Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

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Date Code 20171006 Instruction Manual SEL-400 Series Relays
DNP3 Communication
DNP3 Documentation
You can customize the DNP3 analog input map with per-point scaling and dead-
band settings. Class scaling (DECPLA
n , DECPLV n , and DECPLM n ) and dead-
band settings (ANADBA n , ANADBV n , and ANADBM n ) are applied to indices
that do not have per-point entries. Per-point scaling overrides any class scaling
and dead-band settings. Unlike per-point scaling, class-level scaling is specified
by an integer in the range 0–3 (inclusive), which indicates the number of decimal
place shifts. In other words, you should select 0 to multiply by 1, 1 for 10, 2 for
100, or 3 for 1000.
NOTE:
The settings above contain
the DNP3 LAN/WAN session suffix n.
This suffix is not present in serial port
DNP3 settings.
Scaling factors allow you to overcome the limitations imposed, by default, of the
integer nature of Objects 30 and 32. For example, DNP3, by default, truncates a
value of 11.4 A to 11 A. You may use scaling to include decimal point values by
multiplying by a power of 10. For example, if you use 10 as a scaling factor,
11.4 A will be transmitted as 114. You must divide the value by 10 in the master
to see the original value including one decimal place.
You can also use scaling to avoid overflowing the 16-bit maximum integer value
of 32767. For example, if you have a value that can reach 157834, you cannot
send it using DNP3 16-bit analog object variations. You could use a scaling factor
of 0.1 so that the maximum value reported is 15783. You can then multiply the
value by 10 in the master to see a value of 157830. You will lose some precision
as the last digit is dropped in the scaling process, but you can transmit the scaled
value using the default variations for DNP3 Objects 30 and 32.
If your DNP3 master has the capability to request floating-point analog input
variations, the relay will support them. These floating point variations, 5 and 6
for Object 30 and 5–8 for Object 32, allow the transmission of 16- or 32-bit float-
ing point values to DNP3 masters. When used, these variations eliminate the
need for scaling and maintain the resolution of the relay analog values. Note that
this support is greater than DNP3 Level 4 functionality, so you must confirm that
your DNP3 master can work with these variations before you consider using
floating point analog variations.
The following example describes how to create a custom DNP3 map by point
type. The example demonstrates the
SET D command for analog inputs. Alter-
nately, you can use the QuickSet software to simplify custom data map creation.
The example uses quantities available in the SEL-411L, but similar operations
can be performed on any SEL-400 series relay.
Consider a case where you want to set the analog input points in a map as shown
in
Table 16.10 .
To set these points as part of custom map 1, you can use the SET D 1 TERSE
command as shown in Figure 16.5 .
Table 16.10 Sample Custom DNP3 Analog Input Map
Point Index Description Label Scaling Dead band
0 Fundamental IA magnitude LIAFM Default Default
1 Fundamental IB magnitude LIBFM Default Default
2 Fundamental IC magnitude LICFM Default Default
3 Fundamental IC magnitude LIAFM Default Default
4 Fundamental three-phase power 3P_F 5 Default
5 Fundamental A-Phase magnitude VAFM Default Default
6 Fundamental A-Phase angle VAFA 1 15
7 Frequency FREQ 0.01 1