Meter Head; Block Diagram - RMG TERZ 94 Operating Instructions Manual

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The TERZ 94 / 94-S volumeters form a series of uniform construction.
The meters consist of the following principal components:
- meter case
- measuring element (with turbine wheel and sensor) and
- electronic totalizing unit.
An aerodynamic flow straightener (8) fitted into the meter case constricts the effective cross
section of the pipe to form a ring-shaped cross-sectional area and substantially eliminates
turbulences. The velocity of the flowing gas increases and the gas is directed to the turbine blades.
The turbine wheel (7) is dynamically balanced and mounted with dust-proof ball bearings (6). A
permanent magnet (4) located at the end plate of the turbine shaft induces the sensor element (3)
to give a voltage pulse with each rotation of the turbine wheel. This pulse is further processed by
the electronic system of the meter head (1).

Meter head

Inside the meter head, the number of pulses is divided by the meter factor (number of pulses per
m3) and the result is used to calculate the volume at measurement conditions. In the main totalizer,
the sum of the volume at measurement conditions which flowed through the meter is formed and
you can read the gas volume which flowed through the meter per time unit on the flow rate display.
At the HF output, the unchanged signal frequency of the sensor element is outputted, whereas, for
the LF output, this HF frequency can be reduced by two programmable scaling factors.

Block diagram

TERZ 94
In the display field of the TERZ 94 (not with the TERZ 94-S), a start-stop totalizer or a resettable
totalizer can be optionally displayed. Through the free sensor input X5, either the volume metering
of the start-stop totalizer is interrupted or the resettable totalizer is reset (depending on the
programming of the TERZ 94).
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Manual TERZ 94 · EN09a · 2017-11
FUNCTIONAL DESCRIPTION
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