GE C60, Instruction Manual

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5-156 C60 Breaker Protection System GE Multilin
5.5 FLEXLOGIC 5 SETTINGS
5
5.5.3 FLEXLOGIC EVALUATION
Each equation is evaluated in the ascending order in which the parameters have been entered.
FlexLogic provides built-in latches that by definition have a memory action, remaining in the set state after the set
input has been asserted. These built-in latches are reset dominant, meaning that if logical "1" is applied to both set
and reset entries simultaneously, then the output of the latch is logical "0." However, they are volatile, meaning that
they reset upon removal of control power.
When making changes to FlexLogic entries in the settings, all FlexLogic equations are re-compiled whenever any
new FlexLogic entry value is entered, and as a result of the re-compile all latches are reset automatically.
5.5.4 FLEXLOGIC EXAMPLE
This section provides an example of implementing logic for a typical application. The sequence of the steps is quite impor-
tant as it should minimize the work necessary to develop the relay settings. Note that the example presented in the figure
below is intended to demonstrate the procedure, not to solve a specific application situation.
In the example below, it is assumed that logic has already been programmed to produce virtual outputs 1 and 2, and is only
a part of the full set of equations used. When using FlexLogic, it is important to make a note of each virtual output used – a
virtual output designation (1 to 96) can only be properly assigned once.
Figure 5–55: EXAMPLE LOGIC SCHEME
1. Inspect the example logic diagram to determine if the required logic can be implemented with the FlexLogic operators.
If this is not possible, the logic must be altered until this condition is satisfied. Once this is done, count the inputs to
each gate to verify that the number of inputs does not exceed the FlexLogic limits, which is unlikely but possible. If the
number of inputs is too high, subdivide the inputs into multiple gates to produce an equivalent. For example, if 25
inputs to an AND gate are required, connect Inputs 1 through 16 to AND(16), 17 through 25 to AND(9), and the outputs
from these two gates to AND(2).
Inspect each operator between the initial operands and final virtual outputs to determine if the output from the operator
is used as an input to more than one following operator. If so, the operator output must be assigned as a virtual output.
For the example shown above, the output of the AND gate is used as an input to both OR#1 and Timer 1, and must
therefore be made a virtual output and assigned the next available number (i.e. Virtual Output 3). The final output must
also be assigned to a virtual output as virtual output 4, which will be programmed in the contact output section to oper-
ate relay H1 (that is, contact output H1).
NOTE
LATCH
CONTACT INPUT H1c
State=Closed
XOR
AND
Reset
Set
VIRTUAL OUTPUT 2
State=ON
VIRTUAL INPUT 1
State=ON
DIGITAL ELEMENT 1
State=Pickup
DIGITAL ELEMENT 2
State=Operated
OR #2
Operate Output
Relay H1
OR #1
(800 ms)
Timer 1
Time Delay
on Pickup
(200 ms)
Timer 2
Time Delay
on Dropout
VIRTUAL OUTPUT 1
State=ON
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