P.14.7
Date Code 20151029 Protection Manual SEL-411L Relay
SELOGIC Control Equation Programming
SEL
OGIC Control Equation Setting Structure
There is a free-form SELOGIC control equation programming area associated
with protection. Because this area operates at the protection processing
interval along with protection algorithms and outputs, use this area to extend
and customize protection operation. Protection free-form SEL
OGIC control
equation programming includes a complete set of timers, counters, and
variables.
For all protection settings, including protection SEL
OGIC control equation
programming, there are six groups of settings that you activate with the
protection settings group selection. Only one group is active at a time. When
you switch groups, for example, you can activate completely different
programming that corresponds to the conditions indicated by the active group.
If you want the programming to operate identically in all groups, develop the
settings in one group and copy these to all groups. You can copy settings using
the COPY command. You can also perform cut-and-paste operations in the
ACSELERATOR QuickSet
®
SEL-5030 software.
NOTE: Perform operations that are
not time critical in automation
SEL
OGIC control equation
programming. You can use this
automation to reduce the demand and
complexity of protection SEL
OGIC
control equation programming.
All of the SELOGIC control equation programming in the protection area
executes at the same deterministic interval as the protection algorithms.
Because of this type of programming execution, you can use protection free-
form and fixed programming to extend and customize protection operation.
Remote Bits
Remote bits provide a means for sending remote control commands to relay
logic. As indicated in Description of Commands, remote bits have three
operating states: clear, set, and pulse. It is important to understand the
differences between the use of pulsed remote bits in automation and
protection SEL
OGIC control equations.
A pulsed remote bit will assert the respective remote Relay Word bit (RBnn,
nn = 01–32) for one processing interval (1/8 of a power system cycle). When
used in protection SEL
OGIC, which also executes at one processing interval,
pulsed remote bits provide a momentary means for operating a variety of logic
functions, including protection latches, Boolean logic expressions, and
protection logic counters. Because the pulsed remote bit and protection
processing both operate within the same processing interval, the use of pulsed
remote bits is reliable and deterministic.
Special conditioning is applied to remote bits within automation SEL
OGIC.
Because automation logic is not deterministic, and its processing interval
varies depending upon relay burden, remote bits that assert for less than the
time required to run an automation logic processing interval would not
normally be detected within the automation logic, making the use of rapidly
changing (assert/deassert in less than one automation logic processing
interval) remote bits and pulsed remote bits within automation logic
unreliable.
To provide reliable detection of pulsed remote bits that assert for one
protection logic processing interval within automation logic, conditioning is
applied to the remote bit to extend the momentary assertion through the
automation processing interval. This conditioning assures the reliable
detection of remote bit (RB01–RB32) assertion in automation logic.
SEL recommends that you assign a Protection Math Variable (PMVnn,
nn = 01–64) to each remote bit that may be asserted momentarily within the
automation logic processing interval to accurately reflect the state of the
remote bit in automation logic. Remote bits that assert and deassert multiple
times within the same automation logic processing interval will be processed
as asserting continuously for the entire automation logic processing interval.
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