Ac Voltage Input; Logic Inputs - GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual

3 INSTALLATION
The 745 has one voltage divider type input for AC voltages. There are no internal fuses or ground connections. Voltage
transformers up to a maximum 5000:1 ratio may be used. The nominal secondary voltage must be in the 60 to 120 V range.
Correct polarity must be observed for all logic input connections or equipment damage may result.
CAUTION
External contacts can be connected to the 16 logic inputs. As shown, these contacts can be either dry or wet. It is also pos-
sible to use a combination of both contact types.
A dry contact has one side connected to Terminal D11. This is the +32 V DC voltage rail. The other side is connected to the
required logic input terminal. When a dry contact closes, a 2.2 mA current flows through the associated circuit.
A wet contact has one side connected to the positive terminal of an external DC power supply. The other side is connected
to the required logic input terminal. In addition, the negative side of the external source must be connected to the relay DC
NEGATIVE rail at terminal D12. The maximum external source voltage for this arrangement is 300 V DC.
Dry Contact Connection
Logic Input 1
DC Negative
GE Multilin
Courtesy of NationalSwitchgear.com
Figure 3–9: ZERO-SEQUENCE (CORE BALANCE) CT INSTALLATION
745 RELAY
+32 V DC
D11
D1
32 V DC
D12
Figure 3–10: DRY AND WET CONTACT CONNECTIONS
745 Transformer Management Relay
Wet Contact Connection
745 RELAY
D11
+32 V DC
Logic Input 1 D1
32 V DC
DC Negative
D12
3.2 TYPICAL WIRING

3.2.6 AC VOLTAGE INPUT

3.2.7 LOGIC INPUTS

30 to 300 V DC
LOGICIN.CDR
3-9
3