L Ogic D Iagrams - GE 750 Instruction Manual

OVERVIEW
5.1.5 Logic Diagrams
5 - 8
The logic diagrams provided should be referred to for 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 a 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 location of
setpoints is indicated by the path heading on the diagram. 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.
• Measurement Units: 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.
Relationship between setpoint and input parameter is indicated by the following
symbols: "<" (less than), ">" (greater than), etc. The ANSI device number (if one exists) is
indicated above the block.
• Time Delays: Shown as a block with the following schematic symbol: |———|. If delay is
adjustable, associated delay setpoint is shown directly above, and schematic symbol
has an additional variability indication, an oblique bar. ANSI device number (62) is
indicated above the 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: .
• Conditions: Shown as a rounded block with a shaded heading labeled 'CONDITION'.
Conditions are mutually exclusive, i.e., only one condition can be active at any point in
time. Conditions latch until another condition becomes active. The output of an active
condition is 1 or logic high.
CHAPTER 5: SETPOINTS
750 FEEDER MANAGEMENT RELAY – INSTRUCTION MANUAL