Name: rms value for ac power measurement
Uploaded: 2024-07-08T13:19:51.000Z
Duration: 1 min 7 s
Channel: JoVE

Considere um circuito CA com uma fonte de tensão periódica conectada a um resistor.
A potência média fornecida ao resistor é igual à integral da potência instantânea durante um período dividido pelo período.
Quando este resistor é conectado a uma fonte CC, a potência média que ele absorve é o produto da corrente ao quadrado e sua resistência.
Considerando que a potência média fornecida por uma fonte CC ao resistor é equivalente à fornecida pela corrente periódica, a corrente contínua é igual ao valor efetivo da corrente periódica.
Portanto, o valor efetivo da corrente é a raiz quadrada da média dos valores de corrente instantânea ao quadrado.
Da mesma forma, a expressão para o valor efetivo da tensão pode ser obtida.
Para qualquer sinal periódico, o valor efetivo, também conhecido como valor quadrático médio da raiz, é igual à raiz quadrada da média do quadrado do sinal periódico.
Para uma corrente e tensão senoidal, o valor RMS é igual ao valor de pico dividido pela raiz quadrada de dois.

 valor efetivo de uma forma de onda periódica

Effective Value of a Periodic Waveform

O conceito de valor efetivo, o valor da raiz quadrada média (RMS), é crucial para a compreensão dos circuitos elétricos e do fornecimento de energia. Esta ideia surge da necessidade de medir a eficácia de uma fonte de tensão ou corrente no fornecimento de energia a uma carga resistiva.

O valor efetivo de uma corrente periódica representa a corrente contínua (CC) que transmite a mesma potência média a um resistor que a própria corrente periódica. Este conceito é crucial ao avaliar circuitos CA. Para determinar o valor efetivo da corrente, deve-se encontrar a corrente RMS, que é a raiz quadrada da média dos valores quadrados da corrente instantânea durante um período. Este valor RMS corresponde à CC que fornece a mesma potência média que a corrente periódica quando aplicada a um resistor.

<img alt="Equation 1" src="/files/ftp_upload/15119/15119_Equation_1.svg" style="height: 60px;">

Da mesma forma, o valor efetivo da tensão é calculado da mesma maneira que a corrente. Representa a tensão RMS, essencial para avaliar o consumo de energia em sistemas elétricos.

<img alt="Equation 2" src="/files/ftp_upload/15119/15119_Equation_2.svg" style="height: 60px;">

O valor RMS é um conceito fundamental, não limitado a sinais senoidais. Para qualquer função periódica, o valor RMS é calculado encontrando o quadrado da função, determinando a média dos quadrados e, em seguida, extraindo a raiz quadrada dessa média. Em aplicações práticas, a tensão e a corrente são frequentemente expressas em termos de valores RMS, em vez de valores de pico. Isto ocorre porque o valor médio de um sinal senoidal é zero, tornando o valor RMS uma métrica mais útil para análise de potência. Além disso, voltímetros e amperímetros analógicos são projetados para ler diretamente os valores RMS de tensão e corrente, tornando-os ferramentas indispensáveis ​​em medições de potência.

 Valor Efetivo de uma Forma de Onda Periódica

Considere um circuito CA com uma fonte de tensão periódica conectada a um resistor.
A potência média fornecida ao resistor é igual à integral do ...

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rms value for ac power measurement

The RMS value, or effective value, helps measure how much power a periodic voltage or current can deliver. It is the direct current, or DC, value that gives the same average power to a resistor as the periodic signal does. This idea is especially important in AC circuits.

To find the effective value of current, calculate the root mean square, or RMS, current. First square the instantaneous current values over one period. Then find the mean of those squared values and take the square root. The result is the DC current that would produce the same average power in a resistor.

The same method is used for voltage. The effective value of voltage is the RMS voltage, and it is used to judge power use in electrical systems. The RMS idea also works for any periodic function, not only sinusoidal signals.

For any periodic waveform, the RMS value comes from squaring the function, averaging the squared values, and then taking the square root. In practice, voltage and current are often given as RMS values instead of peak values. That is useful because the average value of a sinusoidal signal is zero, while the RMS value still shows its power effect.

Analog voltmeters and ammeters are designed to read RMS values directly. That makes them useful tools for measuring voltage and current in power circuits.

RMS Value for AC Power Measurement

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key terms and concepts

Learn how RMS, or effective value, compares AC voltage and current to DC power in resistive loads, and why it is used in electrical measurements.

RMS Value for AC Power Measurement | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

RMS Value for AC Power Measurement

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