What is the maximum current the interlock circuit shall draw from the aircraft's 28 VDC supply?

What is the maximum current the interlock circuit shall draw from the aircraft's 28 VDC supply?

• A. 5 milliamperes
• B. 10 milliamperes
• C. 20 milliamperes
• D. 40 milliamperes

Answer: (C)

Interlock circuits are safety/monitoring paths that should use only a tiny portion of the aircraft’s 28 VDC power. They’re supervisory by design, so keeping the current draw very small helps keep the bus voltage stable, reduces heat, and leaves headroom for other equipment on the same power system. The best choice here is the middle option because it represents a modest, sufficient load to power the interlock’s sensing and any status indication without imposing unnecessary burden on the electrical system. If the current were too high, you’d risk voltage drop and wasted power; if it were too low, the interlock might not operate reliably. So the maximum current is kept at a small, controlled level, as reflected by that middle choice.

Interlock circuits are safety/monitoring paths that should use only a tiny portion of the aircraft’s 28 VDC power. They’re supervisory by design, so keeping the current draw very small helps keep the bus voltage stable, reduces heat, and leaves headroom for other equipment on the same power system. The best choice here is the middle option because it represents a modest, sufficient load to power the interlock’s sensing and any status indication without imposing unnecessary burden on the electrical system. If the current were too high, you’d risk voltage drop and wasted power; if it were too low, the interlock might not operate reliably. So the maximum current is kept at a small, controlled level, as reflected by that middle choice.