GE Multilin L90 Line Differential Relay 5-75 SETTINGS 5.1 OVERVIEW5c) CT/VT INPUT CHANNEL CONFIGURATIONUpon relay startup, configuration settings for every bank of current or voltage input channels in the relay are automaticallygenerated from the order code. Within each bank, a channel identification label is automatically assigned to each bank ofchannels in a given product. The ëbankí naming convention is based on the physical location of the channels, required bythe user to know how to connect the relay to external circuits. Bank identification consists of the letter designation of the slotin 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 representsthe 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 themin 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 instrumenttransformers and the connections of these transformers. The specific parameters to be used by each measuring elementand comparator, and some actual values are controlled by selecting a specific source. The source is a group of current andvoltage input channels selected by the user to facilitate this selection. With this mechanism, a user does not have to makemultiple selections of voltage and current for those elements that need both parameters, such as a distance element or awatt 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.
