ABB Relion 650 Series Applications Manual page 75

1MRK 505 287-UUS B
the circuit. A time delay of a few seconds is used before the shorting and alarm are activated.
Auxiliary relays with contacts that can withstand high voltage shall be used, like RXMVB types.
IEC05000749 V1 EN-US
Figure 27: Current voltage characteristics for the non-linear resistors, in the range 10-200 V, the average
range of current is: 0.01–10 mA
6.1.3.5 Double busbar applications
In double busbar applications, the CTs shall be connected to the right protection zone according
to the position of the disconnectors.
Normally, open (early closing) auxillary contacts of the disconnectors shall be used to energize
auxillary relays which perform the CT switching; these auxillary relays shall have contacts which
withstand high voltage, like RXMVB type.
In this application, the use of check zone is recommended; the third zone available in REB650 can
be used as check zone.
Separate CT cores shall be used for check zone.
Busbar protection REB650
Application manual
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Section 6
Differential protection
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