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CHAPTER 6: SETPOINTS
Logic diagrams
Setting text abbreviations
345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
•
DELAY setpoint: The
<ELEMENT_NAME> DELAY
to delay an input signal from appearing at the output. The time from a contact input
change of state or an AC parameter input level change to a contact closure of the 1
Trip relay, is the time selected as time delay in this setpoint plus approximately up to 2
power frequency periods.
•
DIRECTION setpoint: The
overcurrent 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. If set to "Forward", the element is allowed to operate for current
flow in the forward direction only, as determined by the directional element. If set to
"Reverse", the element is allowed to operate for current flow in the reverse direction
only, as determined by the directional element.
The logic diagrams provide a complete comprehensive understanding of the operation of
each feature. These sequential logic diagrams illustrate how each setpoint, input
parameter, and internal logic is used in the feature to obtain an output. In addition to these
logic diagrams, written descriptions are provided in the setpoints chapter which includes
each feature.
•
Setpoints: Shown as a block with a heading labeled 'SETPOINT'. The exact wording of
the displayed setpoint message identifies the setpoint. Major functional setpoint
selections are listed below the name and are incorporated in the logic.
•
Compensator Blocks: Shown as a block with an inset box labeled 'RUN' with the
associated pickup/dropout setpoint shown directly above. Element operation of the
detector is controlled by the signal entering the 'RUN' inset. The measurement/
comparison can only be performed if a logic '1' is provided at the 'RUN' input. The
relationship between setpoint and input parameter is indicated by the following
symbols: "<" (less than) " >" (greater than), etc.
•
Time Delays: Shown as a block with either pickup, drop-out, or both; times in
milliseconds or seconds. If the delay is adjustable, associated delay setpoint is shown
with block SETPOINT on the top of the delay block.
LED Indicators: Shown as the following schematic symbol, □. The exact wording of
•
the front panel label identifies the indicator.
•
Logic: Described with basic logic gates (AND, OR, XOR, NAND, NOR). The inverter
(logical NOT), is shown as a circle: ○.
The following abbreviations are used in the setpoints pages.
•
A: amperes
•
kA: kiloamperes
•
kV: kilovolts
•
MVA: mega-volt-amperes
•
AUX: auxiliary
•
COM, Comms: communications
•
CT: current transformer
•
GND: ground
•
Hz: Hertz
•
MAX: maximum
setpoint selects a fixed time interval
<ELEMENT_NAME> DIRECTION
SETPOINTS MAIN MENU
setpoint is available for
6–3
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