GE 745 Instruction Manual page 142

S4 ELEMENTS
5.6 S4 Elements
5.6.1 Introduction to Elements
5–46
Protection and monitoring elements are configured in this page. This includes complete
differential protection; phase, neutral, ground, negative sequence overcurrent; restricted
ground fault (differential ground); under, over, and rate-of-change of frequency;
overexcitation; harmonic monitoring; analog input monitoring; current demand
monitoring; and transformer overload monitoring.
Each element is comprised of a number of setpoints, some of which are common to all
elements. These common setpoints are described below, avoiding repeated descriptions
throughout this section:
<NAME OF ELEMENT>
FUNCTION: Enabled
<NAME OF ELEMENT>
RLYS (1-8):
<NAME OF ELEMENT>
TARGET: Latched
<NAME OF ELEMENT>
BLOCK: Disabled
Following the setpoint descriptions are logic diagrams illustrating how each setpoint, input
parameter, and internal logic is used in a feature to obtain an output. The logic diagrams
are organized into the following functional blocks:
Range: Disabled, Enabled
Select "Enabled" to enable the element. For critical protection
elements, this setpoint is normally "Enabled" except for test
purposes. For elements which are not to be used, this
setpoint should be set to "Disabled".
Range: 1 TO 8
Select output relay to be configured for the element.
Range: Self-reset, Latched, None
Target messages indicate which elements have picked up or
operated. Select "Latched" to keep the element target
message in the queue of target messages, even after the
condition which caused the element to operate has been
cleared, until a reset command is issued. Select "Self-reset" to
automatically remove the target message from the message
queue after the condition has been cleared. Select "None" to
inhibit the display of the target message when the element
operates. An element whose target type is "None" will never
disable the LED self-test feature because can not generate a
displayable target message.
Range: Disabled, Logc Inpt 1 to 16, Virt Inpt 1 to 16, Output
Rly 1 to 8, SelfTest Rly, Virt Outpt 1 to 5
Select any logic input, virtual input, output relay, or virtual
output which, when asserted or operated, blocks the element
from operating. Selecting a logic or virtual input allows
blocking the element based on a decision external to the 745.
Selecting an output relay or virtual output allows blocking the
element based on conditions detected by the 745 and the
combination of logic programmed in the associated
FlexLogic™ equation.
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS