Nivus osm-f, Инструкция по эксплуатации

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Instruction Manual
OCM F
OCM F - Rev. 04 as of 18.02.2014 Page 91
12 Verification of the Measurement System
12.1 General
The verification of the measurement system should be carried out by the NIVUS
service if possible or by an expert company authorised by NIVUS.
In case of an initial general verification carried out by hydraulically and technical-
ly well-versed personnel, proceed according to the guidelines described below:
− Check power supply on the OCM F. The according slide switch on the board
must be engaged (see Fig. 7-12). The main screen must be visible on the
transmitter display.
− Check the communication between flow velocity sensor or combi sensor and
transmitter at I/O/Doppler-Info
− If the sensor(s) is/are not recognised, check the connections as well as over-
voltage protection elements which might have been used
− Check the level measurement
− Check the flow velocity measurement
− Check analog and digital inputs and outputs (see Chap. 9.5.1, 9.5.2 as well
as Chap. 12.2 and 12.3)
For initial assessment mainly the I/O menu as well as the >I-key< on the trans-
mitter are helpful.
Refer to chapter 11 to locate the most prominent errors.
12.2 Verification of Combi Sensor with Pressure Measurement Cell
Due to physical reasons, the level measurement using sensors with pressure
measurement cell is subject to long-term drift (see >Technical Instructions of
Doppler Sensors<). NIVUS therefore recommend to calibrate sensors with inte-
grated pressure measurement cells twice per year regarding the zero point. The
best calibration results can be achieved if the water level is as low as possible or
by dismantling and removing the sensors from the measurement medium.
The calibration procedure is described in Chapter 9.6.1.
Adjusting the zero point by measuring the current filling level with a yardstick,
a ruler or similar in the flowing medium is tending to errors. As soon as the
ruler (or yardstick) is being put into the flowing water the resulting surge will
lead to measurement errors depending on the current flow velocity. This is
why the filling level for reference measurement purposes has to be measured
always
from top down!