Flomec Oval Gear, Руководство по эксплуатации

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Many secondary flow instruments are fitted with an integral pull-up resistor, but if
connecting the Hall Effect output to an electronic device that does not contain an integral
pull-up resistor, one MUST be fitted by the installer. The pull-up resistor is connected
between the signal terminal and the +VDC terminal; the recommended pull-up resistor
value is 10k Ω , 2.4k Ω is the minimum value in a 24V (dc) system.
In low voltage systems using low pull-up resistor values, cases may occur where the
voltage level at the terminal will not be low enough to trigger the low-level logic on
receiving instruments. The equation below approximates the minimum pull-up resistor
value required based on the pull-up voltage level, and the low logic voltage threshold of the
instrument.
𝑅𝑅
𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝−𝑝𝑝𝑝𝑝
=
112 ∗ 𝑉𝑉
𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝−𝑝𝑝𝑝𝑝
𝑉𝑉
𝑝𝑝𝑙𝑙𝑙𝑙
− 0.05
− 102
𝑅𝑅
𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝−𝑝𝑝𝑝𝑝
= Minimum value of pull-up resistor
𝑉𝑉
𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝−𝑝𝑝𝑝𝑝
= Voltage that signal is being pulled up to
𝑉𝑉
𝑝𝑝𝑙𝑙𝑙𝑙
= Low logic voltage threshold
Note:
The hall effect sensor circuitry incorporates 2 x 51 ohm resistors in series with the
signal output.
2.2.3
Reed Switch Outputs
The reed switch output is a two wire normally-open SPST voltage free contact ideal for
installations without power, or for use as a simple apparatus in hazardous area locations.
When using the reed switch output the liquid temperature must not change at a rate
greater than 18°F (10°C) per minute, or the switch will be damaged. Reed switch reliability
and lifetime are very dependent on the voltage and current used; reducing system voltage
and switching current to a minimal value is recommended. Under ordinary conditions the
service life of the reed switch will exceed 2 billion actuations when switching less than 5V
(dc) and 10mA
(as is the case when used with any of the available Integral Instruments)