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Find the phase difference of the following two groups of sinusoids and point out their phase relationship 1: U1 = 20sin (314T + pie divided by 6) V, U2 = 40sin (314T pie divided by 3) v 2: I1 = 4sin (314T + pie divided by 2) a, I2 = 8sin (314T pie divided by 2) a
1, pie
2, Pai (inverse)
I want to use frequency converter to convert two 220 V power supplies into three 220 V AC power supplies to drive three 220 V and 50 Hz motors,
I want to convert two 220 V power supplies (household power supply) into three 220 V alternating current (three independent quantities are 110 V) with frequency converter to drive three 220 V and 50 Hz motors. The expert can give me a suggestion
This is 100% no problem. The three-phase independent quantity is 110V, and the phase to phase voltage is 220V. The single-phase inverter is changed from single-phase electricity to three-phase electricity. However, it is suggested that when choosing the inverter, it should be slightly larger than the rated current of the motor. In this way, it can not only prolong the service life of the inverter, but also effectively protect the motor
220 V 50 Hz single phase; 220 V 60 Hz single phase; 220 V 50 Hz three phase, what are the differences
This phase, Hz, basic do not understand, set up three scenarios, hope prawn can patiently explain
1. Packaging equipment, we are according to the 220 V, 50 Hz single-phase circuit, if the guest there is 220 V, 3-phase, then the guest with this what influence?
2. If the customer is 110V 60Hz, and we only add a voltage regulator, the main motor nameplate of the equipment is engraved with 50Hz, what is the impact of the customer using this equipment
3. If the guest is 3-phase, how do we need to change our circuit
1. Hz is the frequency of alternating current, and 50 Hz is common household electricity, such as lighting. 60 Hz is specific industrial electricity, which is widely used in European and American countries
2. If the customer requires three-phase electricity, and you are accompanied by two-phase, then the equipment can not run, such as three-phase 220 V motor, if you install two-phase, the motor can not run, you must use three-phase 380 V electricity to reduce the voltage to 220 v
3. The guest is 110V 60Hz, the equipment motor is 50Hz, it can also be used, but the cost of equipment
4. The last one I can't understand is that the guest is 220v3 phase. Do you want to use two-phase? Or do you have to use single-phase? If you have to use single-phase, you need to find a lead and add a ground wire, and then boost to single-phase 220V
The difference between 50 Hz and 60 Hz
Is there any problem with the use of 50 Hz and 60 Hz at 220-240 v?
In the electrical system, frequency is a very important basic element, not arbitrarily determined
As we all know, the synchronous speed of a 50 Hz two pole generator is 3000 rpm. If the frequency doubles to 100 Hz, the synchronous speed will be 6000 rpm. Such a high speed will bring many problems to the manufacture of the generator, especially the high linear speed of the rotor surface, which will greatly limit the increase of capacity. In addition, from the point of view of use, too high frequency will increase the reactance, For example, taking three-phase motor as an example, its current is greatly reduced, and its output power and torque are also greatly reduced, which is not beneficial
In addition, if using a lower frequency, such as 30 Hz, it will not be conducive to the transformation and transmission of AC
Is it OK to use 220 V and 60 Hz appliances on 50 Hz
It depends on what kind of electrical appliances are. It is not recommended to use electrical appliances that directly use alternating current, such as motors. If the electrical appliances that are used after the external power supply enters the electrical appliances for step-down rectification can be used directly. Note that the step-down here does not refer to the step-down of transformers
I also want to add that the motor mentioned above. In particular, series motor can be used, such as common electric hand drill, electric hammer, etc
Is the household power supply 220 V DC power supply or AC power supply?
How to distinguish DC from AC
Household power supply 220 V is AC power supply
The direction of alternating current (positive and negative) varies with a certain period of time
The direction of direct current does not change
The power of RL Series circuit is 1.2kW when it is connected to 220 V DC power supply, and 0.6kw when it is connected to 220 V, 50 Hz power supply. Try to find its R, L value?
How
Calculation by formula:
R=U²/P=220²/1200=40.3Ω；
I=sqrt(p/r)=3.86A;
|Z|=U/I=57Ω；
L=sqrt(|z|²-R²)/2pi*f=0.128H
How to change the phase difference of the same 220 V AC to 90 ° when the phase difference of three-phase AC is 120?
It is required that the AC frequency in the last two wires is the same, but the phase difference is 90 degrees
Frequency modulation
Why is AF > 1 easier to produce self-excited oscillation in negative feedback amplifier circuit
The condition of self-excited oscillation of negative feedback amplifier is 1 + AF = 0, that is AF = - 1. Why does negative feedback amplifier also produce self-excited oscillation? This is because the so-called negative feedback generally refers to negative feedback at intermediate frequency, but the amplification factor A and feedback coefficient f of amplifier are often functions of frequency
What is the condition of self-excited oscillation in negative feedback amplifier?
The feedback strength AF = 1 (when the amplitude is stable) and the phase shift degree is 180 ℃
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