What is the main purpose of a loop integrity test?

What is the main purpose of a loop integrity test?

• A. To verify the loop is continuous and fault-free; methods include insulation resistance, continuity check, resistance to common-mode faults
• B. To measure the loop's temperature profile
• C. To set alarm thresholds
• D. To test only the power supply to the loop

Answer: (A)

Loop integrity testing ensures the measurement loop that carries the signal from the sensor to the control system is intact and fault-free. The main goal is to confirm there are no opens, shorts, or insulation problems that could distort or interrupt the signal. This is done with tests like insulation resistance to detect leakage, continuity checks to ensure a complete path, and resistance to common-mode faults to guard against interference. These procedures validate that the loop can reliably transmit the 4-20 mA signal under normal operation. Measuring the loop’s temperature profile, setting alarm thresholds, or testing only the power supply do not address the physical continuity and insulation issues that loop integrity testing targets.

Loop integrity testing ensures the measurement loop that carries the signal from the sensor to the control system is intact and fault-free. The main goal is to confirm there are no opens, shorts, or insulation problems that could distort or interrupt the signal. This is done with tests like insulation resistance to detect leakage, continuity checks to ensure a complete path, and resistance to common-mode faults to guard against interference. These procedures validate that the loop can reliably transmit the 4-20 mA signal under normal operation. Measuring the loop’s temperature profile, setting alarm thresholds, or testing only the power supply do not address the physical continuity and insulation issues that loop integrity testing targets.