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4.87
Date Code 20081022
Instruction Manual
SEL-787 Relay
Protection and Logic Functions
Global Settings (SET G Command)
NOTE:
The AIx0yNAM setting cannot
accept the following and will issue the
Invalid Element message:
Analog Quantities
Duplicate Names
Other AI Names
Because the analog card is in Slot
3
, type
SET G AI301NAM <Enter>
to go
directly to the setting for Slot
3
, Input 1. Although the device accepts
alphanumeric characters, the name AI
x
0
y
NAM setting must begin with an
alpha character (A through Z) and not a number. The device displays the
following prompt:
AI301 TAG NAME (8 Characters) AI301NAM:= AI301 ?
Use the Instrument Tag Name to give the analog quantity a more descriptive
name. This tag name appears in reports (EVENT, METER, and SUMMARY)
instead of the default name of AI301. SEL
OGIC
control equations, Signal
Profiles, and Fast Message Read use the default names. Use up to eight valid
tag name characters to name the analog quantity. Valid tag names characters
are: 0–9, A–Z, and the underscore (_). For this example, we assign TX_TEMP
as the tag name.
Because this is a 4–20 mA transducer, enter
I <Enter>
(for current driven
device) at AI301TYP, the next prompt (enter
V
if this is a voltage-driven
device). The next two settings define the lower level (AI301L) and the upper
level (AI301H) of the transducer. In this example, the low level is 4 mA and
the high level is 20 mA.
AI301 TYPE (I,V) AI301TYP:= I ?
NOTE:
Because the SEL-787 accepts
current values ranging from –20.48 to
20.48 mA, be sure to enter the
correct range values.
The next three settings define the applicable engineering unit (AI301EU), the
lower level in engineering units (AI301EL) and the upper level in engineering
units (AI301EH). Engineering units refer to actual measured quantities, i.e.,
temperature, pressure, etc. Use the 16 available characters to assign
descriptive names for engineering units. Because we measure temperature in
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
. Set inputs connected to voltage driven
transducers in a similar way.
Содержание SEL-787
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