b) CT/VT MODULE CONFIGURATION
CT and VT input channels are contained in CT/VT modules. The type of input channel can be phase/neutral/other voltage,
phase/ground current, or sensitive ground current. The CT/VT modules calculate total waveform RMS levels, fundamental
frequency phasors, symmetrical components and harmonics for voltage or current, as allowed by the hardware in each
channel. These modules may calculate other parameters as directed by the CPU module.
A CT/VT module contains up to eight input channels, numbered 1 through 8. The channel numbering corresponds to the
module terminal numbering 1 through 8 and is arranged as follows: Channels 1, 2, 3 and 4 are always provided as a group,
hereafter called a "bank," and all four are either current or voltage, as are channels 5, 6, 7 and 8. Channels 1, 2, 3 and 5, 6,
7 are arranged as phase A, B and C respectively. Channels 4 and 8 are either another current or voltage.
Banks are ordered sequentially from the block of lower-numbered channels to the block of higher-numbered channels, and
from the CT/VT module with the lowest slot position letter to the module with the highest slot position letter, as follows:
INCREASING SLOT POSITION LETTER -->
CT/VT MODULE 1
CT/VT MODULE 2
< bank 1 >
< bank 3 >
< bank 2 >
< bank 4 >
The UR platform allows for a maximum of three sets of three-phase voltages and six sets of three-phase currents. The
result of these restrictions leads to the maximum number of CT/VT modules in a chassis to three. The maximum number of
sources is six. A summary of CT/VT module configurations is shown below.
CT Bank (3 phase channels, 1 ground channel)
VT Bank (3 phase channels, 1 auxiliary channel)
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. See
the HardFiber instruction manual for designations of HardFiber voltage and current banks.
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.
CT/VT MODULE 3
< bank 5 >
< bank 6 >
L60 Line Phase Comparison System