Loops designing voltage feedback

The only function of the voltage feedback loop is to hold the output voltage(s) at a constant value. Complications arise in areas such as transient load response, accuracy of the output(s), multiple outputs, and isolated outputs. All of these individually can be nightmares for the designer, but if the design approaches are understood then each factor can easily be satisfactorily addressed. 

The furnace is heated by low voltage (usually 10 V) and high current (up to 500 A) from a well stabilized step-down transformer. For optimum precision, the voltage should be well stabilized, often by a feedback loop which may be temperature feed-back based (see Section 3.6.1). A rapid rise-time of the temperature is also preferable, because of theoretical considerations of peak shapes. This has implications for power supply design and furnace design, as will be shown below. Currently, furnaces are available that reach temperatures of up to 3000°C, and temperatures of 2500°C should be reached in less than 2 s in a well designed furnace. 

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