Air port Lighting 5

[prc]

It is said that for air port lighting series lighting circuits are used.Why such a system is used ,instead of normal parallel circuits.Why a constant current regulator ,solid state controland ferro resonant type transformer are required?What are the salient features of ferroresonant type transformer.Who makes such transformers?

 

[dpc]

Check this out:

http://www1.faa.gov/arp/publications/acs/5340-24.pdf

Series lighting circuits are more economical for long runways, and also make dimming more reliable since all lights see the same current.

Runway lighting design is pretty much cut and paste based on FAA requirements.

 

[Laplacian]

Here is one manufacturer:

http://www.flightlight.com/airportlighting/pages/content.html#regs

 

[mouli11]

1.The airfield lighting is provided for effective visual guidance to pilot for identifying the Runway amidst so many lighting available around the airfield. The illumination level is directly proportional to current. Hence, to achieve the equal illumination all along the runway constant current system is used.
2The disadvantage of parallel circuit is , since the runway lengths are high (9000 ft to 12000ft)in a parallel circuit the light intensity decreases with line drop along the circuit and thereby illumination level is reduced at the far end of the circuit this gives wrong guidance to the pilots who is approaching the runway at very high speed.
3.Some of the advantage of series circuit is given below.
a)A single conductor cable of one conductor size and insulation voltage is used throughout the length.
b)The intensity control of the lamps can be effectively controlled for wide range, to meet different ambience light condition.
c)Since the system is effectively earthed, with one ground fault the system works without effecting the operations.
d)Ground faults can be easily located in series circuit. However, open circuit faults identification is difficult.
4.When compared to parallel light system the series lighting system is expensive due to heavy cost of constant current controller and isolating transformer used for each fitting.
5.The present generations CCRs are manufactured using solid state technology Thyrister type for effective intensity control and circuit protection. Resonant circuits are not presently used in CCRs.
6.One of the majour concern in Series circuit is the very high voltages prodused in open circuit.This aspect is delt efctively by solid state type CCRs.

 

[advidana]

try

http://www.chalp.com/

it's the crouse hinds airport lighting products it is all you will need.

 

[jbartos]

Comments on:
1. Series lighting circuit:
a. Drawbacks:
a1. The series circuit provides difficulties in locating any of its opening. The troubleshooting tends to be time consuming and labor cost intensive.
a2. The current regulation is less widespread than voltage regulation.
a3. Any short in individual loads, if not promptly serviced, potentially increases voltage on the remaining loads.
a4. Etc.
b. Advantages:
b1. Single conductor circuit.
b2. Luminaires are equally lit within the circuit.
b3. Current regulation accomplishes equal illumination of luminaires.
b4. Etc.
2. Parallel lighting circuit:
a. Drawbacks:
a1. Two-conductor circuit is required.
a2. Illumination of luminaires is decreasing with circuit length/voltage drop.
a3. Lamps/luminaires with different voltage ratings would be needed to compensate for the voltage drop.
a4. If one lamp or luminaire opens during a plane approach, and one side of runway is less lit, a safety concern is posed.
a5. Etc.
b. Advantages:
b1. One burned lamp is easily detected and replaced with small cost.
b2. Parallel circuit dimming is more widespread.
b3. Voltage drop can be offset by different wire AWG sizes.
b4. Cable deterioration and current to ground leakages can be detected or monitored.
b5. Better safety to an approaching plane for landing since one burned lamp will not pose a major lapse in the runway illumination.
b6. Etc.

 

[GOTWW]

There are things called isolation transformers that are used on ALL appliances. THEREBY OPEN CIRCUITED OR SHORT CIRCUITED LIGHTS ETC. HAVE NO EFFECT ON THE OPERATION OF THE OTHERS. since the circuit is constant current, the loss of individual devices does not increase the burden on the rest of them.

 

[prc]

Thank you for all the valuable information esp for dpc,mouli11&advidana.Why ferroresonant trf?Is it same as isolation trf?Can any one enlighten?

 

[GOTWW]

The ferro-resonant transformer is the 6.6A or 20A 10-50KW constant current source they are fed from 2500V with the newer designs now running 480V primary. The requlator output voltage is in the MV range so appropriate cables are required (FAA type B typ. #8 for 6.6A or #6 for 20A). They are more efficient (input power varies with output power) that the cheaper SCR based designs that basically draw a fixed load independent of output load. The isolation transformers are small, generally 1:1 transformers that are installed below grade in the bases. If you have a legitament application, just contact one of the airfield lighting sales reps, they will be more that happy to help you out. One cool new development is LED based taxiway lighting that require only 8.8W vrs 45W of old, and bullet proof to boot.

 

[jbartos]

Suggestion: Visit

http://www.elect-spec.com/trnsreg.htm

http://www.power-one.com/technical/articles/topo_e.pdf

for Ferro-resonant transformers
The output V-I characteristics allows the secondary to be short-circuited.

Please notice, that the ferro-resonant transformers do not preclude the lighting circuit in series to be down when a bad connection opens the circuit or the conductor degrades and open the circuit.