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 specified 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 out-
put. 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 parame-
ters to be used to set a Virtual Output flag. Evaluation of an equation results in either a 1 (=ON, i.e. flag set) or 0 (=OFF, i.e.
flag not set). Each equation is evaluated at least 4 times every power system cycle.
Some types of operands are present in the relay in multiple instances; e.g. contact and remote inputs. These types of oper-
ands are grouped together (for presentation purposes only) on the faceplate display. The characteristics of the different
types of operands are listed in the table below.
Table 5–7: C30 FLEXLOGIC™ OPERAND TYPES
(type Form-A contact
[INPUT IS '1' (= ON) IF...]
Cont Ip On
Voltage is presently applied to the input (external contact
Cont Ip Off
Voltage is presently not applied to the input (external
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 exists 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
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.
REMOTE INPUT 1 On
The remote input is presently in the ON state.
Virt Ip 1 On
The virtual input is presently in the ON state.
Virt Op 1 On
The virtual output is presently in the set state (i.e.
evaluation of the equation which produces this virtual
output results in a "1").
C30 Controller System