Model 10D1475H; Primary Signals; Systems With Integrated M2 Signal Converters; Table 4-1. Terminal Function Vs. Jumper Settings - ABB MINI-MAG 10D1475 Instruction Manual

10D1475 MINI-MAG MAGNETIC FLOWMETER INSTRUCTION BULLETIN

4.2 Model 10D1475H

4.2.1 Primary Signals

Model 10D1475H flowmeter uses Model M2 Converter electronics and may be either integral or
remote configuration. Primaries contain two flux producing coils wired in series and a pair of
diametrically opposed electrodes mounted at 90 degrees to the coil flux plane. Meter coils are
excited with approximately +10 volts of pulsed DC. A precision current sensing network is mounted
in series with the coils. The current sense network produces what Bailey-Fischer & Porter refers to
as a "Reference Voltage", which is typically +70 millivolts. The reference voltage is directly propor-
tional to the strength of the magnetic field in the measuring tube and is measured by the Signal
Converter. Reference voltage must be measured, since any variation in reference voltage will also
produce a proportional change in electrode signal voltage, assuming an unchanged flow velocity.
Flowmeters of the pulsed DC type operate on the principle that unwanted electrode signals occur
while the magnetic flux is changing. Accordingly, the signal converters have been designed to
capture the electrode voltage only during that portion of the excitation cycle when the magnetic flux
is constant. This interval occurs during the last 25% of each half excitation cycle.
operation of a magmeter system eliminates those variables capable of causing drift of the meter zero
point.
4.2.1.1 Systems With Integral M2 Signal Converters
When the flowmeter system is fitted with an integrally mounted M2 microprocessor Converter, then a
686B776 PCB assembly is installed underneath the converter module. This assembly incorporates
the following functional blocks:
• A precision Kelvin current sensing network in series with the coils
• An encapsulated AC coupled buffer preamplifier for each measuring electrode
• An EEPROM for retention of Primary span and zero correction factors
• Input/output lines for 4-20 mA current, scaled pulse or data link, contact
inputs/outputs (by jumper configuration; see table)
The resistive divider network which produces a converter reference voltage consists of a 0.9 ohm
Kelvin resistor and a precision a resistive divider network. The converter is designed to maintain the
reference voltage at +70 mV, and this in turn causes approximately 200 or 400 mA (as set by
jumpering) constant current to be delivered to the meter coils. The EEPROM is then programmed
with the mathematical corrections necessary to obtain an exact "constant meter capacity per size".
For the M2 integrally mounted converters, certain options are established by the position of jumpers
located on the lower left corner of the Primary Board. The jumper settings determine which combina-
tions of functions appear on configurable input/output terminals 39 & 40 (emitter & collector respec-
tively for opto-coupled output configurations). The specific function desired on these terminals must
be selected using the software menus in the Signal Converter. The following table and diagram
correlate the functions with the jumper positions:

TABLE 4-1. TERMINAL FUNCTION vs. JUMPER SETTINGS

Optional Combinations
Zero return / External Totalizer Reset
Alarm / Opto-Coupled Scaled Pulse
Forward / Reverse Flow Indication
FIGURE 4-1 shows the location of the jumper block on the circuit board assembly.
4-2
J1 Terminals to
Input / Output be Connected
Input 7-8, 4-6 and 3-5
Output 2-4, 1-3 and 8-10
Output 2-4, 1-3 and 7-9
Pulsed DC
CIRCUIT DESCRIPTION