As shown in figure "B" of the illustrated block diagram for a central operating system configured for supervisory control, what is becoming the industry standard for transmission of analog signals for a measured variable? EL-0094

Correct Answer: Option C — 4 milliamps to 20 milliamps

The 4-20 mA current loop is the industry standard for analog signal transmission because it is highly resistant to electrical noise and voltage drops over long cable runs. A 'live zero' of 4 mA allows the system to distinguish between a zero-value reading and a broken wire or circuit failure.