Overview

The Solid State Relay (SSR) is a power control device used to regulate the energy delivered to the ferroresonant transformer. Unlike the input contactor, the SSR is an electronic switching device with no moving mechanical parts.

Primary Function

The SSR controls current by regulating the power applied to the transformer. It adjusts conduction timing to allow precise control of output current. It operates under direction of the firing card and control circuitry.

Role in Brightness Step Control

The CCR operates in either 3-step or 5-step configuration. Each step corresponds to a defined percentage of full output current. The SSR modulates power to achieve the selected step. It maintains current stability during load variation. The control system adjusts SSR operation to maintain the programmed output current.

Interaction with Firing Card

The firing card sends control signals to the SSR. These signals determine when and how long the SSR conducts during each cycle. This controlled switching allows regulation of transformer excitation.

Advantages of Solid State Control

The SSR provides no mechanical contact wear, fast switching capability, precise current control, and reduced maintenance compared to mechanical switching devices.

Fault and Protection Behavior

If abnormal conditions occur, the control system may disable the SSR. Output current may be interrupted. Fault conditions may be logged by the DCMU. The SSR is part of the regulated output control system and responds to protective logic.

Safety Reminder

Although solid state, the SSR controls high-energy power circuits. Servicing must only be performed after proper lockout/tagout and verification of de-energization.

Airport Lighting Company | Type L-828, Type L-829 Ferroresonant Constant Current Regulator