Functional Description - ABB MINI-MAG 10D1475 Instruction Manual

10D1475 MINI-MAG MAGNETIC FLOWMETER INSTRUCTION BULLETIN
The Flowmeter without the electronics package is used with a remote Signal Converter. A remote
mounted Signal Converter is recommended if:
• The integral model vibration specification is exceeded and/or
• The process liquid temperature exceeds the value given for that ambient
temperature listed in the integral model's specifications.
Figure 1-2 shows a remote Primary used for general purpose and FM Class I, Div.2 applications. A
2-piece box with cable seal and pressure-relief fitting is shown. Figure 1-3 shows the remote Primary
with cable seal used for FM Class I, Div.1 applications.
FIGURE 1-2. REMOTE PRIMARY w/
GENERAL PURPOSE BOX
The Signal Converter also contains a magnet driver unit that is used to power the meter's magnet
coils. The steady state magnetic field principle, referred to as the MAG-X
optimum zero point stability at an optimized frequency which is a submultiple of the power line
frequency.
For additional detail, refer to Section 1.3.

1.2 Functional Description

The Magnetic Flowmeter body houses two signal electrodes and the flux producing magnet coils, as
shown schematically in Figure 1-4. All primary intraconnection wiring is terminated at a printed circuit
assembly located in the base of the meter housing.
In addition to having two energy limited electrode outputs, 10D1475J models and all primaries with
integrally mounted Converters contain a current sensing reference voltage network. Adjustment of
this network changes coil excitation current permitting "constant meter factors" to be derived from the
various size Primaries. For Primaries with remote mounted M2 converters (10D1475H), the reference
network provides a fixed 200 mA excitation current and is located on the base connection board of
the Signal Converter.
The reference voltage network is connected in series with the magnet coils. Changes in the magnet
drive voltage, which cause a proportional variation of flow signal, will simultaneously cause a similar
variation of the reference voltage. The reference circuitry will precisely track the magnetic flux in the
metering section. When measured along with electrode voltage by the signal converter, the refer-
ence voltage will provide immunity to system temperature or power supply variations.
1-2
FIGURE 1-3. REMOTE w/
EXPLOSION PROOF BOX
®
design concept, provides
INTRODUCTION