# Frequency and voltage relationship

### What is relation between frequency and voltage?

However, the specific relationship between voltage and current is very circuit In AC circuits, we have to consider the frequency and phase. Frequency and Voltage are different things. Voltage is defined in basic electric principles (Physics: Mr. Voltaire) as the potential difference that pushes a current . This is my basic dout not only this and many dout about frequency also . Just think of the ohms law equation (voltage=amperage times resistance) E=I X R with .

It still is as bright as before, still dissipates w. The difference is, the voltage across the bulb is the opposite of what it was before, and the current is the opposite also, but when they are multiplied, the power is still positive.

Suppose you reverse the connections 60 times per second, or, or a million.

Electricity Pain versus Frequency

How much power does the light bulb dissipate? The same, because there is no time when V times I is not equal to w.

Typical wall power is not like that, of course. Rather than instantaneously switching between positive and negative voltage, it swings smoothly with a sinusoidal curve. So the light bulb dissipates maximum power when the voltage is maximum in the positive direction, zero when the voltage is zero, and maximum again when the voltage is maximum in the negative direction.

So if the wall frequency is 60hz or 50hz or hz in some airplanesthe power dissipation actually varies between maximum and zero at a rate of twice that. But since the filament takes a longer time to get hot and cool down, it seems to be on steadily. The running average power is constant. Now, if there are different kinds of load, such as an inductive or capacitive load, or a mixture, you get different power dissipation, because the current is not necessarily in sync with the voltage.

A typical AC motor manufactured for use in the U. For example, increasing the frequency without increasing the voltage will cause an increase in speed and a decrease in air-gap flux density.

### What is the relation between frequency and voltage | All About Circuits

Thus, for a motor to produce its rated torque at variable speeds, it also is necessary to control the voltage and frequency supplied to the motor. Motors operated with constant flux are said to have constant torque. AC drives change the frequency to vary the speed of the motor and change voltage proportionately to maintain constant flux.

Some examples of constant torque loads are: Such applications need less torque at higher speeds, yet require voltage to be no higher than the rated nameplate voltage because the motor insulation deteriorates exponentially at higher-than-rated voltage. Because the motor horsepower is directly proportional to the torque and speed of the motor, it remains constant while torque decreases in proportion to the increase in frequency.

As such, a motor that is operated above its rated frequency is operating in a region known as constant horsepower see Fig. The drive starts and accelerates the motor smoothly as frequency and voltage are gradually increased to the desired speed.

A load that needs more starting torque than a drive can deliver requires a drive with a higher current rating.

### Alternating current motor drives -

It is appropriate to supply a drive with a higher continuous horsepower rating than the motor when high peak torque is required. Selecting a motor AC drives often have more capability than the motor. Drives can run at higher frequencies than might be suitable for an application.