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A.4 Setting Range Values (Local Zero and Span), Continued
Procedure, continued
Table A-3 Setting Range Values Using Local Zero and Span
Adjustments, Continued
Step Action
4
Turn ON transmitter power and let it warm up for a few minutes.
Using an accurate pressure source, apply desired zero equivalent
pressure to transmitter.
ATTENTION
For differential pressure transmitters, apply pressure
to the high pressure head for positive range values or vent both
heads to atmosphere for zero. If zero is to equal a negative value,
apply the equivalent pressure to the low pressure head. For
example, if zero is to equal –10 inH
2
O, you would apply 10 inH
2
O to
the low pressure head and vent the high pressure head for the zero
adjustment.
5
Check that milliammeter reading is 4 mA.
If reading … Then…
is less or greater than 4 mA go to Step 6.
is correct go to Step 7.
ATTENTION
If you have the smart meter with local zero and
span adjustment option, you may substitute the smart meter
readings for the milliammeter readings. For example, with zero input
pressure applied assume that the meter reads 4 inH2O instead of 0
inH2O. In this case, the meter reading is greater than 0 (or 4 mA).
6
a. Press and hold ZERO button on local zero and span assembly or
smart meter.
ATTENTION
The smart meter readings revert to the default unit of
percent (%) during this operation. If the error code Er0 appears on
the display, you are working with a model STD110 transmitter that
does not support the local zero and span adjustments.
b. Press Decrease button once to complete this function.
ATTENTION
The smart meter display goes blank for a 1/2
second and then returns reading 0%.
c. Check that milliammeter reading equals 4 mA and release ZERO
button.
ATTENTION
If milliammeter reading doesn’t change, be sure you
are not working with a model STD110 transmitter that ignores local
adjustments. The smart meter readings return to the set engineering
units after you release the ZERO button.
Continued on next page
56 ST 3000 Release 300 Installation Guide 2/05