MV design guide - Schneider Electric

Units
of measure
Names and symbols
of SI units of measure
Name Symbol Dimension SI Unit: Comments
name (symbol)
and other units
Magnitude: mechanical
force F L M T -2 Newton 1 N = 1 m.kg/s 2
weight G, (P, W)
moment of the force M, T L 2 M T -2 Newton-metre (N.m) N.m and not m.N to avoid any confusion
with the millinewton
surface tension γ, σ M T -2 Newton per metre (N/m) 1 N/m = 1 J/m 2
work W L 2 M T -2 Joule (J) 1 J : 1 N.m = 1 W.s
energy E L 2 M T -2 Joule (J) Watthour (Wh) : 1 Wh = 3.6 • 10 3 J
(used in determining electrical
consumption)
power P L 2 M T -3 Watt (W) 1 W = 1 J/s
pressure σ, τ L -1 M T -2 Pascal (Pa) 1 Pa = 1 N/m 2
p
(for the pressure in fluids we use bars
(bar): 1 bar = 10 5 Pa)
dynamic viscosity η, µ L -1 M T -1 Pascal-second (Pa.s) 1 P = 10 -1 Pa.s (P = poise, CGS unit)
kinetic viscosity ν L 2 T -1 metre squared per second (m 2 /s) 1 St = 10 -4 m 2 /s (St = stokes, CGS unit)
quantity of movement p L M T -1 kilogramme-metre per second p = mv
(kg.m/s)
Magnitude: electricity
current I I Ampere (A)
electrical charge Q TI Coulomb (C) 1 C = 1 A.s
electrical potential V L 2 M T -3 I -1 Volt (V) 1 V = 1 W/A
electrical field E L M T -3 I -1 Volt per metre (V/m)
electrical resistance R L 2 M T -3 I -2 Ohm (Ω) 1 Ω = 1 V/A
electrical conductivity G L -2 M -1 T 3 I 2 Siemens (S) 1 S = 1 A/V = 1Ω -1
electrical capacitance C L -2 M -1 T 4 I 2 Farad (F) 1 F = 1 C/V
electrical inductance L L 2 M T -2 I -2 Henry (H) 1 H = 1 Wb/A
Magnitude: electricity, magnetism
magnetic induction B M T -2 I -1 Tesla (T) 1 T = 1 Wb/m 2
magnetic induction flux Φ L 2 M T -2 I -1 Weber (Wb) 1 Wb = 1 V.s
magnetisation Hi, M L -1 I Ampere per metre (A/m)
magnetic field H L -1 I Ampere per metre (A/m)
magneto-motive force F, Fm I Ampere (A)
resistivity ρ L 3 M T -3 I -2 Ohm-metre (Ω.m) 1 µΩ.cm 2 /cm = 10 -8 Ω.m
conductivity γ L -3 M -1 T 3 I 2 Siemens per metre (S/m)
permittivity ε L -3 M -1 T 4 I 2 Farad per metre (F/m)
active P L 2 M T -3 Watt (W) 1 W = 1 J/s
apparent power S L 2 M T -3 Voltampere (VA)
reactive power Q L 2 M T -3 var (var) 1 var = 1 W
Magnitude: thermal
thermodynamic T θ Kelvin (K) Kelvin and not degree Kelvin or °Kelvin
temperature
temperature Celsius t, θ θ degree Celsius (°C) t = T - 273.15 K
energy E L 2 M T -2 Joule (J)
heat capacity C L 2 M T -2 θ -1 Joule per Kelvin (J/K)
entropy S L 2 M T -2 θ -1 Joule per Kelvin (J/K)
specific heat c L 2 T -2 θ -1 Watt per kilogramme-Kelvin
capacity
(J/(kg.K))
thermal conductivity λ L M T -3 θ -1 Watt per metre-Kelvin (W/(m.K))
quantity of heat Q L 2 M T -2 Joule (J)
thermal flux Φ L 2 M T -3 Watt (W) 1 W = 1 J/s
thermal power P L 2 M T -3 Watt (W)
coefficient of thermal hr M T -3 θ -1 Watt per metre squared-Kelvin
radiation
(W/(m 2 .K))
68 Merlin Gerin MV design guide Schneider Electric