Badger Meter 106-255 - Manual

HOOK-UP INSTRUCTIONS – MODEL 106-255
SIGNAL CONDITIONER, MODULATED CARRIER, METER MOUNTED
APPLICATION
The Model 106-255 Meter Mounted Modulated Carrier
Signal Conditioner is intended for use with the wide
range Cox Series ANC and LFC Turbine Flowmeters.
The signal conditioner is designed to be mounted
directly to the flowmeter and when installed in this
way is contained in an explosion-proof housing. The
following describes the available options for
installation and connection to peripheral
instrumentation.
INSTALLATION
Figures 1A and 1B illustrate the most commonly used
methods for electrically interfacing to the signal
conditioner. Figure 1A is referred to as the TWO
WIRE INTERFACE while Figure 1B illustrates the
typical THREE WIRE INTERFACE. In both
instances, a regulated DC power source is required
as is some type of frequency meter or programmed
rate indicator, used to process or display the
flowmeter signal. The regulated DC power source
should provide an output of between 15 and 28 volts
DC with a minimum output current capability of 100
milli-amperes. Also, in either configuration the
flowmeter pick-off is connected directly to the
terminals labeled “A” and “B”.
TWO WIRE INTERFACE
In general, the advantage to the Two Wire Interface is
the inherent higher noise immunity, especially when
connected over long distances. It also offers a
simpler interconnect with fewer wires. In the Two
Wire Interface the signal conditioner is connected to
the regulated power supply through a series dropping
resistor. The pulsing action of the signal conditioner
causes a modulating current flow through the series
resistor, producing a near symmetrical square wave
signal output.
Figure 2 illustrates the typical output signal produced
by the two wire interface. Note that the minimum
excursion of the output signal does not return to a
zero volt or ground reference. This characteristic of
the two wire interface may cause some difficulty in
selection of the frequency counter or rate indicator. A
typical “TTL” compatible interface requires that the
minimum signal excursion be near zero volts. Some
indicators may require the signal to pass through
zero, going negative. A level shifting device or DC
blocking capacitor may be required to remove the
unwanted DC component. If these are not possible
alternatives, the Three Wire Interface should be
considered.
Bulletin 106-255
Figure 1A. Typical hook-up for a Two Wire Interface. Connect
flowmeter pick-off terminals “A” and “B”. Jumper terminals “O” and
“C” as indicated. Select R
series
and supply voltage according to
instructions.
Figure 1B. Typical Three Wire Interface. Connect flowmeter pick-
off at terminals “A” and “B” as shown. No connection to terminal
“O”. Pull-up resistor R
p
selected according to instructions.