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CHAPTER 4: SETPOINTS
Common Setpoints
NOTE:
NOTE
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
To make the application of this device as simple as possible, similar methods of operation
and similar types of setpoints are incorporated in various features. Rather than repeat
operation descriptions for this class of setpoint throughout the manual, a general
description is presented in this overview. Details that are specific to a particular feature are
included in the discussion of the feature. The form and nature of these setpoints is
described below.
•
FUNCTION setpoint: The
operational characteristic of each feature. The range for this setpoint is: "Disabled",
"Trip", "Alarm", "Latched Alarm", and "Configurable".
If the FUNCTION setpoint is selected as "Disabled", then the feature is not operational.
If the FUNCTION setpoint is selected as "Trip", then the feature is operational. When
the "Trip" function is selected and the feature operates, the output relay #1 "Trip"
operates, and the LED "TRIP" is lit.
If the FUNCTION setpoint is selected as "Alarm" or "Latched Alarm", then the feature is
operational. When this function is selected, and the feature operates, the LED "ALARM"
is lit, and any assigned auxiliary output relay operates. The "Trip" output relay does
not operate, and the LED "TRIP" is not lit.
When Alarm function is selected and the feature operates, the LED "ALARM" flashes,
and it self-resets when the operating conditions are cleared.
When Latched Alarm function is selected, and the feature operates, the LED "ALARM"
will flash during the operating condition, and will be steady lit after the conditions are
cleared. The LED "ALARM" can be reset by issuing reset command.
If the FUNCTION setpoint is selected as "Configurable", the feature is fully operational
but outputs are not driving any action, such as output relay #1, Alarm LED or anything
else. The User has to program operands from this element to a desirable action which
may be the auxiliary output relay from the list of available relays in the element itself,
Flexlogic, Trip Bus etc.
The FlexLogic operands generated by the operation of each feature are active, and
available to assign to outputs, or use in FlexLogic equations, regardless of the selected
function, except when the function is set to "Disabled".
•
PICKUP: The setpoint selects the threshold equal to or above (for over elements) or
equal to or below (for under elements) which the measured parameter causes an
output from the measuring element.
•
PICKUP DELAY: The setpoint selects a fixed time interval to delay an input signal from
appearing as an output.
•
DROPOUT DELAY: The setpoint selects a fixed time interval to delay dropping out the
output signal after being generated.
•
TDM: The setting provides a selection for Time Dial Multiplier which modifies the
operating times per the selected inverse curve. For example, if an IEEE Extremely
Inverse curve is selected with TDM=2, and the fault current is 5 times bigger than the
PKP level, operation of the element can not occur before an elapsed time of 2.59 s
from Pickup.
•
OUTPUT RELAYS: The
<ELEMENT_NAME> RELAYS
operate when the feature generates an output. The range is any combination of the
Auxiliary output relays. The letter "X" denotes the number of auxiliary output relays
defined for the relay's order code.
•
DIRECTION: The
<ELEMENT_NAME> DIRECTION
features which are subject to control from a directional element. The range is
"Disabled", "Forward", and "Reverse". If set to "Disabled", the element is allowed to
operate for current flow in any direction. There is no supervision from the directional
<ELEMENT_NAME> FUNCTION
setpoint selects the relays required to
setpoint is available for overcurrent
SETPOINTS MAIN MENU
setpoint determines the
4–3
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