The CCR system at a glance
A constant current regulator turns the incoming supply into one steady current for a whole series circuit. This is how its main blocks fit together.
1It holds the current, not the voltage
A series circuit lights every lamp from one loop of current. The CCR keeps that current at the value set by the brightness step, even as the supply or the load changes. That is why every light of the same type on the circuit gives the same output.
2The main blocks
The input side takes the supply through a breaker and surge protection. The regulator stage controls the output current. The output side feeds the series loop. A control board selects the brightness step and reads the monitors.
3Control and protection sit around it
Brightness is selected locally or by remote control from the ALCMS. Monitors watch supply, output current and temperature. A critical fault such as an open circuit shuts the output down rather than let the voltage rise.
| Element | Detail |
|---|---|
| Input | Incoming supply, breaker, surge protection |
| Regulator | Holds the output current at the selected step |
| Output | One series circuit, one current |
| Control | Brightness step, local or remote selection |
| Monitoring | Supply, output current, temperature, circuit condition |
| Technology | Ferroresonant, thyristor or IGBT based; see the technologies entry |
Frequently Asked Questions
Q1What does a CCR do?
It supplies one constant current to a series lighting circuit, so every light on the loop receives the same current whatever the supply or the number of lights in service.
Q2Why not use a constant voltage supply?
Light output depends on the current through the lamp. In a series circuit one loop carries the same current through every lamp, so holding it constant gives equal output whatever the cable length. Each lamp is fed through an isolating transformer, so a failed lamp does not break the loop.
Q3What happens if the series circuit opens?
The CCR would try to force the set current through a broken loop and the output voltage would rise to a dangerous level. Open-circuit protection detects this and shuts the output down. Never open an energised series circuit.
Q4Is every CCR built the same way?
No. Ferroresonant, thyristor and IGBT designs regulate differently, and models differ in controls and monitoring. The block layout here is a general guide.
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