GE L90 Instruction Manual page 97

5 SETTINGS 5.1 OVERVIEW
c) CT/VT INPUT CHANNEL CONFIGURATION
Upon relay startup, configuration settings for every bank of current or voltage input channels in the relay are automatically
generated from the order code. Within each bank, a channel identification label is automatically assigned to each bank of
channels in a given product. The 'bank' naming convention is based on the physical location of the channels, required by
the user to know how to connect the relay to external circuits. Bank identification consists of the letter designation of the slot
in which the CT/VT module is mounted as the first character, followed by numbers indicating the channel, either 1 or 5.
For three-phase channel sets, the number of the lowest numbered channel identifies the set. For example, F1 represents
the three-phase channel set of F1/F2/F3, where F is the slot letter and 1 is the first channel of the set of three channels.
Upon startup, the CPU configures the settings required to characterize the current and voltage inputs, and will display them
in the appropriate section in the sequence of the banks (as described above) as follows for a maximum configuration: F1,
F5, L1, L5, S1, and S5.
The above section explains how the input channels are identified and configured to the specific application instrument
transformers and the connections of these transformers. The specific parameters to be used by each measuring element
and comparator, and some actual values are controlled by selecting a specific source. The source is a group of current and
voltage input channels selected by the user to facilitate this selection. With this mechanism, a user does not have to make
multiple selections of voltage and current for those elements that need both parameters, such as a distance element or a
watt calculation. It also gathers associated parameters for display purposes.
The basic idea of arranging a source is to select a point on the power system where information is of interest. An applica-
tion example of the grouping of parameters in a Source is a transformer winding, on which a three phase voltage is mea-
sured, and the sum of the currents from CTs on each of two breakers is required to measure the winding current flow.
5
GE Multilin L90 Line Differential Relay 5-7