The lights at the Taxiways and Runways are usually fed from CCR (constant current regulator). Typical setups are either three or five brightness steps. Depending on the load the maximum CCR size commercially available is
30 kW, the smallest is 4 kW (applicable for new LED lights). Lights are supplied through the series transformers, 1:1 ratio. In Canada the secondary of the isolation transformers are grounded, in US their are not (BTW, I would like to know how it is in the other countries, what do you think about pros and cons). The high voltage side of the series circuit is ungrounded. The cables connecting the primaries of the series transformers are 5kV rated, usually #8 AWG, some times #6 AWG, in older installation directly buried (incl. xfrm), in new installations the tendency is to use pipes and pulpits. The current values and % lighting levels are as follow:Step RMS Current (A) Percentage Lighting Level
Step 1 2.8A 0.15 Step 2 3.4A 1.2 Step 3 4.1A 5 Step 4 5.2A 25 Step 5 6.6A 100
BTW Harry C, the series constant current circuits were first used in the street lighting.
Art.
Can someone describe how taxiway and runway lighting is served? (in the US)
> The long distances would seem to make voltage drop a major issue. >
>