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13.9
Date Code 20171006
Instruction Manual
SEL-400 Series Relays
SEL
OGIC
Control Equation Programming
SEL
OGIC
Control Equation Elements
SEL
OGIC
Control Equation Elements
SEL
OGIC
control equation elements are a collection of storage locations, timers,
and counters that you can use to customize the operation of your relay and to
automate substation operation. The elements that you can use in SEL
OGIC
control
equations are summarized in
. The specific number of the various types
of elements varies between SEL-400 series relays. See the product-specific
instruction manual to determine the number of each type of element in that relay.
Relay Word Bits and Analog Quantities
Data within the relay are available for use in SEL
OGIC
control equations. Relay
Word bits are binary data that include protection elements, input status, and out-
put status. See
Section 11: Relay Word Bits
in each product-specific instruction
manual to view a list of Relay Word bits available within that relay. Analog quan-
tities are analog values within the relay including measured and calculated val-
ues.
Section 12: Analog Quantities
in each product-specific instruction manual
contains a list of analog quantities available within the relay.
Special Condition Bits
Several Relay Word bits are available for special conditions related to SEL
OGIC
control equation programming in the relay. You can use these bits in SEL
OGIC
control equation programming to react to these conditions. You can also send
these bits to other devices through relay interfaces including M
IRRORED
B
ITS
communications and DNP3. The special condition bits are shown in
The relay sets the first execution bits AFRTEXA, AFRTEXP, and PFRTEX
momentarily to allow you to detect changes in the relay operation. The relay sets
these bits and clears them as described in
, and
You can use these bits to force logic and calculations to reset or take a known
state on power-up or settings change operations.
Table 13.1
Summary of SEL
OGIC
Control Equation Elements
Element
Description
Relay Word bits
Boolean value data
Analog quantities
Received, measured, and calculated values
Special condition bits
Bits that indicate special SEL
OGIC
control equation execution
conditions
SEL
OGIC
control equation
variables
Storage locations for the results of Boolean SEL
OGIC
control
equations
SEL
OGIC
control equation
math variables
Storage locations for the results of math SEL
OGIC
control equations
Latch bits
Nonvolatile storage for the results of Boolean SEL
OGIC
control
equations
Conditioning timers
Pickup and dropout style timers similar to those used in SEL-300
series relays
Sequencing timers
On-delay timers similar to those used in programmable logic con-
trollers
Counters
Counters that count rising edges of Boolean value inputs
Summary of Contents for SEL-421-4
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