HF170AEN_OS_v0501_04
Page 17
5 - POWER MANAGEMENT
When used with the internal battery option, the user may hold the concern of reliable measurement
over a long period of time. The F170-A-OS has several smart power management functions to
extend the battery life time significantly. Two of these functions can be set:
LCD NEW
51
The calculation of the display-information influences the power
consumption significantly. When the application does not require a fast
display update, it is
strongly advised
to select a slow refresh-rate.
Please understand that NO information will be lost; the signal will be
processed and the output-signals will be generated in the normal way.
The following can be selected:
Fast - 1 sec - 3 sec - 15 sec - 30 sec - off.
Example 3:
Battery life-time
battery life-time with FAST update: about 1 years.
battery life-time with 1 sec update: about 3 years.
Note:
after a button has been pressed by the operator - the display
refresh-rate will always be FAST during 30 seconds. When "OFF" is
selected, the display will be switched-off after 30 seconds and will be
switched-on as soon as a button has been pressed.
BATTERY-MODE
52
The unit has two modes: operational or shelf.
After "shelf" has been selected, the unit can be stored for several years; it
will not process the signal, the display is switched-off but all settings and
totals are stored. In this mode, power consumption is extremely low.
To wake-up the unit again; press the SELECT-key twice.
6 - SENSOR
SIGNAL
61
The F170-A-OS can process the (0)4-20mA signal in two ways:
Interpolation: the signal is processed linear
L = S x I
Square root: for differential pressure
L = S
√
I
where:
L = Level: the calculated level
S = Span: the maximum flowrate at 20mA. The span is programmed
with setting 14.
I = Input: the scaled analog value; in these formulas value 0 (zero)
for (0)4mA and value 1 (one) for 20mA.
FILTER
62
The analog output signal of a sensor does mirror the actual level. This
signal is measured several times a second by the F170-A-OS. The value
measured is a "snap-shot" of the real level as it will be fluctuating. With
the help of this digital filter a stable and accurate reading can be obtained
while the filter level can be set to a desired value.
The filter principal is based on three input values: the filter level (01-99),
the last measured analog value and the last average value. The higher
the filter level, the longer the response time on a value change will be.
Below, several filter levels with there response times are indicated:
Continued next page >>>