Siemens SENTRON 3WL10 - Isolating Distances and Insulating Equipment

For the withdrawable breaker, two alternatives are possible to achieve continuity and
equipotentiality of the grounding between the circuit breaker and the protection circuit of
the switchboard:
• Connection of the guide frame to the protection circuit with a cable in accordance with
IEC61439‑1, Section10.5.2
• If a conductive connection between the guide frame and the grounding of the switchboard
is ensured via the metal base (󹪞oor mounting) or the metal wall (wall mounting) of the
switchboard panel, no additional grounding is required. This means there must be no
insulation material between the circuit breaker and the grounded metal of the switchboard
panel.
4.2.2 Isolating distances and insulating equipment
When live parts are installed, the following rules must be followed:
• Minimum isolating distance between the phases:
Rated insulation voltage U
i
Smallest distance
1000 V acc. to IEC 61439: 14 mm
Siemens recommendation: 25 mm
• Isolating distances within the switchboard panel
To observe the isolating distances inside the panel, the following minimum dimensions for
the interior of the panel must be observed:
 A
3-pole
B
4-pole
C D
$
%
&
'
Fixed-
mounted
breaker
250 mm 322 mm ≤ 440 V: 332.5 mm
> 440 V: 382.5 mm
130 mm
Withdrawa‐
ble breaker
280 mm 350 mm ≤ 440 V: 390 mm
> 440 V: 440 mm
252 mm
Insulating measures
Note
The insulating equipment is only required for the 󹪝xed-mounted version of the circuit breaker.
No insulating equipment is required in the withdrawable breaker.
Application planning
4.2Power supply, grounding, and connection
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
Equipment Manual, 10/2023, L1V30499596002-03 147