UFC 3-535-01
17 November 2005
12-1.11.1
Control Voltages
Standard practice is to provide a 120 VAC control system using low burden pilot relays
(pilot relay assemblies) to activate the power switches, contacts, and relays controlling
the regulators and transformers supplying power to the airfield lighting circuits. The
maximum horizontal distance from the control tower to the lighting vault is limited, for
proper function of the pilot relay assemblies, to 2,240 meters (7,350 feet) when using
120 VAC control systems. Where the distance between the tower and the vault exceeds
the maximum, consider using a 48 VDC control system as described in FAA AC
150/5340-24. Where both types of control system are installed, ensure the control
power systems are isolated. (See Figure 12-3.)
12-1.11.2
Control Circuitry
Design the control system to ensure the following:
12-1.11.2.1 Lighting on intersecting runways cannot be energized simultaneously.
12-1.11.2.2 All circuits supplying the lights for any one lighting system (for example,
runway edge lighting) are energized simultaneously and operated at the same
brightness step.
12-1.11.2.3 Runway centerline lights cannot be energized unless the runway edge
lights are energized.
12-1.11.2.4 Touchdown zone lighting (TDZL) cannot be energized unless the runway
centerline lights are energized.
12-1.11.2.5 Certain systems associated with low-visibility operations (such as runway
guard lights, hold-position lights, lead-in lights, land-and-hold-short lights), if installed,
may also require linkage of control to runway lights. Recommend following guidance of
applicable FAA documents, such as FAA AC 120/57, Surface Movement Guidance and
Control System (SMGCS)and FAA AC 150/5345-46.
12-1.11.3
Control System Modernization
Major commands are encouraged to consider the use of multiplex control systems,
where significant economies or operational improvements can be achieved. If an
approved specification is not available, the use of such systems is subject to the
requirements of paragraphs 1-10 or 1-11 of this document. Control systems using
electromagnetic emissions also require the express approval of HQ AFCESA/CESM.
Paragraph 13-16 provides guidance for computerized control systems. As examples,
Figure 12-4 shows a block diagram for a control system using programmable logic
controllers (PLC), and Figure 12-5 shows a block diagrams for a PC-based control
system. Further discussion of computerized control systems is also provided in Chapter
15.
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