3.31
Date Code 20170601
Instruction Manual
SEL-387-0, -5, -6 Relay
Differential, Restricted Earth Fault, Thermal, and Overcurrent Elements
Temperature Measurement (SEL-387-5 and SEL-387-6 Relays)
Temperature Measurement (SEL-387-5 and
SEL-387-6 Relays)
For temperature measurement purposes, the SEL-387 accepts RTD inputs
from the SEL-2600A RTD Module via any one of the serial ports. Set the RTD
enable and the RTD alarm and trip settings under group settings. Set the RTD
configuration under the port settings. A discussion of these settings follows.
Setting Descriptions
RTD Enable (E49A, E49B)
Range: Y, N
The relay can accept 12 RTD inputs from each of two SEL-2600A RTD
Modules (total of 24 RTD inputs). The two groups of RTD inputs are labeled
“49A” and “49B,” respectively.
RTD Alarm and Trip Settings (49A01A–49T12A and 49A01B–49T12B)
Range: OFF, 32–482°F; OFF, 0–250°C
Set the temperature value for alarm and trip operations.
The relay can accept 12 RTD inputs from each of two SEL-2600A RTD
Modules (total of 24 RTD inputs). Configure the SEL-387 and SEL-2600A
communication with the port setting SET P
n
(
n
= 1, 2, 3, or 4).
Temperature Preference (TMPREFA, TMPREFB)
Range: C, F
Located under the Global settings, TMPREFA, TMPREFB select the
preferred temperature units: C for Celsius or F for Fahrenheit. The relay
automatically recalculates all 49-element temperature values.
The SEL-387 can report a different RTD alarm or trip temperature than the
temperature you entered for settings 49A01A–49T12A and 49A01B–49T12B.
The relay rounds digits after the decimal point, processes the rounded values,
and reports temperature in unit-precision (e.g., 25, 72). The rounded result can
differ from the temperature setting especially when settings TMPREFA or
TMPREFB are F (Fahrenheit). The relay converts Fahrenheit scale settings to
the Celsius scale for processing, and then reconverts these temperatures to the
Fahrenheit scale for reporting. For example, if setting 49A01A is 101°F, the
relay reports 100°F.
Equation 3.13
38°C • 1.8 + 32° = 100.4°F = 100°F reported temperature, rounded to 100°F.
Setting 49A01A °F–32°
1.8
---------------------------------------------------------
101°F–32°
1.8
--------------------------
=
38.3°C internal relay processing
=
temperature, rounded to 38°C
Содержание SEL-387-0
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