How is a CCR selected?
Four decisions, taken in order, that narrow the choice to the right constant current regulator for a series circuit.
A constant current regulator drives one series circuit, so it is chosen to suit that circuit and the site it sits in. The circuit load sets the kW rating, the output current and steps must match the fixtures and the lighting design, the supply must match the airfield power, and the control and location decide the interface and cooling.
The flowchart only narrows the choice. The final CCR is confirmed against the design for rating at the top step, output current and steps, input supply, control and monitoring and cooling, and against the standard it must meet.
Frequently Asked Questions
Q1How is a constant current regulator selected?
By working through a few decisions in order: the load the circuit draws at the top step, the output current and number of intensity steps, the supply that feeds it, and how it will be controlled and housed. The result is then checked against the data sheet and standard.
Q2Why must the CCR be sized for the circuit load?
The CCR has to supply every lamp plus the transformer and cable losses at the top step. If it is too small it cannot hold the current on the higher steps and the lights run dim or it trips. One that is far too large runs inefficiently at light load, so the next standard size up with sensible margin is chosen.
Q3What decides the output current and the number of steps?
The series circuit and fixtures decide the rated output current, commonly 6.6 A at the top step for a Class 1 circuit (Class 2 is 20 A), and the lighting design decides whether three or five intensity steps are needed. The CCR must offer the steps the control system will call for.
Q4Why does the input supply matter?
The CCR draws from the airfield supply at the voltage, phases and frequency on its rating plate. The input must match the site supply, and the input protection is sized from the CCR’s input current, which follows from its rating, efficiency and power factor.
Q5What should be checked before the choice is final?
That the kW rating covers the load with margin, the output current and steps match the design, the input matches the supply, the control and monitoring interface suits the airfield control system (L-829 monitored or L-828 unmonitored, as the design requires), and the cooling and enclosure suit the vault. The manufacturer’s data sheet and the standard decide.
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