Contrec 515 FA01, Руководство по эксплуатации

Страница: 12 / 98

Introduction
2 515 FA01 - 29 August 2021
Calculation Modes
This instrument is capable of operating in the following modes:
• Addition (Channel 1 + Channel 2)
• Subtraction (Channel 1 - Channel 2)
When subtraction mode is selected the larger flow should be connected to
channel 1. The instrument can also be programmed to perform the
calculation on either the frequency inputs (FINP1 and FINP2) or the analog
inputs (AINP3 and AINP4).
The operation mode can be observed via Modbus RTU communications.
Please refer to
Instrument Control and I/O on page 69 for further details.
Calculations
The following equations identify the derivation of some of the displayed
variables. If your interest is more in the operation of the instrument, you can
skip this section and allow the instrument to take care of the calculations.
For frequency inputs the calculation of totals are exact as the instrument
collects all pulses detected on each channel.
channel total = pulses / k-factor
The flow rates are derived from an accurately measured frequency:
channel flow = frequency / k-factor
For analog inputs, to derive the flow rate, the analog input is normalised to
a value (A) between 0 and 1.
channel flow = (V
f
max - V
f
min)A + V
f
min
The resultant values are then:
ADD result = channel 1 + channel 2
SUB result = channel 1 - channel 2
channeltotal channelflow

t
  

=