DGUV Information 203-078 - Thermal hazards from electric fault arc Guide to the ...

Online-Shop für Schriften

Jetzt bei uns im Shop bestellen

Jetzt bestellen
Abschnitt 2 , 2 Definitions
Abschnitt 2
Thermal hazards from electric fault arc Guide to the selection of personal protective equipment for electrical work (bisher: BGI/GUV-I 5188 E)
Titel: Thermal hazards from electric fault arc Guide to the selection of personal protective equipment for electrical work (bisher: BGI/GUV-I 5188 E)
Normgeber: Bund
Amtliche Abkürzung: DGUV Information 203-078
Gliederungs-Nr.: [keine Angabe]
Normtyp: Satzung

Abschnitt 2 – 2 Definitions

Personal protective equipment against the thermal effects of an electric fault arc (PPEgS)
Personal protective equipment against the thermal effects of an electric fault arc applies to any medium meant to be worn or held by a person for protection against the thermal hazards associated with electric fault arcs.

Work
Any form of electrotechnical or non-electrotechnical activity where the potential for electrical hazard exists.

Live working
Any activity, by which a person, either physically or through the use tooling, equipment or devices, knowingly comes in contact with or enters a danger zone associated with live components, (from DIN VDE 0105-100, 3.4.4)

Work performed in the vicinity of live components
Any activity, by which a person, either physically or through the use of tooling, equipment or devices, knowingly enters a vicinity zone without entering the danger zone (from DIN VDE 0105-100, 3.4.5).

Working distance a
The distance between the electric arc and a person's body (torso), that is effective during activity in the working environment being considered.

NOTE:
Working distance is expressed in mm.

Equivalent arc energy W LBä
Equivalent arc energy W LBä resulting from the test level W LBP at a precise working distance a and transmission factor k T.

NOTE:
PPE protection level is expressed in kJ or kWs.

Normalised arc power k P
Relationship of electric arc power to the short-circuit power in the electrical network at the fault location.

Direct exposure incident energy E i0
Heat energy emanating directly from the electric fault arc per unit of affected area.

NOTE:
Direct incident energy is expressed in kJ/m 2 or kWs/m 2 (cal/cm 2 ) 1) .

Transmitted incident energy E it
Incident energy that penetrates PPE when exposed to electric arcing; a portion of the released incident energy.

NOTE:
Transmitted incident energy is expressed in kJ/m 2 or kWs/m 2 (cal/cm 2 ) 1) .

Incident energy E i
Heat energy (total heat) affecting a unit of area as a result of an electric arc.

NOTE:
Incident energy is expressed in kJ/m 2 or kWs/m 2 (cal/cm 2 ) 1) .

Electrical system
Overall electric installations and equipment for producing, transmitting, converting, distributing and utilizing electrical energy.

Electrode gap d
Distance between the arc electrodes

NOTE:
Electrode gap is expressed in mm.

Duration of exposure
Period of exposure to electric fault arc energy in time.

NOTE 1:
Duration of exposure is expressed in s.

NOTE 2:
Exposure duration is normally significantly longer than arc duration.

Short-circuit duration
Period of the short-circuit in time.

NOTE:
Duration of short-circuiting is expressed in s.

Arc duration
Period of the arc flash in time

NOTE:
Duration of arcing is expressed in s.

Arc energy W arc
Electrical energy that causes and is converted into an arc flash; the sum (integral) of the product of the instantaneous values of arc voltage and arc current, as well as the time differential, determine the duration of arcing.

NOTE:
Electric arc energy is expressed in kJ or kWs.

Arc short-circuit current I kLB
Current actually flowing at the fault location throughout the duration of arcing (due to the arc flash); determined as the average effective value over the duration of the short-circuit.

NOTE:
Electric arc short-circuit current is expressed in kA.

Arc current I arc
Current actually flowing in the test circuit during the arc duration (through the arc flash); determined as the average effective value over the duration of arcing. [VDE 0682-306-1-2]

NOTE 1:
Electric arc current is expressed in kA.

NOTE 2:
Electric arc current flowing throughout the duration of arcing is subject to stochastic time variations due to nonlinear arc impedance.

Material
Textile fabrics or other materials used to produce single or multilayer PPE.

Prospective short-circuit current
Anticipated current that flows when the impedance at the fault location is negligible (electrical supply short-circuit). [VDE 0682-306-1-2]

NOTE 1:
Prospective short-circuit current is expressed in kA.

NOTE 2:
There is a general difference between the actual electric arc current and the prospective short-circuit current. The actual electric arc current flowing throughout the duration of arcing is lower and fluctuates due to the nonlinear arc impedance that varies stochastically over time.

Test level W LBP
Electric arc energy set as part of the Box test (according to VDE 0682-306-1-2) for either of the two electric fault arc test categories and leading to a direct incident energy E i0P.

NOTE:
Electric arc energy is expressed in kJ or kWs.

Test current I arc, class
Prospective short-circuit current in the electrical test current circuit (anticipated current) used for setting a test category in the Box test method; effective value (symmetrical a. c. component).

NOTE:
Test current is expressed in kA.

R/X ratio
Relationship of the resistance to the inductive reactance of a short-circuited electrical circuit.

PPE protection level
Protection level of the PPE resulting from the test level WLBP at a fixed working distance a and transmission factor k T.

NOTE:
Equivalent arc energy is expressed in kJ or kWs.

Stoll curve
Correlation between thermal incident energy and exposure time derived from data related to the tolerance behaviour of human skin when exposed to heat; specifies the limits for the occurrence of second-degree skin burns.

Current limiting factor k B
Relationship between the actual electric arc short-circuit current and the prospective short-circuit current.

Fault arc
An independent electric discharge due to a faulty connection between components of different potential in electric power equipment.

NOTE:
Electric fault arcing in the context of the information herein is considered to be an undesirable faulty occurrence caused by short-circuiting.

Fault arc protection classes
Categories of protective properties of the PPE against the thermal effects of an electric fault arc as tested through Box test procedures (according to VDE 0682-306-1-2). The classes are distinguished by test energy levels.

Transmission factor k T
Factor describing the spatial propagation of the thermal impact of an electric arc on the working environment. It is determined by the geometric relationships between the equipment at the workplace.

Transmission and exposure conditions
Totality of the influences on the heat transfer associated with an electric fault arc.

Symbols and units

a Working distancemm
d Electrode gapmm
E i Incident energykJ/m2 or kW s/m2
E i0 Direct exposure incident energykJ/m2 or kW s/m2 (cal/cm2)
I arc Electric arc currentkA
I arc, class Test currentkA
I kLB Electric arc short-circuit currentkA
k B Current limiting factor 
k P Normalised arc power 
k T Transmission factor 
t Times
W arc Arc energykJ, kWs
W LBä Equivalent arc energy, protection levelkJ or kWs
W LBP Test levelkJ or kWs
1)

Correlation:
1 cal/cm2 = 41,868 kJ/m2, 1 kJ/m2 = 0,023 885 cal/cm2.