2.10 Defrosting Protection
115
7ST6 Manual
E50417-G1176-C251-A3
Switching On/Off
and Blocking
The defrosting protection can be switched on/off via parameters, binary input or the
protocol of the system interface.
Also, the defrosting protection can be dynamically blocked via binary input or via pro-
tocol. The figure below shows the control logic:
Figure 2-33
Control logic of the defrosting protection
Pickup and TRIP
Command
A fault detected on the basis of the differential protection characteristic is signalled as
a pickup if the defrosting protection is switched on. The pickup is signalled with the
indication
„Defrost PICKUP“
, and the TRIP command
„Defrost TRIP“
is output
after the delay time
T ID>
if the pickup condition is still present and the defrosting pro-
tection is not blocked. The delay time allows to bridge transient compensation states
which occur on switching in the defrosting current, and which might for a short time
cause a pickup of the defrosting current.
Figure 2-34
Pick-up and tripping logic of the defrosting protection
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