Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

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2.7
Date Code 20171021 Instruction Manual SEL-421 Relay
Installation
Shared Configuration Attributes
The control input accuracy is ±5 percent of the applied signal plus ±3 Vdc. The
maximum voltage input is 300 Vdc, and the relay samples the control inputs at
2 kHz. See
Data Processing on page 9.1 in the SEL-400 Series Relays Instruction
Manual .
Optoisolated
The SEL-421 main board inputs, and the inputs on the optional I/O interface
boards (INT2, INT3, INT4, INT7, or INT8 I/O boards—see
Models and Options
on page 1.5 ), are fixed pickup threshold, optoisolated, control inputs. The pickup
voltage level is determined for each board at ordering time.
NOTE:
The SEL-421 main board and
the INT2, INT3, INT4, INT7, and INT8
I/O interface boards have optoisolated
contact inputs that can be used in
either polarity.
Use these inputs for monitoring change-of-state conditions of power system
equipment. These high-isolation control inputs are ground-isolated circuits and
are not polarity sensitive. In other words, the relay will detect input changes with
voltage applied at either polarity.
Inputs can be independent or common. Independent inputs have two separate
ground-isolated connections, with no internal connections among inputs. Com-
mon inputs share one input leg in common; all input legs of common inputs are
ground isolated. Each group of common inputs is isolated from all other groups.
Nominal current drawn by these inputs is 8 mA or less with 6 voltage options
covering a wide range of voltages, as listed in
Control Inputs on page 1.15 . You
can debounce the control input pickup delay and dropout delay separately for
each input, or you can use a single debounce setting that applies to all the contact
input pickup and dropout times (see
Global Settings on page 8.2 ).
AC Control Signals
Optoisolated control inputs can be used with ac control signals, within the ratings
shown in
Control Inputs on page 1.15 . Specific pickup and dropout time-delay
settings are required to achieve the specified ac thresholds, as shown in Table 2.2 .
NOTE:
Only the optoisolated control
inputs can be used to detect ac
control signals. Direct-coupled control
inputs can only be used with dc
control signals.
It is possible to mix ac and dc control signal detection on the same interface
board with optoisolated contact inputs, provided that the two signal types are not
present on the same set of combined inputs. Use standard debounce time settings
(usually the same value in both the pickup and dropout settings) for the inputs
being used with dc control voltages.
Table 2.2 Required Settings for Use with AC Control Signals
Global Settings
a
a
First set Global setting EICIS := Y to gain access to the individual input pickup and dropout timer
settings.
Prompt Entry
b
b
These are the only setting values that SEL recommends for detecting ac control signals. Other
values may result in inconsistent operation.
Relay Recognition Time for AC
Control Signal state change
IN nmm PU
c
c
Where
n
is 1 for Main Board, 2 for Interface Board 1, and 3 for Interface Board 2;
mm
is the number
of available contact inputs depending on the type of board.
Pickup Delay 0.1250 cycles 0.625 cycles maximum (assertion)
IN nmm DO
c
Dropout Delay 1.0000 cycle 1.1875 cycles maximum
(deassertion)