SOR RF Continuous Level Transmitter User Manual
Page 6
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Form 837 (05.13) ©SOR Inc.
Blind Calibration
Electrical power must be disconnected from explosion proof models before
the cover is removed. Failure to do so could result in severe personal injury
or substantial property damage.
Use this calibration method when it is not possible
to raise or lower the level of the process in the
vessel or tank. Do not permanently install the unit
until after setting the ZERO (4 mA) point.
Use the wiring configuration in
when the
loop cannot be conveniently opened for current
monitoring. Attach a current meter as shown.
Turn both potentiometers (fine adjustments
for ZERO and SPAN) fully counterclockwise.
(See
)
Current Meter
- +
TB1
Loop Power
Terminal Block
Control
Board
M-
M+
M- and M+ optional
wiring diagram
Zero Adjustment (4 mA)
Close switch #1 on coarse adjustment switches for ZERO and SPAN. (See
)
Open switches #2, #3, and #4 on both coarse adjustment switches per
.
With the end of the probe just touching the process, view the output. If the output is
less than 4 mA, turn the fine ZERO adjustment clockwise until 4 mA is reached.
NOTE: Only one ZERO switch may be in the closed position at any time.
If the output is more than 4 mA, (opening the previous switch) close each coarse
adjustment switch individually until a reading less than 4 mA is attained. Turn the fine
ZERO adjustment clock-wise until 4 mA is reached.
NOTE: If 4 mA cannot be obtained, see the troubleshooting chart on page 14.
Span Adjustment (20 mA)
Calibrate for span by determining the present level in the tank, and setting the span
proportionally. For best results, the level should be at 50% or greater.
Determine the level present in the tank. Complete the unit installation, except for the
housing cover.
Calculate the expected current output using the following formula: 20mA x (% of tank
fill) 20mA = output.
For example: Tank level is at 50%, set SPAN coarse and fine for 20mA reading (16mA x
50% + 4mA, If the material level is at 90%, set the span adjustment for 18.4 mA (16mA
x 90% + 4mA, The 100% fill level should be verified at the earliest opportunity.
If the zero setting is changed, the span will change, and the unit must be recalibrated.