ABB Relion 670 Series Technical Reference Manual page 142

Section 5
Differential protection
136
for input TRZONE). It operates when external trip signal is given to this bay
(see description for input TRBAY).
• CONNZA, this binary output has logical value one whenever this bay CT is
connected to zone A
• CONNZB, this binary output has logical value one whenever this bay CT is
connected to zone B
• CONNBAY, this is not a binary output. It has integer value between 1 and 9
and is used in order to display actual "BayConnections" information on the
local HMI.
Settings
• BAYnn, this setting is only a string with user definable free, descriptive text to
designate particular primary bay in the station in order to make easier bay
identification on the BayConnections matrix on the local HMI. The string can
be up to thirteen characters long.
• CTConnection, this setting determines how the hardware CT input is
connected to bay function block in software. One of the following three
alternatives shall be selected for every function block:
1. NotConnected, when this mode is selected the hardware CT input is
disconnected from the bay function block in software. This setting shall
be used for spare CT inputs in the IED or for a CT inputs where only for
example, breaker failure protection is required (that is, for middle
breaker in one and half breaker configuration)
2. Connected, when this mode is selected the hardware CT input is
connected to the bay function block in software. This is normal setting
for a CT input which is used for busbar protection
3. Conn Inverted, when this mode is selected the hardware CT input is
connected to the bay function block in software, but the CT current is
inverted (that is, multiplied with –1). This is used only in special
applications.
• ZoneSel, this setting determines how the bay CT input connection to the
differential zones is controlled within the IED internal logic. One of the five
alternatives listed below shall be selected for every function block.
CtrlIncludes and CtrlExcludes are typically used for feeder bays in double
busbar-single breaker stations where dynamic connections between CT and
differential zones are required. It shall be noted that when one of the last two
modes are selected and in the same time the operation of the Zone
Interconnection function block is set to "On" the zone interconnection (that is,
merging between ZA & ZB) will be automatically started as soon as the bay is
connected to both zones simultaneously (that is, zone interconnection on a
feeder bay).
1. FixedToZA, when this mode is selected the bay CT input is always
connected to the differential zone A. This is for example used for simple
busbar configurations where dynamic connections between CTs and
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