Title
L-828, Type L-829 Ferroresonant Constant Current Regulator (CCR) - Understanding the S-1 Cutout
URL Name
Understanding-the-S-1-Cutout-Operation-and-Safety
Summary
Explains the function of the S-1 cutout switch, how it affects CCR output, and why it must not be used as a substitute for proper lockout/tagout procedures.

Content

Overview

The S-1 cutout switch is provided on the CCR to short the output of the regulator when placed in the OUT position. It is intended for specific operational and testing purposes. It does not remove input power from the CCR. Primary power to the CCR should always be shut off and locked out before removing the handle assembly.

Handle Positions

Handle IN: CCR output is connected to the series circuit. Normal operation is permitted. Output current flows to the airfield lighting loop.

Handle OUT: CCR output terminals are shorted. The series circuit is disconnected. The regulator sees a shorted output condition. This allows certain service and testing conditions without an open-circuit voltage condition.

What the S-1 Cutout Does

When placed in the OUT position, the output is shorted internally. The regulator does not experience open-circuit voltage rise. The series circuit is isolated from the regulator output. This prevents dangerous open-circuit voltage from developing at the output terminals. With the handle assembly removed, the SPC isolates the CCR output from airfield series loop for maintenance personnel safety. The SPC also shorts the series loop and shorts the regulator secondary aiding in maintenance checks and troubleshooting.

What the S-1 Cutout Does NOT Do

The S-1 cutout does not remove input power. It does not de-energize internal components. It does not eliminate electrical hazards inside the cabinet. It is not a substitute for lockout/tagout procedures. Input voltage remains present unless upstream power is disconnected and locked out.

Safety Warning

Never rely on the S-1 cutout as a safety device. Before performing service, de-energize input power. Apply lockout/tagout. Verify absence of voltage using properly rated test equipment. The presence of the S-1 in the OUT position does not ensure the cabinet is safe to open or service. Primary power to the CCR should always be shut off and locked out before removing the handle assembly.

Some personnel assume placing the S-1 cutout in the OUT position makes the CCR safe. This is incorrect. The S-1 only affects the output circuit condition. It does not eliminate internal electrical hazards.



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

Constant Current Regulator