in amperes A
Resistance R = V / I = P / I2 = V2 / P in ohms Ω
Power P = V × I = R × I2 = V2 / R in watts W
Electrical Potential – Ohm’s Law
Ohm’s law can be expressed as:
V = R I (1a)
V = P / I (1b)
V = (P R)1/2 (1c)
Electric Current – Ohm’s Law
I = V / R (2a)
I = P / V (2b)
I = (P / R)1/2 (2c)
Electric Resistance – Ohm’s Law
R = V / I (3a)
R = V2/ P (3b)
R = P / I2 (3c)
Electric Power
P = V I (4a)
P = R I2 (4b)
P = V2/ R (4c)
where
P = power (watts, W), V = voltage (volts, V)
I = current (amperes, A), R = resistance (ohms, Ω)
Advertentie :
Electric Energy :Electric energy is power multiplied time, or
W = P t (5)
where
W = energy (Ws, J), t = time (s)
Electrical Motors : Electrical Motor Efficiency
μ = 746 Php / Pinput_w (6)
where
μ = efficiency
Php = output horsepower (hp)
Pinput_w = input electrical power (watts)
or alternatively
μ = 746 Php / (1.732 V I PF) (6b)
Electrical Motor – Power
P3-phase = (V I PF 1.732) / 1,000 (7)
where
P3-phase = electrical power 3-phase motor (kW)
PF = power factor electrical motor
Electrical Motor – Amps
I3-phase = (746 Php) / (1.732 V μ PF) (7)
where
I3-phase = electrical current 3-phase motor (amps)
PF = power factor electrical motor
Electrical measurements
Quantity
Name
Definition
frequency f
hertz (Hz)
1/s
force F
newton (N)
kg•m/s²
pressure p
pascal (Pa) = N/m²
kg/m•s²
energy E
work joule (J) = N•m
kg•m²/s²
power P
watt (W) = J/s
kg•m²/s³
electric charge Q
coulomb (C) = A•s
A•s
voltage V
volt (V)= W/A
kg•m²/A•s³
current I
ampere (A) = Q/s
A
capacitance C
farad (F) = C/V = A•s/V = s/Ω
A²•s4/kg•m²
