CHAPTER 3: INSTALLATION
WIRING
L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL
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CT/VT modules can be ordered with a standard ground current input that is the same as the phase current input. Each AC
current input has an isolating transformer and an automatic shorting mechanism that shorts the input when the module is
withdrawn from the chassis. There are no internal ground connections on the current inputs. Current transformers with 1
to 50000 A primaries and 1 A or 5 A secondaries can be used.
These modules have enhanced diagnostics that can automatically detect CT/VT hardware failure and take the relay out of
service.
CT connections for both ABC and ACB phase rotations are identical, as shown in the Typical Wiring Diagram.
The phase voltage channels are used for most metering and protection purposes. The auxiliary voltage channel is used as
input for the synchrocheck and volts-per-hertz features, which are optional features for some UR models.
The L60 uses a special CT/VT module not available on other UR-series relays. This type 8P module has four current inputs
and special communications inputs/outputs for interfacing with power line carriers (PLCs). The communications interface
requires an external DC source (station battery) to drive inputs/outputs as shown in the L60 Channel Communications
section in this chapter.
Figure 3-16: CT/VT module wiring
3.3.5 Contact inputs and outputs
Nearly all contact input/output modules have 24 terminal connections. The connections are arranged typically as three
terminals per row, with eight rows in total. A given row of three terminals can be used for the outputs of one relay. For
example, for form-C relay outputs, the terminals connect to the normally open (NO), normally closed (NC), and common
contacts of the relay. For a form-A output, there are options of using current or voltage detection for feature supervision,
depending on the module ordered. The terminal configuration for contact inputs is different for the two applications.
The contact inputs are grouped with a common return. The input/output modules have three versions of grouping: four
inputs per common return, five inputs per common return on a high-density module, and two inputs per common return.
When a contact input/output module is ordered, four inputs per common is used. If the inputs must be isolated per row,
then two inputs per common return are selected (4D module). If the space limitation in the relay requires use of a high-
density input module (6W), five inputs share one common return and the module has six banks of inputs.
Substitute the tilde “~” symbol with the slot position of the module in the following figure.
