Logic Diagrams - GE 850 Instruction Manual

CHAPTER 4: ABOUT SETPOINTS

Logic Diagrams

850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
Refer to the logic diagrams provided for a complete understanding of the operation of
each feature. These sequential logic diagrams illustrate how each setpoint, input
parameter, and internal logic is used in a feature to obtain an output. In addition to these
logic diagrams, the Setpoints chapter provides written descriptions for 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.
• Comparator 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 a setpoint and input parameter is indicated by the following
symbols: "<" (less than), ">" (greater than), etc.
• Pickup and Dropout Time Delays: Shown as a block with indication of two timers –
the t (Pickup Delay), and t
PKP
• LED Indicators: Shown as the following schematic symbol (X).
• Logic: Described with basic logic gates (AND, OR, XOR, NAND, NOR). The inverter
(logical NOT), is shown as a circle: O
• FlexLogic operands: Shown as a block with a heading labeled 'FLEXLOGIC OPERANDS'.
Each feature produces output flags (operands) which can be used further for creating
logic in the FlexLogic equation editor, or Trip Bus, or can be directly assigned to trigger
an output. The operands from all relay features constitute the list of FlexLogic
operands.
(Dropout Delay).
DPO
LOGIC DIAGRAMS
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