Voltage Inputs; Digital Inputs; Analog Inputs - GE Multilin 489 Instruction Manual

3.2.5

Voltage Inputs

3.2.6

Digital Inputs

3.2.7

Analog Inputs

3–14
Courtesy of NationalSwitchgear.com
The 489 has four voltage transformer inputs, three for generator terminal voltage and one
for neutral voltage. There are no internal fuses or ground connections on the voltage
inputs. The maximum phase VT ratio is 300.00:1 and the maximum neutral VT ratio is
240.00:1. The two possible VT connections for generator terminal voltage measurement
are open delta or wye (see Typical Wiring Diagram on page 3–10). The voltage channels are
connected in wye internally, which means that the jumper shown on the delta-source
connection of the Typical Wiring Diagram, between the phase B input and the 489 neutral
terminal, must be installed for open delta VTs.
Polarity of the generator terminal VTs is critical for correct power measurement and
voltage phase reversal operation.
There are 9 digital inputs that are designed for dry contact connections only. Two of the
digital inputs, Access and Breaker Status have their own common terminal, the balance of
the digital inputs share one common terminal (see Typical Wiring Diagram on page 3–10).
In addition, the +24 V DC switch supply is brought out for control power of an inductive or
capacitive proximity probe. The NPN transistor output could be taken to one of the
assignable digital inputs configured as a counter or tachometer. Refer to the Specifications
section of this manual for maximum current draw from the +24 V DC switch supply.
DO NOT INJECT VOLTAGES TO DIGITAL INPUTS. DRY CONTACT CONNECTIONS ONLY.
Terminals are provided on the 489 for the input of four 0 to 1 mA, 0 to 20 mA, or 4 to 20 mA
current signals (field programmable). This current signal can be used to monitor any
external quantity such as: vibration, pressure, field current, etc. The four inputs share one
common return. Polarity of these inputs must be observed for proper operation The analog
input circuitry is isolated as a group with the Analog Output circuitry and the RTD circuitry.
Only one ground reference should be used for the three circuits. Transorbs limit this
isolation to ±36 V with respect to the 489 safety ground.
In addition, the +24 V DC analog input supply is brought out for control power of loop
powered transducers. Refer to the Specifications section of this manual for maximum
current draw from this supply.
CHAPTER 3: INSTALLATION
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL