ABB K-MAG 10D1476 Instruction Manual page 43

10D1476 K-MAG MAGNETIC FLOWMETER INSTRUCTION MANUAL
5.3 Jumper Selections
For remote converters, zero return and functions associated with the 50XM1000 signal converter are
established by the 686B623U01 Primary Board assembly, shown in Figure 5-2.
Settings are determined by movable jumpers at terminals A2 and B1 located on the lower left corner
of the 686B623U01 assembly. The diagram and table that follow the figure correlate the zero return
and other functions with the jumper settings.
A circuit schematic of the primary CMF board is shown in Figure 5-3. The meter calibration factor is
established by a voltage division off the R5 current sensing resistor, first by a coarse network
consisting of R6 through R12, and then by a fine adjustment via potentiometer R14. These values
may only be re-established by noting the open positions of shunt S1 and measuring (out of circuit) the
values of R14 (each end to wiper) and R15.
System zero is established with the aid of transformer T1, through whose primary winding the magnet
coil current flows. The center tap connection of the respective secondary windings of T1 are
connected in series with each electrode signal.
One secondary winding removes the voltage impulse from electrode signal 2 which occurs as a result
of coil voltage reversal (see waveform). This signal is factory adjusted to a minimum, using an
oscilloscope connected to the input amplifying system of the Converter. The adjustment is very
sensitive and thus extreme care must be exercised when setting potentiometer R3.
Electrode circuit 1 receives a signal from the other secondary winding, and is integrated via capacitor
C2 and potentiometer R2 so as to produce a square wave. This adjustment removes residual offset
not corrected by the previous adjustment.
The magnet coils are driven (see Figure 5-1) via the connection of J3 to P3, while the 686B630
Adaptor Board routes the reference and electrode signals to the proper positions of J1, J2, and their
corresponding RFI filters (see INSET, Figure 5-3).
Refer to the instruction manual provided with the Signal Converter for interconnection wiring.
5-3