User manual - METER SRT-147
8.
THE ALARM LED
Alarm LED (
AL
) lights in cases:
•
exceeding of
permissible measurement range
•
detection of sensor malfunction (shortcut or break of measurement circuit)
9.
ANALOGUE OUTPUT VALUE CALCULATION
Lets assume that we have active current output and its parameters are:
“modE”
=
“4-20”
,
“OUtL”
= 100,
“OUtH”
= 200,
“Lo r”
= 5.0,
“Hi r”
= 5.0
Parameters
“Lo r”
and
“Hi r”
define working range of current output to 3.8 ÷ 21 mA.
Output current will be calculated for three displayed values „D”:
a) D = „17.5”
According to formula from page 29:
I
out
= (17.5-10.0) / (20.0-10.0) × 16 mA + 4 mA = 0.75 ·16 + 4 = 16 mA
Calculated I
out
do not exceeds the output working range (3.8 - 21 mA).
b) D = „20.5”
According to formula from page 29:
I
out
= (20.5-10.0) / (20.0-10.0) × 16 mA + 4 mA = 1.05 ·16 + 4 = 20.08 mA
Calculated I
out
do not exceeds the output working range (3.8 - 21 mA).
c) D = „30.0”
According to formula from page 29:
I
out
= (30.0-10.0) / (20.0-10.0) × 16 mA + 4 mA = 2 ·16 + 4 = 36 mA.
Calculated I
out
exceeds the output working range (3 - 21 mA), so current output will generate
current equal to the upper border of range defined by parameter
“Lo r”
i
“Hi r”
(it means
21 mA).
36
