11 Technical data
Maschinenfabrik Reinhausen GmbH 2019
74
6107891/02 EN
ECOTAP
®
VPD
®
11.5 Tapped winding potential connection
During its switching operation the tap winding is briefly electrically isolated
from the main winding by the reversing change-over selector or coarse
change-over selector. It then adopts a potential resulting from the voltages of
the adjacent windings and coupling capacities for these windings or earthed
parts.
This potential shift of the tap winding produces corresponding voltages be-
tween the deactivating change-over selector contacts because one contact
is always connected to the tap winding and the other contact is always con-
nected to the main winding. This voltage is known as the recovery voltage
U
W
.
When separating the change-over selector contacts, a capacitive current has
to be interrupted. This current depends on the aforementioned coupling ca-
pacities of the tap winding. This current is known as the breaking current I
S
.
The recovery voltage U
W
and breaking current I
S
may result in impermissible
signs of discharge on the change-over selector. The permissible recovery
voltage U
W
and breaking current I
S
ranges are listed below.
Maximum permissible values for recovery voltage U
W
and breaking
current I
S
Figure 40: Recovery voltage U
W
and breaking current I
S
