4–98
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
INPUTS
CHAPTER 4: SETPOINTS
Analog Inputs
The 8 Series relay can monitor any external quantity from the DcmA transducers such as
vibration, field current, pressure, tap position etc., using ‘Analog Inputs’. Any one of the
standard transducer output ranges: 0 to 1 mA, 0 to 5 mA, 0 to 10mA, 0 to 20 mA, or 4 to 20
mA can be connected to the Analog Input terminals. 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 is used for the
three circuits. Transducers limit this isolation to ±36 V with respect to the 8 Series safety
ground.
Depending upon the order code, the 8 Series relay supports one optional DC analog card.
The analog card has 4 analog inputs and 7 analog outputs. For each element, when the
measured analog input quantity exceeds the Pickup level for longer than the associated
time delay, the relay can be configured to cause an alarm, or trip. The element will drop
out only when the user programmed Dropout ratio has been met.
NOTE
NOTE:
The connected analog input is still read and displayed in METERING /ANALOG INPUTS if the
trip function or alarm function is set to “Disabled”, and the Analog Input is not Disabled.
Path
:
Setpoints > Inputs > Analog Inputs > Analog In 1(X) Setup
Settings
FUNCTION
Range: Disabled, Enabled, Bearing Vibration, Excitation Current
Default: Disabled
This setting disables the Analog Input function or enables it for any generic application
or any specific application such as Bearing Vibration or Excitation Current. Upon
selecting a specific application, its value is also displayed in the Generator metering
menu.
NAME
Range: Any combination of 13 Characters
Default: Anlp 1
This setting allows the user to give a symbolic name to each analog input. The length is
limited to 13 characters.
UNITS
Range: Any combination of 6 Characters
Default: units
This setting allows the user to give a symbolic name to the engineering units. The length
is limited to 6 characters.
RANGE
Range: 0 to 1 mA, 0 to 5 mA, 0 to 10 mA, 0 to 20 mA, 4 to 20 mA
Default: 0 to 1 mA
This setting provides the selection for the analog input range.
MIN VALUE
Range: -500000 to 500000 units in steps of 1 unit
Default: 0
For the MINIMUM VALUE setpoint, enter the value which corresponds to the minimum
output value of the transducer. For example, if a temperature transducer which outputs
4 to 20 mA for temperatures 0 to 250°C is connected to the analog input, then enter “0”
for the MINIMUM VALUE. The relay then interprets 4 mA as representing 0°C.
Intermediate values between the minimum and maximum are scaled linearly.
