![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
A fan with a resistance of 4 ohm, working voltage of 220 V, measured working current of 5 A, calculated fan input power, fan thermal power, electric energy conversion machine Energy power
Input power P = UI = 220V * 5A = 1100W
Fan thermal power p '= I * I * r = 5A * 5A * 4 = 100W
The last question is not clear
Knife switch fuse
Many people say that in general circuits, the fuse can only be installed on the live wire, but in home circuits, the live wire and the zero wire behind the knife switch have fuse positions. I think most people have fuses installed on the live wire and the zero wire behind the knife switch, Is this not correct? Is it possible to install a fuse only behind the live wire? And the vacancy on the zero line behind the knife switch should be connected with copper wire?
In the past, it was very popular to install fuses behind the two-wire live wire and the zero wire. It seems that there is one more layer of insurance than the single fuse live wire. In fact, if the zero wire fuse is blown but the fire wire fuse is not blown, it is very unsafe and unsafe! Because at this time, the line is still
RELATED INFORMATIONS
- 1. What is the function of the fuse on the knife switch? 0 - 14 days and 23 hours to the end of the problem A netizen said [knife switch can't protect household appliances at all. General household appliances have their own protection functions (such as over-voltage protection, over-current protection and under voltage protection). As long as they are operated normally, household appliances generally won't break down. The failure of household appliances is generally caused by their own quality problems, aging internal components, wrong operation of users and lightning] If according to this netizen's opinion, I match the fuse tube to the knife switch, its size and thickness? I don't know if this netizen's opinion is reasonable?
- 2. Current, voltage, resistance. Relationship with power /? Current, voltage, resistance. Relationship with power/
- 3. For example, some fans need 12V voltage, but the current is only 0.5A, the power is 6W, some fans only need 5V, but the current is 1.2A Now the question is how to control the voltage and current. Another is how to change the 220 V AC into 5 V output without heating Add 100 points after explanation And then there is the adjustment of the fan gear. It should not use the rheostat to divide the voltage. Is it to directly lower the voltage to make the current smaller? The power smaller? Is it slow? I mean, how do I do it for a fan? The same power can have different voltages and currents. Of course, I hope that the voltage is high and the current is low. Can I make a 220 V voltage with 0.01 a current How does the AC / DC module work
- 4. Is kinetic energy converted into electricity? How is kinetic energy transformed into electrical energy? What is the relationship between them? How is electrical energy transformed into kinetic energy?
- 5. How does the energy consumption braking of motor change the stored mechanical energy into electrical energy
- 6. There is a pump with a flow rate of 1200 cubic meters per hour, a lift of 38 meters and an efficiency of 80%. How to calculate its operating power and what is the calculation formula of pump power
- 7. How to express the formula of speed s of three-phase asynchronous motor?
- 8. Power capacitor current formula, such as 11 / root 3-334-1 capacitor, 11 / root 3 is the rated voltage, 334kvar, the meter measurement is 26.9 micro method current formula 11 divided by root 3 About 6.35, the unit is kV
- 9. Circuit diagram of 220 V single phase to 380 V three phase
- 10. The first meter is 2500 rpm, 220 V, 3a, 50 Hz. Now it has 200 V, 600 W water heater. The meter turns 250 rpm in 10 minutes, Please calculate the actual power of the water heater?
- 11. Check the home circuit. Install the bulb with rated voltage of 220 V to the position of the circuit breaker and remove the circuit breaker. After the switch is closed, the bulb will light normally It can be judged that the a circuit is completely correct There is a short circuit in circuit B Open circuit in C circuit D can't judge if there's a problem Analyze again. Be careful. Good score. Choose d first
- 12. What is the law of series circuit voltage?
- 13. The law of voltage in series circuit and parallel circuit,
- 14. Characteristics of series and parallel current and voltage
- 15. Characteristics of series circuit voltage expression characteristics of parallel circuit voltage expression——
- 16. Why is the voltage at both ends of each branch equal to the supply voltage in parallel circuit?
- 17. The internal resistance of an electric fan is 20 Ω. After connecting with the voltage of 220 V, the electric power consumed during normal operation is 66 W (1) What is the current passing through the electric fan motor during normal operation? (2) what is the power converted into mechanical energy and internal energy when the electric fan is working? What is the efficiency of the motor at this time? (3) if the electric fan blade is stuck and cannot rotate after the power is connected, how much is the current passing through the motor? How much is the electric power and heating power consumed by the motor?
- 18. Is 380V AC contactor coil 380V?
- 19. The power frequency AC voltage of 220 V and 380 V in engineering refers to its maximum value (a), instantaneous value (b), average value (c) and effective value (d)
- 20. University electrician! Under the condition of constant power supply voltage, if the triangle connection of the motor is wrongly connected into a star connection, or vice versa, what are the consequences?