GE C30 Instruction Manual page 235

CHAPTER 5: SETTINGS
scheme where a contact input is used to block an element is wanted, this selection is made when programming the
element. This capability also applies to the other features that set flags: elements, virtual inputs, remote inputs, schemes,
and human operators.
If more complex logic than shown in the figure is required, it is implemented via FlexLogic. For example, to have the closed
state of contact input H7a and the operated state of the phase undervoltage element block the operation of the phase
time overcurrent element, the two control input states are programmed in a FlexLogic equation. This equation ANDs the
two control inputs to produce a virtual output that is then selected when programming the phase time overcurrent to be
used as a blocking input. Virtual outputs can only be created by FlexLogic equations.
Traditionally, protective relay logic has been relatively limited. Any unusual applications involving interlocks, blocking, or
supervisory functions had to be hard-wired using contact inputs and outputs. FlexLogic minimizes the requirement for
auxiliary components and wiring while making more complex schemes possible.
The logic that determines the interaction of inputs, elements, schemes, and outputs is field-programmable through the use
of logic equations that are sequentially processed. The use of virtual inputs and outputs in addition to hardware is
available internally and on the communication ports for other relays to use (distributed FlexLogic).
FlexLogic allows users to customize the relay through a series of equations that consist of operators and operands. The
operands are the states of inputs, elements, schemes, and outputs. The operators are logic gates, timers, and latches (with
set and reset inputs). A system of sequential operations allows any combination of operands to be assigned as inputs to
specified operators to create an output. The final output of an equation is a numbered register called a virtual output.
Virtual outputs can be used as an input operand in any equation, including the equation that generates the output, as a
seal-in or other type of feedback.
A FlexLogic equation consists of parameters that are either operands or operators. Operands have a logic state of 1 or 0.
Operators provide a defined function, such as an AND gate or a Timer. Each equation defines the combinations of
parameters to be used to set a Virtual Output flag. Evaluation of an equation results in either a 1 (=ON, or flag set) or 0
(=OFF, or flag not set). Each equation is evaluated at least four times every power system cycle.
Some types of operands are present in the relay in multiple instances, for example contact and remote inputs. These types
of operands are grouped together (for presentation purposes only) on the faceplate display. The table lists characteristics
of the different types of operands.
Table 5-15: C30 FlexLogic operand types
Operand type State
Contact Input On
Off
Contact Output Current On
(type Form-A contact
Voltage On
only)
Voltage Off
Direct Input On
Element Pickup
(Digital)
Dropout
Operate
Element Higher than
(Digital Counter)
Equal to
Lower than
Fixed On
Off
C30 CONTROLLER SYSTEM – INSTRUCTION MANUAL
Example of format Characteristics
[Input Is '1' (= ON) if...]
Cont Ip On Voltage is applied presently to the input (external contact
closed)
Cont Ip Off Voltage is not applied presently to the input (external
contact open)
Cont Op 1 Ion Current is flowing through the contact
Cont Op 1 VOn Voltage exists across the contact
Cont Op 1 VOff Voltage does not exist across the contact
DIRECT INPUT 1 On The direct input is presently in the ON state
Dig Element 1 PKP The input operand is at logic 1
Dig Element 1 DPO This operand is the logical inverse of the above PKP
operand
Dig Element 1 OP The input operand has been at logic 1 for the programmed
pickup delay time, or has been at logic 1 for this period and
is now at logic 0 but the reset timer has not finished timing
Counter 1 HI The number of pulses counted is above the set number
Counter 1 EQL The number of pulses counted is equal to the set number
Counter 1 LO The number of pulses counted is below the set number
On Logic 1
Off Logic 0
FLEXLOGIC
5
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