Sel 751A - Analog (DC Transducer) Input Board; Figure 4.56 Settings to Configure Input 1 as a 4-20 Ma Transducer

4.102
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Analog Inputs
this example, enter “degrees C” (without quotation marks) as engineering
units. Enter –50 <Enter> for the lower level and 150 <Enter> for the upper
level.
With the levels defined, the next six settings provide two warning settings and
one alarm setting for low temperature values, as well as two warning settings
and one alarm setting for high temperature values. State the values in
engineering units, not the setting range of the transducer. Note the difference
between low warnings and alarm functions and high warnings and alarm
functions: low warnings and alarm functions assert when the measured value
falls below the setting; high warnings and alarm functions assert when the
measured values rise above the setting.
In this example, we measure the oil temperature of a power transformer, and
we want the following three actions to take place at three different temperature
values:
➤ At 65°C, start the cooling fans
➤ At 95°C, send an alarm
➤ At 105°C, trip the transformer
Because we are only interested in cases when the temperature values exceed
their respective temperature settings (high warnings and alarm functions), we
do not use the low warnings and alarm functions. Therefore, set the lower
values (AI301LW1, AI301LW2, AI301LAL) to OFF, and the three higher
values as shown in Figure 4.56. Set inputs connected to voltage driven
transducers in a similar way.
=>>SET G AI301NAM TERSE <Enter>
Global
AI 301 Settings
AI301 TAG NAME (8 characters)
AI301NAM:= AI301
? TX_TEMP <Enter>
AI301 TYPE (I,V) AI301TYP:= I ? <Enter>
AI301 LOW IN VAL (-20.480 to 20.480 mA) AI301L := 4.000 ? <Enter>
AI301 HI IN VAL (-20.480 to 20.480 mA) AI301H := 20.000 ? <Enter>
AI301 ENG UNITS (16 characters)
AI301EU := mA
? degrees C <Enter>
AI301 EU LOW (-99999.000 to 99999.000) AI301EL := 4.000 ? -50 <Enter>
AI301 EU HI (-99999.000 to 99999.000) AI301EH := 20.000 ? 150 <Enter>
AI301 LO WARN L1 (OFF,-99999.000 to 99999.000) AI301LW1:= OFF ? <Enter>
AI301 LO WARN L2 (OFF,-99999.000 to 99999.000) AI301LW2:= OFF ? <Enter>
AI301 LO ALARM (OFF,-99999.000 to 99999.000) AI301LAL:= OFF ? <Enter>
AI301 HI WARN L1 (OFF,-99999.000 to 99999.000) AI301HW1:= OFF ? 65 <Enter>
AI301 HI WARN L2 (OFF,-99999.000 to 99999.000) AI301HW2:= OFF ? 95 <Enter>
AI301 HI ALARM (OFF,-99999.000 to 99999.000) AI301HAL:= OFF ? 115 <Enter>
AI 302 Settings
AI302 TAG NAME (8 characters)
AI302NAM:= AI302
? END <Enter>
Save changes (Y,N)? Y <Enter>
Settings Saved
=>>
Figure 4.56 Settings to Configure Input 1 as a 4–20 mA Transducer
Measuring Temperatures Between —50°C and 150°C
Analog (DC
Transducer) Input
Board
Table 4.47 shows the setting prompt, setting range, and factory default settings
for an analog input card in Slot 3. For the name setting (AI301NAM, for
example), enter only alphanumeric and underscore characters. Characters are
not case sensitive, but the device converts all lowercase characters to
uppercase. Although the device accepts alphanumeric characters, the name
AI301NAM setting must begin with an alpha character (A–Z) and not a
number.