Flow; Flow Calculation; Totalizing Flow; External Totalizers And Flow Samplers - Siemens SITRANS LUT400 Operating Instructions Manual

General Operation

7.9 Flow

7.9 Flow
7.9.1

Flow calculation

The SITRANS LUT400 provides numerous open channel flow calculation features (see Flow
(2.15.) (Page 229)).
The device can be configured to select the flow calculation specific to the primary measuring
device (PMD), such as a flume or weir. If the PMD does not match any of the eleven preset
PMD calculations, a universal flow calculation can be used (PMD = Universal Head Flow).
See Flow Calculation (Page 302) for more details.
The SITRANS LUT400 converts the head measurement into flow rate. The flow rate is
totalized and stored in a comprehensive data log to facilitate detailed flow analysis.
7.9.2

Totalizing flow

Totalizing of the calculated flow is ongoing. Daily and running totalizers can be viewed in
Totalizers (2.16.) (Page 237). The daily totalizer resets automatically every 24 hours at
23:59:59, and both can be reset by the user.
In order to adjust the rate of filling of the totalizer, the Totalizer Multiplier (2.7.3.3.)
(Page 195) can be set to an appropriate value. Totalizing that is specific to a time and date
can be viewed under View Logs for flow (see OCM (3.2.6.2.) (Page 243)).
Note
If power is lost to the LUT400, totalizer values may also be lost. Totalizer values are only
written to non-volatile memory once every hour.
The SITRANS LUT400 can be programmed to operate a remote totalizer by assigning any of
the relays to act as a totalizer contact. Under this function, the maximum rate of contact
closure is 5/s with a closure duration of 100 ms.
Typically the totalizer should be set for 300 to 3000 counts per day at maximum flow.
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7.10

External Totalizers and Flow Samplers

External totalizers are simple counters which count the number of relay clicks produced by
the SITRANS LUT400. This is generally used to keep track of OCM or pumped volume
totals. Note that both of these values are also stored in the SITRANS LUT400 and are
available through communications.
Flow samplers are devices which take a sample of liquid when triggered by a relay click.
These samples are used to monitor water quality over time. Flow samplers can be driven by
OCM volume, pumped volume, or by time depending on the application requirements.
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Operating Instructions, 07/2019, A5E33329501-AC
SITRANS LUT400