CHAPTER 5: DEVICE, SYSTEM, INPUT AND OUTPUT SETPOINTS SYSTEM
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 5–65
System
Figure 5-13: System Display Hierarchy
Current Sensing
The Current Sensing menu provides the setup menu for the Current Transformers (CTs)
connected to the 850
terminals. The setup of the three-phase CTs, the Ground CT, and the
Sensitive Ground CT requires a selection of primary CT ratings. The secondary CT ratings
are selected in the 850
Order code. The basic AC card has two AC banks, definable at the
time of ordering the relay with one bank currents and one bank voltages.
The 850-E Feeder Protection System has three inputs for phase currents A, B, and C, and
one input for ground/residual current, all in slot J.
The 850-D Dual Feeder Protection System has two three-phase currents, and one input for
ground/residual current in slots J and K respectively.
The 850-P Multi Feeder Protection System supports up to four three-phase currents in slots
J and K.
The single AC input from the card inserted in slot K for 850-D and 850-E is used to connect
to the sensitive ground CT for measuring small currents which cannot be correctly
measured by a standard type of current input.
The Current sensing selection for the 850 is organized in a menu as shown:
Path: Setpoints > System > Current Sensing > CT Bank 1-J1
CT BANK NAME
Range: up to 13 alphanumeric characters
Default: CT Bank 1-J1
The name entered here is displayed in the Signal Input setpoint for applicable functions,
and in the Metering menu.
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