Specifications

B-field Exposure From Induction Cooking Appliances 41
6 Worst-Case Exposure Conditions for Varied Loading of the
Induction Cookers
The influence of several parameters was evaluated to assess the worst-case exposure.
6.0.6 Predominant Parameters
Pot-hob centering The predominant parameter is the centering of the pot on the hob. The
B-field measured at a fixed position of the probe is minimal for perfect centering. However,
the B-field increases by factors of approximately 3, 15 and 10 when the pan is displaced by
8 cm for appliances 1, 2 and 3, respectively (see Figure 30). For non-centering by ±4 mm in
each direction, the B-field measured increases by approximately 2.5-4 %, 3-11 % and 5-10 % for
appliances 1, 2 and 3, respectively.
Figure 30: Pot-hob centering, a) appliance 1, b) appliance 2 and c) appliance 3. For
each appliance, pot 3 (large pot, standard set of pots) was centered on the largest hob (hobs
1, 2 and 1 for appliances 1, 2 and 3, respectively). The Narda probe measured the B-field at
a fixed position (front side of the appliance in front of the largest hob; measuring distance of
1 cm and heat setting 7 for appliances 1, 2 and 3). The pot was then displaced in the x and
y directions, and the corresponding B-field was measured (the probe remained fixed). Other
measuring conditions were according to EN50366.
Pot characteristics Other parameters leading to significant variation of the B-field include
the bottom diameter, shape, bottom flatness and material grade (see Figure 31). Generally, the
B-field measured increases with smaller bottom diameter, and it is larger when the pots are old
or not perfectly flat.
Single-hob versus multi-hob use Simultaneous operation of several hobs is possible with
appliances 1 and 2. This multi-hob use increases the total B-field exposure since the area of
exposition is enlarged (see 6.1). However, in single-hob as well as in multi-hob use the B-field
emitted by each hob is highly localized in the vicinity of the particular hob. Thus for multi-hob
use the maximum B-field is still localized in front of the largest hob. Moreover, for multi-hob use
it was found experimentally that the maximum B-field exposure does not necessarily correspond
to all four hobs switched on simultaneously. The maximum B-field exposure corresponding to