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OS32C
User’s Manual
Chapter7
Appendix
E
Additional Zone Set Switching Strategies
The following information provides additional strategies to specify protection zones that guarantee protection
of zone set A when zone set may switch before monitoring of zone set A is no longer required when switching
from zone set A to zone set B (t
EndZoneA). These examples focus on the dangerous area that exists during zone
set transitions, limiting the extended protection zone Z
extra to only the areas that need it as opposed to a
general extension as described in section 2.
The following diagram uses the same example zone set layout as in the example in section 2, Fig. 2-12.
Based on transition related timing parameters previously discussed, this diagram identifies the actual
remaining danger area during zone set switching (during T
extend).
The danger area identified in this diagram is only for example, the actual shape of the danger area will vary based on the
installation.
Fig. 7-7 Danger area during zone set switching
There are 3 options for ensuring the Danger Area is adequately guarded during the transition, described in the
following examples.
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