Question

On a KNX power supply unit, what does a YELLOW LED indicate?

KNX BasicLearnKNX InstallationMedium
Answer

D — An external voltage higher than 30 V has been applied to the bus side

Correct: Yellow indicates an external voltage above 30 V on the bus side.

Source

KNX Basic Course Documentation — 5.2 — p. 104

All proposed choices (exam context)
  1. A.The unit is overloaded, possibly due to a short circuit
  2. B.The 230 V mains supply has failed
  3. C.The power supply is active and within its normal operating range
  4. D.An external voltage higher than 30 V has been applied to the bus side
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Last updated: 19 May 2026

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