5.3 Static Test
If improper operation of the magnetic flowmeter is suspected, the following resistance measurements
can be made to establish whether an electrical malfunction has occurred. A standard multimeter is
suitable for making the resistance checks. These measurements can be made at the Connection
board located in the base of the electronic housing.
WARNING
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.
5.3.1 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 "MR" (or "M3") on the Connection board in the meter
electronics base.
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 Connection board.
If a remotely mounted signal converter was supplied, proceed to step 1. If the magnetic flowmeter is
supplied with an integrally mounted signal converter, loosen and remove the four screws that hold the
signal converter to the base. Disconnect the plugs supplying signal (P1) and power (P3) connections
to the converter and set the converter aside. This will enable access to the Connection board.
1) Set the ohmmeter to its lowest range; e.g., R x 1.
2) Connect the Ohmmeter test leads to terminal lugs M1 and MR (or M3) on the Connection board.
The value displayed should correspond to the coil-resistance value indicated in Table 5-1 (
±
20%).
3) Connect the Ohmmeter test leads to terminal lugs CT and MR (or M3). The value displayed should
correspond to 1/2 the coil-resistance value indicated in Table 5-1 within
±
20%.
4) Connect the Ohmmeter test leads to terminal lugs CT1 and M1. The value displayed should
correspond to 1/2 the coil-resistance value indicated in Table 5-1 within
±
20%.
TABLE 5-1. PRIMARY COIL RESISTANCE
Meter Size Coil Resistance,
M1 to MR/M3
inch mm Ohms (nominal)
1
⁄
10
318
5
⁄
32
418
1
⁄
4
618
3
⁄
8
10 18
1
⁄
2
15 45
125 54
1
1
⁄
2
40 48
250 48
380 54
4 100 62
10D1475 MINI-MAG MAGNETIC FLOWMETER INSTRUCTION MANUAL
MAINTENANCE 5-3
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