lower than with the protection core. This should be taken into account
when setting the current circuit supervision function.
CCM
I_A
I_B
ALARM
FAIL
I_C
I_REF
BLOCK
protection relay
Core 1
(protection)
IL1
IL2
IL3
I_A
I_B
I_C
I_REF
Measurement device
Core 2
(measurement)
GUID-C5A6BB27-36F9-4652-A5E4-E3D32CFEA77B-ANSI V3 EN
Figure 439: Connection diagram for current circuit supervision with two sets of three-
phase current transformer cores (protection and measurement)
Example of incorrect connection
The currents must be measured with two independent cores, that is, the phase currents
must be measured with a different core than the reference current. A connection diagram
shows an example of a case where the phase currents and the reference currents are
measured from the same core.
1MAC059074-MB A Section 6
Supervision functions
615 series ANSI 851
Technical Manual
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