BOMA Instrumentation & Controls Practice Test 2026 - Free Practice Questions and Study Guide

Two-position control, also known as on-off control, is characterized by its binary action of fully activating or deactivating a device, such as a heater or valve, without any modulating capabilities. This type of control can lead to significant overshoot and undershoot because it responds quickly to changes but does not adjust gradually. As a result, the system can overshoot its target setpoint when the control action activates and may undershoot when it shuts off, resulting in oscillations around the desired level.

In contrast, proportional control adjusts the output based on the error and generally results in a steady-state error but avoids large overshoots. Integral control addresses steady-state error over time but also can lead to overshoot if the integral action accumulates too much over time. Derivative control anticipates future errors based on the rate of change, which helps in smoothing responses but does not inherently cause significant overshoot or undershoot. Thus, the nature of two-position control fundamentally leads to the high overshoot and undershoot events described in the question.