SENTRON 3VA2 line protection breaker — 1000 A frame with ETU320
The interrupting capacity is the standout spec for this frame: 187 kA at 240 V AC, 121 kA at 415 V, and 53 kA at 690 V. The ETU320 electronic trip unit provides adjustable long-time pickup (Ir) from 400 A to 1000 A and instantaneous pickup (Ii) from 1500 A to 10 000 A, with adjustable long-time delay (tr) from 0.5 to 17 seconds. This allows coordination with downstream feeders and branch breakers across a wide range of fault levels.
At 60 °C it derates to 955 A, at 65 °C to 885 A, and at 70 °C to 815 A. In a warm enclosure — common for a main breaker in a non-air-conditioned switchroom — that derating curve is the number that governs actual circuit loading, not the nameplate Iu. Dimensions are 210 mm wide, 320 mm high, and 120 mm deep. Front-face protection is IP40 — splash-safe for the switchboard face but not washdown-rated. Maximum power loss is 123 W. Account for this heat in the enclosure thermal budget.
The lower operating limit matters for unheated electrical rooms in cold climates — the breaker remains functional down to -25 °C without auxiliary heaters.
Coordination and application notes
The 10 000 mechanical endurance cycles (latching) reflect a switchgear-duty breaker designed for infrequent switching — it is a distribution protector, not a motor-switching contactor. For applications requiring regular load-break switching, pair it with a separate contactor or switch-disconnect ahead of the load. If remote monitoring or ground-fault protection is needed, specify the 3VA2 with the appropriate ETU or communication module — this is a base line-protection unit.