System - GE 869 Instruction Manual

SYSTEM

System
Current Sensing
4–68
Figure 4-15: System Display Hierarchy
The Current Sensing menu provides the setup menu for the Current Transformers (CTs)
connected to the 869 terminals. The setup of the three-phase CTs, and the Ground CT
requires a selection of primary CT ratings. The secondary CT ratings are selected in the
869 Order code. The CT inputs are grouped in banks of four currents on the 869 – three
inputs for phase currents A, B, and C, and one input for ground current. The basic AC card
has two AC banks, one bank currents and one bank voltages.
The 869 basic Motor Protection System has 8 AC inputs, which reside on the card inserted
in slot J.
There are two options for the 8 AC inputs from card J and they are as follows:
Option 1 (P5G5/P1G1):
• four AC input currents, 3 CTs for phase currents and 1 CT for the ground or residual
connection current, and
• four AC input voltages, 3 VTs for phase voltages, and 1 VT for auxiliary voltage
Option 2 (P50B/P10B):
• four AC input currents, 3 CTs for phase currents and 1 Sensitive 50:0.025A CT for
ground or residual connection current, and
• four AC input voltages, i.e. 3 VTs for phase voltages, and 1 VT for auxiliary voltage
Additionally, a second card can be inserted into slot K. It has four AC input currents, i.e. 3
CTs for phase currents and/or 1 CT for the sensitive 50:0.025A ground current.
The Current sensing selection for the 869 is organized in the menu path as shown:
Path:
Setpoints > System > Current Sensing > CT Bank 1-J1
Path:
Setpoints > System > Current Sensing > CT Bank 2-K1
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS