There is a small bulb of ammeter and voltmeter in series circuit Among them, the voltmeter measures the normal light of the small bulb The position of ammeter bulb is changed Write down what's going to happen next

There is a small bulb of ammeter and voltmeter in series circuit Among them, the voltmeter measures the normal light of the small bulb The position of ammeter bulb is changed Write down what's going to happen next

Next: the bulb lights up normally, and the voltmeter reading is zero. Because, in junior high school, the voltmeter is generally set as the ideal state, that is, the resistance of the voltmeter is infinite, which is equivalent to an open circuit, and the resistance of the ammeter is infinitesimal, which is equivalent to a wire. After changing the position, if the resistance of the series circuit is constant, then the current is constant, then the bulb voltage is constant, and the bulb lights up normally

A three-phase asynchronous motor, star connected, power factor 0, 85, efficiency 1, power 20kW, voltage 380V, rated load offline current

Ptotal = P / 0.85
P total = root 3 * u line * I line
20000 / 0.85 = root 3 * 380 * I line
I line = 35.75 a

What is the active power of a circuit when the voltage is 380V, the current is 1000A and the power factor is 0.75
No change?

P=U*I*φ=380*1000*0.75=38000*0.75=28500W;
When φ = 0.95, P = u * I * φ = 38000 * 0.9 = 34200w, the active power increases and the current does not change

The rated capacity of a single-phase 380V welding machine is 10kW, the power factor is 0.35, and the rated voltage is 380V

S=P/cosφ=10/0.35=28.57kVA
I=P/U=28.57/0.38=75.18A