Question 564General Subjects - Assistant Engineer

The correct answer is C) 4 to 20mA. The 4 to 20mA current loop is an industry standard for analog electronic signals in instrumentation and control applications. This standard is widely used because it provides a robust and reliable signal transmission method that is less susceptible to noise and interference compared to voltage-based signals. The 4mA lower limit ensures that a zero signal can be differentiated from a broken or disconnected circuit, while the 20mA upper limit provides sufficient signal range for most measurement and control applications. The other options are incorrect because 0 to 10mA (A) is not a common industry standard, and 1 to 10A (B) and 4 to 20A (D) represent much higher current ranges that are not typical for instrumentation and control signals.