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Automating Manufacturing Systems - Process Control and ...

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plc analog - 22.19<br />

A<br />

t<br />

V eff<br />

=<br />

A<br />

A<br />

t<br />

V eff<br />

=<br />

------<br />

3A<br />

4<br />

A<br />

t<br />

V eff<br />

=<br />

A<br />

--<br />

2<br />

A<br />

t<br />

V eff<br />

=<br />

A<br />

--<br />

4<br />

A<br />

t<br />

V eff<br />

= 0<br />

Figure 22.15<br />

Pulse Width Modulated (PWM) Signals<br />

PWM is commonly used in power electronics, such as servo motor control systems.<br />

In this case the response time of the motor is slow enough that the motor effectively<br />

filters the high frequency of the signal. The PWM signal can also be put through a low<br />

pass filter to produce an analog DC voltage.<br />

www.PA<strong>Control</strong>.com

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