Table 2-5: Magnet Moving Metal Requirements
Steel Objects Category Definition Of Distance Location Minimum Distance Radial X Axial ft (m)
See Note 1
Objects 100 - 400 lbs distance from isocenter radial x axial (See Note 1) 3 Gauss line
Cars, Minivans, Vans, Pickup Trucks,
Ambulances
distance from isocenter measured to center of driving or
parking lane radial x axial (See Note 1)
15.5 x 21 (4.72 x 6.40)
Bus, Trucks (Utility, Dump, Semi) distance from isocenter measured to center of driving or
parking lane radial x axial (See Note 1)
18.1 x 24.5 (5.52 x 7.47)
Objects > 400 lbs, Elevators, Trains,
Subways
Place a directional probe (e.g. flux gate sensor) at isocen‐
ter of proposed magnet location aligned along the Z-axis.
Measure p-p magnetic field change (dc).
See Illustration 2-9 and see Example in
Note 2
Notes
1. Radial distances are magnet X and Y axis. Axial distances are magnet Z axis.
2.
EXAMPLE: For Moving Metal Requirements of objects > 400 lbs category you can use the time history of the occurrence to determine
what milligauss level to use.
a. If the site has elevators/counter weights near the magnet and the elevator can stop on the floors for longer than 20 seconds (which
is usually the case), peak-to-peak milligauss reading must be less than 4.43.
b.
If the site has a subway nearby and the field disturbance is less than 5 seconds, the peak-to-peak milligauss reading must be less
than 8.39.
c. Use 4.43 milligauss peak-to-peak.
SIGNA Voyager Pre-Installation
Direction 5680008–1EN, Revision 2
Chapter 2 General System Level 35
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