PD8-6262 Explosion-Proof Dual Analog Input Flow Rate/Totalizer
Instruction Manual
55
Select Menu (
SElect
)
The
Select
menu is used to select the input signal conditioner applied to the inputs (linear, square root, or
programmable exponent), math function for A & B, constants, low-flow cutoff, total count direction (up or down from a
preset amount), and analog output programming. Multi-point linearization is part of the linear function selection.
Input Signal Conditioning (
Functn
)
The
Function
menu is used to select the input signal
conditioner applied to the input signal: linear, square
root, or programmable exponent. Multi-point
linearization is part of the linear function selection.
Each input channel input signal conditioner is
programmed independently.
Totalizers are set up at the factory for linear function
with 2-point linearization. The linear function provides
a display that is linear with respect to the input signal.
Square Root Linearization
(
Square
)
The square root function is used to calculate flow
measured with a differential pressure transmitter. The
flow rate is proportional to the square root of the
differential pressure. Scale the totalizer so that the
low input signal (e.g. 4 mA) is equal to zero flow and
the high input signal (e.g. 20 mA) is equal to the
maximum flow.
Programmable Exponent
Linearization (
Prog E
)
The programmable exponent function is used to
calculate open-channel flow measured with a level
transmitter in weirs and flumes. The flow rate is
proportional to the head height. Scale the totalizer so
that the low input signal (e.g. 4 mA) is equal to zero
flow and the high input signal (e.g. 20 mA) is equal to
the maximum flow. This method works well for all
weirs and flumes that have a simple exponent in the
flow calculation formula. For weirs and flumes with
complex exponents it is necessary to use a strapping
table and the 32-point linearization of the totalizer.
