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Voltage drop in direct current with known power value : |
u = 2.L.P / (S.U) [V] |
u = Voltage drop
[V]
U = Voltage [V]
I = Current strength [A]
P = Power [W]
L = Length of cable [m]
S = Cross section of wire [mm²] |
Voltage drop in direct current with known Current strength : |
u = 2.L.I / S
[V] |
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Alternative current monophase |
u =2.L.r.(I.cos f) / U
[V] |
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Alternative current triphase |
u = (3)½.L.r.(I.cos f) / U
[V] |
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Magnetic field produced by a coil of n windings with a current strength I |
H = n.I / L
[A/m] |
n = Number of windings
I = Current strength [A]
L = Length [m] |
Magnetic induction |
B = µo.µr.H [T] |
µo= 4.p.10-7
µr= Magnetic relative permeability of the material |
magnetic flux quantum |
f = B.S.cos a [Wb] |
B = Magnetic induction [T]
S = Area [m²]
a = Angle between B and S |
Electromagnetic force |
F = B.I.L.sin a [N] |
B = Magnetic induction [T]
I = Current strength [A]
L = Length [m]
a = Angle between B and the conductor |
Dynamic force between 2 // conductors |
F = 0,2.I1.I2.d.e [N] |
I1 = Current strength of conductor 1 [A]
I2 = Current strength of conductor 2 [A]
d = Distance where the 2 conductors are // [m]
e = Spacing between the 2 conductors [m] |
Pulsation |
w = 2.p.f [rad/s] |
p = 3.1415
f = Frequency [Hz] |
Frequency |
f = 1 / T [Hz] |
T = Period [s] |
Voltage drop |
U = R.I
[V] |
R = Resistance of the conductor [W]
I = Current strength [A] |
Resistance |
R = r . L / S [W] |
r = Resistivity of the conductor [W.m]
r of cooper at 20°C = 17,24 10-6 [W.m]
L = Length [m]
S = Cross section of the conductor [m²]
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Active Power in triphase |
S = 1,732.U.I
[VA] |
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Active Power in triphase |
P = 1,732.U.I.cos f
[W] |
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Reactive Power in triphase |
Q = 1,732.U.I.sin f
[VAr] |
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Relation between powers |
S2 = P2 + Q2
[VA] |
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Moment |
M = ML+Ma
[Nm]
M = ML+(p/30).J.(Dn/ta)
[Nm] |
M = Motor moment [Nm]
ML = Load moment [Nm]
Ma = Acceleration moment [Nm]
J = Global mass moment inertia [kg m²]
Dn = Differentiel speed [m-1]
P = Motor power [kW]
PL = Load power [kW]
Pa = Acceleration power [kW]
ta = Time of acceleration necessary to go up of the differential speed [s] |
Acceleration moment |
Ma = (p/30).J.(Dn/ta)
[Nm]
Ma = (0,105).J.(Dn/ta)
[Nm] |
Work - Energy |
W = (p2/1800).J.(Dn2).M / (M-ML)
[Nm]
W = J.(Dn2).M / (182,4.(M-ML))
[Nm] |
Total power |
P = PL+Pa
[Nm] |
Acceleration time |
ta = (p/30).J.Dn/(M-ML)
[s]
ta = 0,105.J.Dn/(M-ML)
[s]
ta = p2.J.Dn2/(9.105.(P-PL))
[s]
ta = J.Dn2/(9,12.104.(P-PL))
[s] |
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Impedance |
Z = U / I [W] |
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Impedance of a winding |
Z = L.2.p.f [W]
Z = L.314,16 [W] at 50Hz |
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Impedance of a capacity |
Z = 1 / (C.2.p.f) [W]
Z = 1 / (C.314,16) [W] at 50Hz |
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Synchronizing speed of an asynchrone triphase motor |
ns = 2.60.f / p [r/min]
f = Frequency [Hz]
p = Numbre of pole per phase |
ns ( at 50Hz) |
p |
1500 |
4 |
1000 |
6 |
750 |
8 |
375 |
16 |
250 |
24 |
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Power |
1 HP = 0,73549 kW = 0,74 kW
1 kcal/h = 1,163 W = 1,16 W
1 kcal/h = 4,1868 kJ/h = 4,2 kJ/h |
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Energy |
1 kcal = 4,1868 kJ = 4,2 kJ |
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