§413
Automatic Power Off (AUV)
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§413 — Automatic disconnection of the supply
AUV is the protective measure against indirect contact in TN systems.
Operating Principle
In the event of an insulation fault between an active conductor and a conductive part with PE, a short-circuit current is generated that must be large enough to activate the protective device (fuse, MCB, RCD) within the permitted tripping time.
Disconnection Times (Table 41.1)
| System | U₀ ≤ 120 V | 120 < U₀ ≤ 230 V | 230 < U₀ ≤ 400 V | U₀ > 400 V |
|---|---|---|---|---|
| TN | 0.8 s | 0.4 s | 0.2 s | 0.1 s |
| TT | 0.3 s | 0.2 s | 0.07 s | 0.04 s |
Practice
- Final circuits ≤ 32 A: see table above.
- Distribution circuits and fixed equipment > 32 A: max. 5 s (TN) or 1 s (TT).
- For 30 mA RCD: tripping time ≤ 0.3 s at 1×IΔn and ≤ 0.04 s at 5×IΔn.
Further reading
Related guides