The earthing of Airfield Ground Lighting (AGL) series circuits for maintenance purposes has always proved a challenge. Even with a circuit isolated, there is still the possibility of having induced voltages on the cables. Present-day safety regulations require a dead circuit as a safe working platform before any work can commence. However this is very difficult to achieve so a compromise had to be reached.
Cable termination panels were introduced to help eliminate this problem. Nevertheless, with the use of exposed metal links within the panel, this still meant that there was some risk for maintenance staff.
A moulded switching unit was developed to replace this link board within the termination panel. When placed between the Constant Current Regulator (CCR) and the AGL field circuit, the unit can be safely disconnected, isolated and earthed by the simple rotation of the connector lid, without exposing the user to high voltages.
The design process ensured that the Series Circui Cut-out Switch (SCCS) has the ability to be retrofitted into cable termination panels, is suitable for installation inside the Micro 100 CCR as well as other manufacturers’ models, and, if necessary, can be used as a stand-alone unit.
THE SCCS complies with the following standards: ICAO Annex 14: Vol. 1, 4th edition, July 2004 and CAP168: chapter 6, section 13.4.5.
Applications
The SCCS enables the airfield ground lighting field series circuit to be safely disconnected. It is isolated and earthed by the simple rotation of the connector lid, not exposing the user to high voltages and therefore making it safer to use.
Features:
- The normal running position connects the CCR to the field circuit
- The field earthed position open circuits the CCR output and the grounds the field circuit
- The CCR test position applies a short circuit to the CCR and grounds the field circuit. This enables commissioning of the control system and CCRs without applying power to the airfield lamps
- An optional facility allows for CCR control loop micro-switches to be fitted
- A safety-lock facility is available when in the field earthed position
- Built-in functionality for use in CCR change-over cubicles
- The cable clamps facilitate the screened cable to be earthed easily if required
- Options include cable entry from the side or below
- An alternative lid to permit meter connections for field circuit measurements is available
Advantages:
- Allows easy and safe access for testing of field circuits
- Suitable for installation inside constant current regulators
- Designed to allow optional current monitoring facility to be mounted
on the rear of the unit
Technical Data:
- Electrical components moulded in polyurethane compound
- Operating temperature: -40°C to +55°C
- Circuit rating: max 5,000V
- Weight: 3kg
The ATG SCCS is currently in service at Heathrow Airport, Gatwick Airport, Durham Tees Valley Airport, Bristol International Airport, Sumburgh Airport, RAF Brize Norton and RNAS Culdrose.