The Lead Compensator module (see the lower portion of Figure 2) was introduced at CCT Release 5.1. It attempts to remove some of the dynamics of a control loop caused by oversized valves or valves with nonlinear flow characteristics by speeding up the controller responses. The effect is similar to adding derivative action to a control loop.
In standard applications, the Lead Compensator module provides an alternative output, commonly used in VAV zone temperature control. In Discharge Air Temperature Reset from Zone Control applications, it is used for supplemental heating, but it is not used for box heating or cooling control loops. The Lead Compensator is not implemented in Discharge Air Temperature control loops because those control loops operate fast enough to overcome a valve's nonlinear characteristic.