What is transformer current?
Current is the one quantity a series circuit shares. The CCR sets a single loop current, it flows through every transformer primary, and a 1:1 isolation transformer passes the same current to its fitting.
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Transformer current is the current through a series isolation transformer. The CCR forces one constant current round the whole loop, so every primary carries it, and a transformer with a 1:1 current ratio (for example 6.6 A : 6.6 A) delivers the same current to its fitting through the secondary.
The current is chosen by the CCR, not by the load. A heavier or lighter fitting changes the voltage across its transformer (see Transformer Voltage), never the current. Brightness follows the loop current in steps, so raising the step raises the current through every transformer at once. If the loop is opened or a secondary is left open, a dangerous voltage can appear across the break: treat every lead as live and isolate the circuit under site procedures before work.
Frequently Asked Questions
Q1What is transformer current in AGL?
The current through a series isolation transformer’s windings. The CCR holds one constant current in the whole series loop, so the primary carries the loop current and, with a 1:1 current ratio such as 6.6 A : 6.6 A, the secondary carries the same.
Q2Is the current the same through every transformer on the loop?
Yes. Every primary is in series, so the same current flows through all of them. A heavier or lighter fitting changes the voltage across its transformer, not the current through it.
Q3How does current set the brightness?
The CCR changes the loop current in steps, and the lamp or LED output follows that current. For example, a typical 5-step regulator runs about 2.8, 3.4, 4.1, 5.2 and 6.6 A, with 6.6 A the brightest step.
Q4What happens to the current if a fitting fails or its secondary opens?
The loop current is unchanged because the CCR keeps regulating it. The fitting goes dark, and an open secondary can show a much higher voltage than normal and heat the transformer, so treat it as live and have it corrected promptly.
Q5Why must a series circuit never be opened while energised?
If the loop is broken, the CCR tries to force its current through the gap, producing a dangerous voltage across the break. Isolate and make the circuit safe under site procedures before touching any primary lead, connector or cable.
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