What kind of resistance can 108V plus become 72V?

What kind of resistance can 108V plus become 72V? What is current? What is the direction of the current?

Answer: Electric current: refers to the regular operation of free electrons or ions under the action of electric field force, which is called electric current. The direction of the movement of the positive charge is specified as the direction of the current, and the direction of the movement of the free electrons is opposite to the direction of the current.

10. What is mutual inductance?

Answer: The phenomenon of inducing electromotive force in another adjacent circuit due to the change of current in one circuit is called mutual inductance.

11. Accident handling of voltage drop.

Answer: When the bus voltage at all levels is lower than 95% of the rated value, the electrical personnel should immediately adjust the excitation of the generator, increase the reactive load, and keep the voltage within the normal range.

When the bus voltage at all levels is lower than 90% of the rated value, the overload capacity of the generator accident should be used to increase the reactive power maintenance voltage. At the same time, the active load can be appropriately reduced, and the value of the long contact area adjustment can be reported, and the load is adjusted and limited.

If the voltage continues to drop below after the above treatment, the electrical personnel should ask the value chief to disconnect from the system, and then parallel with the system as soon as possible when the system voltage is restored to above.

12. Accident handling of frequency reduction.

Answer: When the system frequency drops to the following, the electrical personnel should immediately report to the value chief, contact the machine and furnace to increase the load of the unit to the maximum possible output, and contact the district adjustment at the same time. When the system frequency drops below 49Hz, in addition to increasing the output, it is also required to eliminate the frequency operation, so that the frequency can be restored to more than 49Hz within 30 minutes, and to be restored to above within a total of one hour.

When the system frequency drops, the low-cycle protection of the switch in parallel with the system of our factory should be operated, otherwise it should be performed manually, and when the system frequency is restored to the above, it should be parallel with the system as soon as possible.

13. Precautions for high-voltage equipment inspection.

Answer: When inspecting high-voltage equipment, no other work shall be carried out, and no fence shall be removed or overcome. During thunderstorms, wear insulated boots and do not approach lightning arresters and lightning rods.

When the high-voltage equipment is grounded, the indoor shall not be close to the fault point within 4m, and the outdoor shall not be close to less than 8m. To enter and exit the high-pressure chamber, the door must be locked.

14. How does a synchronous generator generate three-phase alternating current?

Answer: the steam turbine drives the rotor to rotate, and there is an excitation winding on the rotor, and the sub-winding is in contact with the slip ring through the brush, and the direct current generated by the excitation system is introduced into the rotor winding to produce a stable magnetic field, and the three-phase stator coil is driven by a certain speed rotation of the steam turbine, and the three-phase stator coil keeps cutting the rotor flux, generating induced electromotive force, and generating load current after carrying the load, that is, three-phase alternating current. (Alternating:.)

Alternating currents with equal frequency and potential but different phases).

If the load resistance value is uncertain, the target voltage cannot be obtained by the string resistance method.

The size of the resistance should be selected for the resistance buck mainly depends on the current flowing through the resistor, and the greater the current flowing through the resistor, the greater the voltage drop generated by the resistor.

If the load needs only one voltage, which has no current demand, it can be realized with two resistors, and the two resistors are connected in series to the ground, and the midpoint voltage value is taken. If the load wants current, mind using DC to DC scheme.

Hello, 72V to 5V string with 670 resistor. According to Ohm's law, there is a relationship between the resistance value r of a resistor and the current i passing through it, and the voltage difference v across the resistor: v = i r.

Assuming that the voltage from 72V needs to be reduced to 5V, then the voltage difference through the resistor is 72V - 5V = 67V. Also, if we assume that the current of the circuit through the resistor is i, then we can get v = i r according to Ohm's law, i.e., i = v r. Substituting the above two equations into Ohm's law, we get the resistance value r = v i = 67v i.

Therefore, if the magnitude of the current is known, the required resistance value can be calculated using this formula. For example, if the current in the circuit through the resistor is 100 mA, then the required resistance value is: r = 67v = 670 Therefore, if you need to reduce the voltage from 72V to 5V, and the current through the resistor in the circuit is 100 mA, then you can use a 670 resistor to achieve it.

Please note that since resistors consume a certain amount of power, BIRU should pay attention to whether the power value is sufficient when selecting a resistor.

1. Calculation method of buck resistance: r=(42-12) i You don't know the current i at present, so you can't find the value of r.

2. If the power p of the 12V load is known, then the problem of i=p u=p 12 will be solved.

V drops to 12V, the voltage on the step-down resistor is 36V, accounting for 75% of the total voltage, the power consumed on the step-down resistor is 36 I, and the power consumed by the step-down resistor is 3 times the load power.

It depends on the rated current of the electrical appliance, and then calculates the partial voltage.

That depends on what your circuit diagram looks like.

This takes into account your appliances. Different electrical appliances have different structures such as resistance and motors, and the resistance that needs to be added for voltage modification is naturally different.

If you are using an electrical appliance with a pure resistance that is only of power, then use Ohm's law to calculate it.

If you want to get a stable 127V power supply here, then you need to connect a transformer instead of a resistor. The transformer of a mobile phone will limit the electricity to a few volts, while the transformer of a computer is around 20V to 30V. Basically, it is impossible to adjust to 127 volts at home.

I don't know what you're going to do when you change the voltage, but buy an electrician's transformer just to be on the safe side.

It provides you with the formula for calculating the size of the resistance that needs to be added to the circuit when providing 127V voltage to the pure resistor R

rx=r*93/127

Hope it helps.

It depends on the size of the load resistance, reducing 220V to 127V is actually the voltage division of two resistors.

According to i=u r

The electric hall is not flowing!

The socks are repented with u1 r1 = u2 r2

So u1 u2=r2 r1

12V to 8V is to change the voltage to the original 2 3.

So the resistor will change to the original 3 and check the positive 2!

The current required for your state group file 8V is added to 300mA, and you calculate it according to the following formula, and the current is not the same as your own substitution or substitution:

Resistance size = (12-8) ohms.

The current is 500mA = and the resistance is = (12-8) ohms.

1. Calculation method of buck resistance: r=(42-12) i You don't know the current i at present, so you can't find the value of r. 2. If the power p of that 12V load is known, then:

i=p u=p 12 This problem is solved v drops to 12v, and the voltage on the buck resistor is 36v, accounting for 75% of the total voltage, on the buck resistor.

1. Calculation method of buck resistance: r=(42-12) i You don't know the current i at present, so you can't find the value of r.

2. If the power p of the 12V load is known, then the problem of i=p u=p 12 will be solved.

V drops to 12V, the voltage distributed on the buck resistor is 36V, accounting for 75% of the total voltage, the power consumed on the buck resistor is 36 I, and the power consumed by the buck resistor is 3 times the load power, which is simple and feasible in small current circuits, but if it is a large current, you should find another way.