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How to express the formula of speed s of three-phase asynchronous motor?
Slip rate of three-phase asynchronous motor s = (synchronous speed - rated speed) △ synchronous speed × 100%
15 ~ 18kw three-phase asynchronous motor to make a double interlocking positive and reverse circuit
AC contactor, thermal relay and fuse
Double interlock adopts the circuit of button interlock and contactor interlock at the same time, which is called Double interlock
40A for AC contactor (slightly larger than rated current)
32a-40a (rated current) for thermal relay
100A for fuse (1.5 ~ 2.5 times of rated current)
Symmetrical three-phase AC circuit formula: I = P / root 3 × u × cos φ
What does it mean to divide by root 3?
U stands for line voltage, which is √ 3 times of phase voltage U '
Three phase total power
P
=3U'Icosφ
=√3(√3U')Icosφ
=√3UIcosφ
∴I=P/(√3Ucosφ)
Three phase motor current calculation formula I = P / 1.732/u/cos Φ, what is 1.732? Why is there a 1.732
Power calculation formula of three-phase motor P = 1.732 * u * I * cos Φ
The current calculation formula I = P / 1.732/u/cos Φ is obtained
What is 1.732? Why is there a 1.732
Does 2 have anything to do with triangle or star connection
732 is actually an approximate value of root sign 3, that is: √ 3
As for how to get the root 3, the phase difference is obtained through trigonometric function equation
The triangle connection method has this relationship, and it is precisely because of the triangle connection method that it has the calculation property of trigonometric function
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