UFC 3-535-01
17 November 2005
Table 12-2. Intensity Requirement Levels for Various Circuits
Amperage
Amperage
Approximate
Reading
Reading
Percent
Brightness
20-Ampere
6.6-Ampere
Rated
Step
Circuit
Circuit
Intensity
1
8.5
2.8
0.16
2
10.3
3.4
0.80
3
12.4
4.1
4.00
4
15.8
5.2
20.00
5
20.0
6.6
100.00
12-1.13.2
The brightness steps for three levels of lamp intensity are achieved by
varying the current in the lighting circuit as follows:
Brightness
Service Systems
Percent
Level
Lamp Current (amps)
Brightness
High
6.6
100
Medium
5.5
30
Low
4.8
10
12-1.14
Special Considerations for Series Circuits
12-1.14.1
Selection of 6.6 or 20 Amperes Circuit
The determination of whether to use a 6.6 amperes or 20 amperes series circuit must
be based on several factors relating to the characteristics of the circuit and the
anticipated conditions under which the circuit will be operated. In general, if a circuit is
not expected to operate at highest intensity more than 5 percent of the time, and if
design calculations show that the voltage will not exceed 2400 volts when operated at
the mid level (step 2 for 3-step circuits, step 3 for 5-step circuits), then a 6.6 ampere
circuit is recommended. If a circuit is expected to operate at highest intensity more than
5 percent of the time, and if design calculations show that the line voltage will be more
than 2400 volts at the mid-level, then consideration should be given to using a 20
amperes circuit, or alternatively using more than one 6.6 amperes circuit. Analysis
should consider the economics over the expected life of the system, typically 20 years.
A more detailed discussion of this can be found in Chapter 15. Recommend designing
for multiple 6.6 ampere circuits instead of 20 ampere circuits.
12-1.14.2
REIL on Series Circuits
REIL (runway end identifier lights) are typically connected to the runway edge lighting
series circuit via power adapter, or to a separate power source of 120/240 volts. If
connected to a series circuit, it is necessary to consider the sizing of the regulator
carefully to allow for the pulsing type of load. The impact on the constant current
regulator may up to 10 times the power requirement indicated by the manufacturer.
More information on this can be found in Chapter 15.
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