Static Electricity 2000 Edition


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NFPA 77 Static Electricity

3.1.13 Nonconductive.
The ability to resist the flow of an
electric charge.
3.1.14 Nonconductor.
A material or object that resists the
flow of an electric charge through it.
3.1.15 Semiconductive.
Possessing a conductivity between
10
2
pS/m and 10
4
pS/m or a resistivity between 10
8
Ω-m and
10
10
Ω-m.
3.1.16 Static Electric Discharge.
A release of static electricity
in the form of a spark, corona discharge, brush discharge, or


FUNDAMENTALS OF STATIC ELECTRICITY
77
–5
2000 Edition
propagating brush discharge that might be capable of causing
ignition under appropriate circumstances.
3.1.17 Static Electricity.
An electric charge that is significant
only for the effects of its electrical field component and that
manifests no significant magnetic field component.
3.2 Symbols and Units.
The following symbols are used
throughout this recommended practice and are defined as
follows.
A = ampere (coulombs per second). Electric current; the
quantity of charge passing per second through a given point.
C = capacitance (farads)
d = diameter (meters)
e = 2.718 [base of Napierian (natural) logarithms]
E = V/m = electric field strength (volts per meter)
ε = dielectric constant of a material
ε
0
= 8.845 
× 10
−12
farads per meter (electrical permittivity of
a vacuum)
εε
0
= electrical permittivity of a material (farads per meter)
I
s
= streaming current (amperes)
κ = liquid conductivity (picosiemens per meter)
µ = ion mobility (square meters per volt-second)
µm = micrometers (microns) = 10
−6
meters
Ω-m = electrical resistivity (ohm-meter)
P = pressure (millimeters of mercury)
Q = quantity of electrical charge (coulombs)
R = electrical resistance (ohms)
ρ = volume resistivity (ohm-meters)
S = electrical conductance (siemens)
t = elapsed time (seconds)
τ = charge relaxation time constant (seconds)
v = flow velocity (meters per second)
V = electrical potential difference (volts)
W = energy or work done (joules)

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