FCI MT100 - Troubleshooting the Flow Element; Table 24 - Flow Element Resistance Measurements (in Ohms) Taken from Remote Electronics; Table 25 - Flow Element Resistance (in Ohms) at the Local Enclosure (MT100 S, Single Sensor Application)

MT100 Multipoint Flow Meter TROUBLESHOOTING
Troubleshooting the Flow Element
Check the Resistance of the Flow Element
Turn flow transmitter power OFF. Remove the TBx connector plug from all sensor wiring pin sockets in the remote enclosure (pull plug
straight out).
● TB1 (Sensor 1), TB2 (Sensor 2), TB3 (Sensor 3), TB4 (Sensor 4)  on main SB4 board
● TB1 (Sensor 5), TB2 (Sensor 6), TB3 (Sensor 7), TB4 (Sensor 8)  on extension SB8 board
Refer to the appropriate wiring diagram in APPENDIX A, page 97. With the TBx connector plugs still removed measure the resistance
between the terminals of terminal block TBx and compare with the values shown in Table 24 below.
Table 24 – Flow Element Resistance Measurements (In Ohms) Taken From Remote Electronics
Term
Number
TBx-1
(Htr Exc)
TBx-2
(Htr Rtn)
TBx-3
(Act Exc)
TBx-4
(Act Sen)
TBx-5
(Gnd Sen)
TBx-6
(Gnd)
TBx-7
(Ref Exc)
TBx-8
(Ref Sen)
TBx-1
(Htr Exc)
N/A 115
3
∞ ∞ ∞ ∞ ∞ ∞
TBx-2
(Htr Rtn)
115
3
N/A ∞ ∞ ∞ ∞ ∞ ∞
TBx-3
(Act Exc)
∞ ∞ N/A 0
1
1080
2
1080
2
2160
2
2160
2
TBx-4
(Act Sen)
∞ ∞ 0
1
N/A 1080
2
1080
2
2160
2
2160
2
TBx-5
(Gnd Sen)
∞ ∞ 1080
2
1080
2
N/A 0
1
1080
2
1080
2
TBx-6
(Gnd)
∞ ∞ 1080
2
1080
2
0
1
N/A 1080
2
1080
2
TBx-7
(Ref Exc)
∞ ∞ 2160
2
2160
2
1080
2
1080
2
N/A 0
1
TBx-8
(Ref Sen)
∞ ∞ 2160
2
2160
2
1080
2
1080
2
0
1
N/A
Notes: 1. Theoretical zero-ohm table values are influenced by sensor cable length, which typically adds <2 Ω.
2. Resistances are approximate for a sensor temperature of 70 °F (21 °C).
3. Heater resistance tolerance is ±10 Ω.
Note:
There is added resistance to consider when measuring the flow element from the remote transmitter. The cable adds
extra resistance. The added resistance can be found by measuring the ACT SEN wire to the ACT EXC wire (for
example: TB3-4 to TB3-6, orTB4-4 to TB4-6 etc.).
If the measured values do not match the above tables unplug the cabling connecting TBx to the flow element assembly and measure the
resistance between the terminals of flow element assembly terminal strip TSx (x=1, 2, 3 or 4). Compare the measured values with the
values shown in Table 25 or Table 26 as applicable to your installation.
Table 25 – Flow Element Resistance (in Ohms) at the Local Enclosure (MT100S, Single Sensor Application)
Terminal
Number
1 2 3 4 5
1
N/A
115
1
∞
∞
∞
2
115
1
N/A
∞
∞
∞
3
∞
∞
N/A
1080
2
2160
2
4
∞
∞
1080
2
N/A
1080
2
5
∞
∞
2160
2
1080
2
N/A
Notes: 1. Heater resistance tolerance is ±10 Ω.
2. Resistances are approximate for a sensor temperature of 70 °F (21 °C).
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