the hazard isolatedInterlocks

Administrative ControlsPersonnel Protective Equipment (PPE)Procedures (application of Lock Out Tag Out)

Page 11: Electrical Safety and High Energy Physics

4/11/200511International High Energy Physics Technical Safety Forum

When/What protection is necessary?

Codes and Standards specify when/where protection is required:

In the US:OSHANECNFPA-70EDOE Electrical Safety Handbook

Also Facility standards and procedures

Page 12: Electrical Safety and High Energy Physics

4/11/200512International High Energy Physics Technical Safety Forum

US: NFPA-70E Standard for Electrical Safety in the Workplace

Must protect against both electric shock and possible arc flashPreferred method is to de-energize the equipmentSpecial procedures for testing, troubleshooting, voltage measuring, and similar activities on energized partsPermit with special procedures for other activities on energized parts

Page 13: Electrical Safety and High Energy Physics

4/11/200513International High Energy Physics Technical Safety Forum

NFPA-70E: Shock Protection

Triggered when working “on or near” exposed energized parts:

Over 50VOn = tool or body part touchingNear = any activity within the “limited approach boundary” (voltage dependent)

Requires all body parts within the “Prohibited Approach Boundary” to be insulated against the voltage

Page 14: Electrical Safety and High Energy Physics

4/11/200514International High Energy Physics Technical Safety Forum

Limited and Prohibited Approach Boundaries for Electrical Shock

Voltage dependent:Prohibited = point where the voltage could jump the air gapLimited = larger region, activity in this region could result in accidental contactExample:

120V: Limited = 42 inches; Prohibited = contact480V: Limited = 42 inches; Prohibited = 1 inch

Page 15: Electrical Safety and High Energy Physics

4/11/200515International High Energy Physics Technical Safety Forum

Arc Flash Protection Boundary

Boundary set at point where energy of arc may just cause a 2nd degree burn (blistering)Depends on many factors (e.g. current, duration)May be larger than Limited Approach Boundary for Shock

Page 16: Electrical Safety and High Energy Physics

4/11/200516International High Energy Physics Technical Safety Forum

What does that give us?New labels on equipment:

Arc Flash hazard labels

Page 17: Electrical Safety and High Energy Physics

4/11/200517International High Energy Physics Technical Safety Forum

More arc flash labels

Page 18: Electrical Safety and High Energy Physics

4/11/200518International High Energy Physics Technical Safety Forum

Equipment Inspection LabelsAll electrical equipment must be listed for use by a Nationally Recognized Testing Laboratory (NRTL) or other agency certified by the local Authority Having Jurisdiction (AHJ)

Page 19: Electrical Safety and High Energy Physics

4/11/200519International High Energy Physics Technical Safety Forum

Is this enough for the HEP community? NO!

Good for shock hazard.Not enough for burn hazards:

NFPA-70E and IEEE-1584 give formulas for 60 Hz AC systems only!Nothing about capacitor BanksNothing about high current low voltage power suppliesNothing about RF systems

Page 20: Electrical Safety and High Energy Physics

4/11/200520International High Energy Physics Technical Safety Forum

DOE Electrical Safety Handbook

Only 2 out of 11 chapters applicable to HEP:

Chapter 9: Enclosed Electrical/Electronic EquipmentChapter 10: Research and Development

Gives guidelines for constructionLimited guidance for protection

Page 21: Electrical Safety and High Energy Physics

4/11/200521International High Energy Physics Technical Safety Forum

Where does that leave the HEP Community?

Each facility has needed to develop guidance to ensure worker safetyHazards may not be recognizedStandards not uniform

Page 22: Electrical Safety and High Energy Physics

4/11/200522International High Energy Physics Technical Safety Forum

Six US Facilities

Page 23: Electrical Safety and High Energy Physics

4/11/200523International High Energy Physics Technical Safety Forum

Where do we go from here?

Capitalize on the expertise in the HEP community to develop standards for situations and equipment not covered by existing codes (e.g. RF, capacitor banks)Use forums like this one to work towards uniform standards

Page 24: Electrical Safety and High Energy Physics

4/11/200524International High Energy Physics Technical Safety Forum

Initial steps

The DOE Electrical Safety Handbook is a step in this direction. Efforts are underway to establish an international committee under ISA to develop standards for High Energy R&D Electrical Systems.

Page 25: Electrical Safety and High Energy Physics

4/11/200525International High Energy Physics Technical Safety Forum

High-Power Research and Development Electrical Systems Standards Committee

ScopeTo develop standards, recommended practices, technical reports and related information documenting design, fabrication, installation, operation, and maintenance of high power electrical systems, and their associated control, monitoring, safety, and protection systems for national and international research programs in accelerators, pulsed power applications, and high power lasers.

- From the 2005 R&D Electrical Safety Meeting and Workshop held at SLAC March 28-31