Motovario M Serie Manual De Instrucciones página 20

M
Motori elettrici / Electric motors / Moteurs électriques / Elektromotoren / Motores eléctricos / 电动机
Formule relative al funzionamento dei motori / Formulas related to motor operation / Formules relatives au fonctionnement des moteurs /
Formeln zur Funktion der Motoren / Fórmulas relativas al funcionamiento de los motores /
MEASUREMENT
nominal voltage
nominal current
starting current
nominal torque
starting torque
sag torque
maximum torque
synchronous speed
nominal speed
creep
nominal creep
mechanical power delivery
nominal power delivery
power factor
nominal power factor
active absorbed
electrical power
reactive electrical power
absorbed
reactive power furnished by an
array of capacitors
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SYMBOLS AND
UNITS OF ME-
ASUREMENT
V [V] concatenated voltage at the machine's terminals at nominal power
n
I [A] current absorbed by the motor at nominal power
n
I [A] line current absorbed by the motor at nominal starting voltage and frequency
s
M [Nm] torque delivered by motor shaft at nominal conditions
n
M [Nm] torque delivered by the motor shaft at starting
s
minimum asynchronous torque under normal running conditions developed by the motor at speeds from zero to maximum
M [Nm] torque speed; this definition does not apply to asynchronous motors whose torque decreases continuously as speed
i
increases
maximum torque under normal running conditions developed by the motor without a sudden drop in speed; this definition
does not apply to asynchronous motors whose torque decreases continuously as speed increases
Mmax
M [Nm]
max
synchronous motor shaft speed under no load; the following relations apply:
n = 120·f / p [rpm]
s n
where: fn = nominal power supply frequency [Hz]
p = number of motor poles
it follows that:
[rad/s]
w
s
n [rpm]
s
n [rpm]
motor shaft speed in nominal conditions at nominal power
n
[rad/s]
w
n
ratio between the deviation of the shaft speed relative to the synchronous speed and the synchronous speed itself; normally
s
declared as a percentage:
s
n s = (w - w) / w ·100
s s
s = (w - w ) / w ·100
n s n s
numerical value of mechanical power delivered to the shaft; the relation between power, torque and speed is:
P [W]
P = T ·w
[W] [Nm] [rad/s]
P [W] numerical value of the mechanical power delivered to the shaft at nominal conditions P
n
cosw
cosine of the phase angle between the voltage and current, a function of the load characteristics
cosw
n
numerical value of the active electrical power absorbed from the mains; the following relations apply:
P [W] three-phase system
a
single-phase system
numerical value of the reactive electrical power absorbed from the mains; the following relations apply:
Q [VAr] three-phase system
a
single-phase system
numerical value of the reactive electrical power furnished by an array of capacitors of capacity C [mF], for three-phase
Q [VAr]
c systems: Q =√3V
c
DESCRIPTION
Ms
Mi
Mn
ws = 4p·f / p [rad/s] ws = n / 9.55 [rad/s]
n s
poles rpm at 50Hz
2
4
6
8
Pa [W] = √3V[V]I[A]cosw
Pa [W] = V[V]I[A]cosw
Q = √3V I sinw
a [W] [V] [A]
Q = V I sinw
a [W] [V] [A]
C 2pf
2
[V] [mF] n [Hz]
关于电动机操作准则
load
rpm
rpm at 60Hz
3000
1500
1000
750
= T ·w
n (W) n [Nm]
3600
1800
1200
900
n [rad/s]