Circuit Description - ABB 3000 Series Instruction Manual

5.0 CIRCUIT DESCRIPTION

The 10D1472 Flowmeter contains circuitry in the electronics housing which provides two functions:
• Establishes primary zero
• Normalizes the flow signal by generating a voltage proportional to coil current.
The magnetic flux in the metering system is directly proportional to the current through the metering
coils.
Zero adjustment is accomplished by using a potentiometer to null a magnetic flux loop located within
the flowmeter body. The meter calibration factor is established via the reference voltage (terminals 6
and 7). Current flowing through the coils is passed through a current transformer which has a load
impedance network on its output winding. The output signal across this impedance and the parallel
1000 ohm resistive load in the signal converter generate a reference signal which is in phase with the
electrode velocity signal and produces an appropriate meter calibration factor. Using current sensing,
the Converter will make a ratiometric measurement of flow velocity which is unaffected by variations
of line voltage or coil temperature.
All 10DS3111 are powered by a 110/120 VAC 50/60 Hz line source.
Refer to Figure 5-1 for electronic circuitry.
10DS3111A INSTRUCTION MANUAL
5-1