SIGNS AND SYMBOLS

The following signs, symbols and abbreviations are almost universally employed in descriptive and technical works on electrical subjects.

Although, in the arrangement of the Guides, the direct current and alternating current matter has been kept separate, it is perhaps advisable in the case of signs and symbols, to combine those relating to the alternating current with the direct current and other symbols, making a single table, rather than have them scattered throughout the work.

1. Fundamental.

l,Length. cm. = centimeter; in., or ″ = inch, ft. or ′ = foot.

M,Mass. gr. = mass of 1 gramme kg. = 1 kilogramme.

T, t,Time, s = second.

2. Derived Geometric.

S, s,Surface.

E,Volume.

α, β,Angle.

3. Derived Mechanical.

v,Velocity.

ω,Angular velocity.

r,Momentum.

a,Acceleration.

g,Acceleration due to gravity = 32.2 feet per second.

F, f,Force.

W,Work.

P,Power.

δ,Dyne.

ε,Ergs,

ft. lb.,Foot pound.

H.P., h.p.Horse power.

I.H.P.,Indicated horse power.

B.H.P.,Brake horse power.

E.H.P.,Electrical horse power.

J,Joule’s equivalent.

p,Pressure.

K,Moment of inertia.

4. Derived Electrostatic.

e,Pressure difference.

i,Current.

r,Resistance.

q,Quantity.

c,Capacity.

sc,Specific inductive capacity.

5. Derived Magnetic.

m,Strength of pole.

,Intensity of magnetization.

,Magnetic moment.

,Horizontal intensity of earth’s magnetism.

,Field intensity.

φ,Magnetic flux.

,Magnetic flux density or magnetic induction.

,Magnetizing force.

,Magnetomotive force.

,Reluctance, magnetic resistance.

μ,Magnetic permeability.

κ,Magnetic susceptibility.

ν,Reluctivity (specific magnetic resistance).

6. Derived Electromagnetic.

R,Resistance, ohm.

O,do, megohm.

E,Volt, pressure.

E_imImpressed pressure.

E_a, E_oActive pressure; ohmic drop.

E_vVirtual pressure.

E_maxMaximum pressure.

E_avAverage pressure.

E_efEffective pressure.

E_iInductance pressure.

E_cCapacity pressure.

U,Difference of pressure, volt.

I,Intensity of current, ampere.

I_imImpressed current.

I_aActive current.

I_vVirtual current.

I_maxMaximum current.

I_avAverage current.

I_efEffective current.

Q,Quantity of electricity, ampere-hour; coulomb.

C,Capacity, farad.

W,Electric energy, watt-hour; Joule.

P,Electric power, watt; kilowatt.

p,Resistivity (specific resistance) ohm centimeter.

G,Conductance, mho.

γ,Conductivity (specific conductivity).

Y,Admittance, mho.

Z,Impedance, ohm.

X,Reactance, ohm.

X_iInductance reactance.

X_cCapacity reactance.

B,Susceptance, mho.

L,Inductance (coefficient of Induction), henry.

v,Ratio of electromagnetic to electrostatic unit of quantity = 3×10¹⁰ centimeters per second approximately.

7. Symbols in general use.

D,Diameter.

r,Radius.

t,Temperature.

θ,Deflection of galvanometer needle.

N, n,Number of anything.

π,Circumference ÷ diameter = 3.141592.

ω,2πf = 6.2831 × frequency, in alternating current.

~, f,Frequency, periodicity, cycles per second.

φ,Phase angle.

G,Galvanometer.

S,Shunt.

N, n,North pole of a magnet.

S, s,South pole of a magnet.

A.C.Alternating current.

D.C.Direct current.

P.D.Pressure difference.

P.F.Power factor.

C.G.S.Centimeter, Gramme, Second system.

B.&S.Brown & Sharpe wire gauge.

B.W.G.Birmingham wire gauge.

R.p.m.Revolutions per minute.

C.P.Candle power.

,Incandescent lamp.

,Arc lamp.

, OR ,Condenser.

,Battery of cells.

,Dynamo, or direct current motor.

,Alternator, or alternating current motor.

,Converter.

,Static transformer.

,Inductive resistance.

,Non-inductive resistance.