Pressure switches cause supervisory signals for air pressure deviations greater than what value?

Pressure switches cause supervisory signals for air pressure deviations greater than what value?

• A. ±5 psi
• B. ±10 psi
• C. ±15 psi
• D. ±20 psi

Answer: (B)

Pressure switches monitor the actual air pressure and only send a supervisory signal when the measured value moves beyond a defined limit from the desired setpoint. That limit is chosen to balance sensitivity and reliability: you don’t want alarms for every tiny fluctuation, but you do want to catch real problems that could affect performance. In this case, the switch is configured to trigger when the pressure deviates by about ten psi in either direction. When the pressure drifts more than ten psi above or below the setpoint, the supervisory signal is generated, indicating a fault or abnormal operating condition that needs attention. The system typically includes hysteresis, so it won’t flip back and forth rapidly; it will only reset once the pressure crosses the opposite threshold, which reduces chatter. Choosing a smaller threshold would lead to nuisance alarms from normal variation, while a larger threshold could delay fault detection.

Pressure switches monitor the actual air pressure and only send a supervisory signal when the measured value moves beyond a defined limit from the desired setpoint. That limit is chosen to balance sensitivity and reliability: you don’t want alarms for every tiny fluctuation, but you do want to catch real problems that could affect performance.

In this case, the switch is configured to trigger when the pressure deviates by about ten psi in either direction. When the pressure drifts more than ten psi above or below the setpoint, the supervisory signal is generated, indicating a fault or abnormal operating condition that needs attention. The system typically includes hysteresis, so it won’t flip back and forth rapidly; it will only reset once the pressure crosses the opposite threshold, which reduces chatter.

Choosing a smaller threshold would lead to nuisance alarms from normal variation, while a larger threshold could delay fault detection.