ABB K-MAG 10D1476 Instruction Manual page 48

10D1476 K-MAG MAGNETIC FLOWMETER INSTRUCTION MANUAL
3. Possible causes of erroneous flow rate indication are:
• incorrect grounding
• excessive noise due to a heavy slurry process
or a non-homogeneous process
• loose or intermittent wiring
• non-full or empty meter pipe
• excess air entrained in process liquid
6.3 Static Test
If improper operation of the Magnetic Flowmeter is suspected, the following resistance measure-
ments can be made to establish whether an electrical malfunction has occurred. A standard multime-
ter is suitable for making the resistance checks. These measurements can be made at the Primary
Board located in the Flowmeter electronics base.
Equipment that operates from ac line voltage constitutes a potential
electric shock hazard to the user. Make certain that the system power is
disconnected before making the following ohmmeter checks.
6.3.1 Magnet Coil Check
There are two magnet coils in the meter that are connected in a series arrangement. The respective
coil leads are brought up to lugs "M1 and CT1" and "CT and MR" on the CMF board in the meter
electronics base. (Note that terminals CT and CT1 are internally connected via printed circuit path.)
Figure 5-1 shows the actual connection method.
Before making resistance measurements, verify that the system power service has been de-ener-
gized. Remove the electronics housing cover to obtain access to the CMF board.
Since the 10D1476 is a remote-mounted Signal Converter, proceed to step 1).
1) Set the ohmmeter to its lowest range; e.g., R x 1.
2) Connect the Ohmmeter test leads to terminal lugs M1 and CT1 on the CMF board. The value
displayed should correspond to 1/2 of the value ( ± 20%) indicated in Table 6-1.
3) Connect the Ohmmeter test leads to terminal lugs CT and MR. The value displayed should
correspond to that obtained in Step 2 and as indicated in Table 6-1 within ± 20%.
If proper coil resistance is measured, it can be assumed that the magnet coils are functional. If the
measurement indicates that either or both coils are "open" (infinite resistance), the Magnetic Flowme-
ter must be replaced.
4) Carefully unsolder the four coil wires from the terminal lugs on the CMF pc board. Identify each
wire to enable its proper reconnection.
WARNING
6-3