Bailey 820 Line of controller cards, 6624120F1 Signal Lag.
The Bailey 820 6624120F1 is a legacy Signal Lag Action Module originally manufactured by Bailey Controls (now part of ABB). Introduced in the early 1970s, the Bailey 820 Integrated Control System utilizes a "split" architecture specifically engineered for modulating boiler controls in power stations, notably within Babcock & Wilcox (B&W) Integrated Control Systems (ICS). The 6624120F1 module is an analog hardware circuit designed to damp process noise or deliberately delay control response loop transitions by introducing a first-order lag filter to a standard DC current signal.