24
Programming Functions
3-MEASURE (continued)
Cut-off=%
is the low flow zero threshold. When the flow
rate falls below this parameter, the flow rate is assumed
to be
0
and set to such a value by the converter. This
parameter can be set from
0
to
25.0%
of the full scale
value. This function is the compliment to
Peak thr
as it
sets the lower limit of measurable flow rate.
Autocal.=
is the auto-calibration function. When enabled
the converter performs a calibration cycle once every
hour. During such a cycle, the flow rate is “frozen” at the
last measured value. The calibration lasts from 8 to 15
seconds and allows removal of temperature induced
errors. This function is recommended to be enabled if
the instrument undergoes large temperature variations
while operating. This can be set to
ON
or
OFF
.
Autorange=
is a function used to automatically change
from the
Fs1
to
Fs2
range. The meter may have two
different working ranges in order to address variable
process conditions. In order to get the best results out
of this function, it is important to set the range of
Fs2
greater than range setting of
Fs1
.
When the flow rate increases and reaches the 100% of
Fs1
, the converter automatically switches to
Fs2
. When
the flow rate decreases, reaching a value on
Fs2
equal
to 90% of
Fs1
, then the active scale is changes back to
Fs1
. This may be set to
ON
or
OFF
.
NOTE:
The autorange feature disables the manual
change of the range from an external source (
Range
change, 5-INPUTS
menu).
E.saving=
is the Energy saving function. This function
is particularly useful when the instrument is powered by
a battery or solar cells, providing a 60-80% energy saving,
or when many flow sensors are in use. The energy
consumption is controlled by the ratio between the
measuring cycles powering the coils and the cycles
without powering the coils.
When the flow rate is stable the number of “off” cycles is
higher than the “on” cycles (lower frequency), so the
average consumption is greatly reduced. If the flow rate
suddenly changes, the meter switches to a higher
sampling frequency in order to respond faster to
fluctuations in flow rate. It returns to a lower sampling
frequency as soon as the flow rate stabilizes.
If the flow rate falls below the acceleration threshold (
Skip
thr
) percentage value, the meter goes on with “off” cycles.
As soon as the flow rate value exceeds this threshold,
the meter switches back to a higher sampling frequency.
The speed at which the meter switches on and off the
excitation cycles is different: changing from a constant
flow rate to a variable one the converter responds very
quickly. Switching from a variable rate to stable one the
converter responds much slower. This field may be set
to
ON
or
OFF
.
NOTE:
To optimize this function it is recommended that
a value of
5
to
10
be set for the acceleration threshold
(
Skip thr
).
Effect of Peak threshold
Summary of Contents for LIQUID CONTROLS HML210
Page 43: ...43 Notes...
