Beckhoff EL72 1-901 Series Manual page 52

Installation
Fig. 39: Note
Background
A current-carrying conductor generates a magnetic field around it according to
B = µ * I / (2π * d)
0
with
B [Tesla] magnetic field
-7
µ0 = 4*π*10 [H/m] (assumption: no magnetic shielding)
I [A] current
d [m] distance to conductor
Interference from external magnetic fields
The magnetic field strength should not exceed a permitted level all around the device.
In practice this equates to a recommended minimum distance between a conductor and the device
surface as follows:
- Current 10 A: 12 mm
- Current 20 A: 25 mm
- Current 40 A: 50 mm
Unless specified otherwise in the device documentation, stringing together modules (e.g. terminal
blocks based on a 12 mm grid) of same type (e.g. EL2212-0000) is permitted.
52 Version: 1.9 EL72x1-901x