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TROUBLESHOOTING
Heater Current Check
The heater current can be checked at TP1 on the FES-200. Set the DMM to DC volts (V).
1. Connect the positive lead of the DMM to TP1 on the FES-200.
2. Connect the negative lead of the DMM to the HTR EXC terminal of the flow transmitter.
The measured mV value of heater current will be 10x larger than the actual mA heater current. For example, 750 mV indicates 75 mA
heater current. The measured value of heater current must be within ±0.15 mA of the factory set value. See Table 28 below.
FCI Transmitter Model
MT100S, S-type sensor probe
MT100S, F-type sensor probe
MT100M, mast style probe
Allowable Limits
Example 1 - 4-20 mA output check using 1-5 VDC measurement.
Accuracy:
Example Delta R Table entry:
Delta R (ohms)
71.08
•
Measure VDC with FES-200 thumbwheel set to 071.08 = 3.011 VDC measured on DMM.
•
Determine allowable VDC limits for the 2.995 VDC table value:
Note:
•
Allowable VDC limits = 0.0075 x (2.995 – 1) + 0.005 x (5 – 1) = ±0.035 VDC
The measured value of 3.011 VDC is within the allowable limits of 2.995 ±0.035 VDC.
Example 2 - 4-20 mA output check (using example 1 sample data)
•
Measure mA with FES-200 thumbwheel set to 071.08 = 12.04 mA measured on DMM.
•
Determine allowable mA limits for the 11.98 mA table value:
Note:
•
Allowable mA limits = 0.0075 x (11.98 – 4) + 0.005 x (20 – 4) = ±0.139 mA
The measured value of 12.04 mA is within the allowable limits of 11.98 ±0.139 mA.
Example 3 - Indicated Display Check (using information from above examples)
•
Record the indicated display value with FES-200 thumbwheel set to 071.08 = 156 SCFM indicated on display.
•
Determine allowable limits for the 154.8 SCFM table value:
Note:
•
Allowable Indicated flow limits = 0.0075 x 154.8 SCFM + 0.005 x 310 SCFM = ± 2.71 SCFM
The indicated value of 156 SCFM is within the allowable limits of 154.8 ±2.71 SCFM.
94
±(0.75% reading + 0.5% full scale) from GF90 Manual
VDC Across
250 ohms
2.995
Since the 1-5 VDC range starts at 1 VDC, account for this offset by subtracting 1 VDC from both the "reading" of
2.995 VDC and the "full scale" of 5 VDC.
Since the 4-20 mA range starts at 4 mA, account for this offset by subtracting 4 mA from both the "reading" of 11.98
mA and the "full scale" of 20 mA.
The full scale display value is 310 SCFM in this example.
Table 28 – Heater Current
Factory-set Heater Current
90 mA
75 mA
mA Output
11.98
MT100 Multipoint Flow Meter
DMM Reading
900 mV
750 mV
Unit dR
Indicated
Display
71.197
154.8 SCFM
Fluid Components International LLC
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Table of Contents
Troubleshooting
