GE L90 Instruction Manual page 413

5 SETTINGS
Hardware and software is provided to generate dcmA signals that allow interfacing with external equipment. Specific hard-
ware details are contained in chapter 3. The dcmA output channels are arranged in a manner similar to transducer input or
CT and VT channels. The user configures individual channels with the settings shown below.
The channels are arranged in sub-modules of two channels, numbered 1 through 8 from top to bottom. On power-up, the
relay automatically generates configuration settings for every channel, based on the order code, in the same manner used
for CTs and VTs. Each channel is assigned a slot letter followed by the row number, 1 through 8 inclusive, which is used as
the channel number.
Both the output range and a signal driving a given output are user-programmable via the following settings menu (an exam-
ple for channel M5 is shown).
The relay checks the driving signal (x in equations below) for the minimum and maximum limits, and subsequently re-
scales so the limits defined as
ing equation is applied:
where: x is a driving signal specified by the
I and I are defined by the
min max
k is a scaling constant calculated as:
The feature is intentionally inhibited if the
< 0.1 pu. The resulting characteristic is illustrated in the following figure.
VAL
The dcmA output settings are described below.
• DCMA OUTPUT H1 SOURCE: This setting specifies an internal analog value to drive the analog output. Actual values
(FlexAnalog parameters) such as power, current amplitude, voltage amplitude, power factor, etc. can be configured as
sources driving dcmA outputs. Refer to Appendix A for a complete list of FlexAnalog parameters.
• DCMA OUTPUT H1 RANGE: This setting allows selection of the output range. Each dcmA channel may be set inde-
pendently to work with different ranges. The three most commonly used output ranges are available.
• DCMA OUTPUT H1 MIN VAL: This setting allows setting the minimum limit for the signal that drives the output. This
setting is used to control the mapping between an internal analog value and the output current (see the following
examples). The setting is entered in per-unit values. The base units are defined in the same manner as the FlexEle-
ment™ base units.
• DCMA OUTPUT H1 MAX VAL: This setting allows setting the maximum limit for the signal that drives the output. This
setting is used to control the mapping between an internal analog value and the output current (see the following
GE Multilin
and match the output range of the hardware defined as
MIN VAL MAX VAL
<
⎧ I if x
MIN VAL
min
⎪
>
⎨ I if x
I
= MAX VAL
max
out
⎪
( )
⎩ k x
– +
MIN VAL
setting
SOURCE
setting
RANGE
I –
max
k
= ------------------------------------------------ -
–
MAX VAL
and
MAX VAL MIN VAL
I
max
I
min
DRIVING SIGNAL
MIN VAL
Figure 5–145: DCMA OUTPUT CHARACTERISTIC
L90 Line Current Differential System
5.9 TRANSDUCER INPUTS AND OUTPUTS
I otherwise
min
I
min
MIN VAL
settings are entered incorrectly, e.g. when
MAX VAL
842739A1.CDR
. The follow-
RANGE
(EQ 5.27)
(EQ 5.28)
–
MAX VAL MIN 5
5-277