What is current regulation?
Keeping the current in a lighting loop at a set value, whatever else changes. The regulator measures the current and nudges its voltage, again and again, so every light keeps the same output.
A series loop only works well if its current is right. But the supply drifts, lights are added or fail, and cable resistance changes with temperature. Current regulation is the control that cancels all of that out.
1Why hold it constant
Light output depends on current. If current drifts down, the lights dim, and if it drifts up they are too bright and a lamp’s life can shorten sharply. Holding the current steady keeps every light matched and every lamp inside its design range.
2Measure, compare, adjust
The regulator measures the loop current, compares it with the set value and adjusts its output voltage to close the gap. That is a feedback loop, running all the time. A brightness step is simply a different set current, so the same control gives every intensity level.
3Its limits
A regulator can only work within its rating. If the load is too large it cannot hold the current, and if the loop is open there is no current to regulate, so open-circuit protection is built in. Choosing the right rating is part of the circuit design.
| Term | Meaning |
|---|---|
| Set current | The value the regulator tries to hold, set by the brightness step |
| Measured current | What the regulator senses flowing in the loop |
| Regulation | Adjusting output voltage so measured matches set |
| Brightness step | A different set current, giving a different light output |
| Nominal full-brightness current | 6.6 A in a standard series circuit; lower steps are lower set currents |
| Rating | The load the regulator can drive and still hold the current |
| Open-circuit protection | Stops the regulator driving a broken loop |
Frequently Asked Questions
Q1What is current regulation in airfield lighting?
Holding the current in a series loop at a set value, even when the supply voltage, the number of working lights or the cable resistance changes. A constant-current regulator does this.
Q2Why must the current be held constant?
Light output depends on current. If the current drifts, the lights go dim or too bright, and a current that is too high can shorten the life of a lamp. A steady current keeps every light matched.
Q3How does a regulator hold the current steady?
It measures the loop current, compares it with the set value for the chosen brightness step, and adjusts its output voltage up or down to remove any difference. This repeats continuously.
Q4Can a regulator hold the current under any load?
No. It can only work within its rating. If the load is too large, or the loop is open, it cannot keep the current at the set value, so ratings and open-circuit protection matter.
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