14
Figure 6: Flange plug of the preamplifier housing
19. Preamplifier Technical Data
Fig. 6 depicts the pin assignment of the preamplifier. This plug has five pins.
Two pins are for the power supply (pin 1 and 3), two for the signal output
of channel 1, 2 (pins 2 and 4) and a separate output for error or direction
detection (pin 5).
However, please note that the cable shield at the plug side is on the metal
housing of the plug. The connection cable shield must be applied on both
sides. The shield is used to connect the PE from the evaluation electronics to
the preamplifier housing and the measuring element of the flow meter. The
cable shield should always be continuous to the flow meter and not sepa-
rated by distribution boxes or junction boxes. Route the connection cable
as directly as possible from the evaluating device to the flow meter since
interruptions are always potential sources of error. The measuring elements
of the flow meter must be connected electrically with the protective earth
conductor (PE). This is generally ensured with the grounded pipelines.
If potential differences exist between the preamplifier housing and
the protective conductor (PE) of the evaluating device, you must pro-
vide equalization.
Important:
Use only well shielded connection cables with a wire cross-section of ≥ 4 to 5 x 0.25 mm². Please note
that the housing of the round pin plug is metallic, has a connection for the
shield and that the potential of the PE is connected to the cable shield and the housing
of the preamplifier.
Important:
Please make sure that no additional inductors such as contactors, relays, valves, etc. are
connected to the power supply of the flow meter. These components are potential sources
of interference (especially if the inductors are not provided with adequate protective circuits), produce
high interference pulses during the switching, and may disrupt the function
of the flow meter even though it complies with the EMC directives.
Pin 2
Digital signal
Channel 1
Pin 1
Power supply
V
b
= 10-28 VDC
Pin 4
Digital signal
Channel 2
Metal housing connected with
shield and protective earthing
conductor PE
Pin 5
Digital signal
ERROR/DIREC
Pin 3
Power supply
GND (-V
b
= 0 V)
Plug top view
Depending on the operating conditions, the service life and thus the specific characteristics
of the equipment are limited due to wear, corrosion, deposits, or aging. The operator is responsible for
carrying out periodic inspections, maintenance, and re-calibrations. Each observation of a malfunction
or damage makes it necessary to stop operation. We can loan a device for the duration of the overhaul
if requested. We recommend an annual inspection and recalibration.
20. Maintenance
