Parameterization
D184B140U02 FSM4000
89
7.4.1.3 Determining the coil temperature
The coil temperature is a function of the ambient and fluid temperatures. The measurement can,
e.g., be used to monitor overtemperature due to the fluid.
The coil temperature is measured indirectly via the coil DC resistance.
To perform the measurement, it is necessary to switch on one of the relevant errors or warnings
in the submenu "Diagnostics/Alert Settings".
T
Coil
=
C
R
R
R
f
f
f
Coil
°
+
•
−
20
Re
Re
Re
α
T
Coil
Coil temperature
R
Coil
Coil resistance
R
Ref
Reference coil resistance at 20 °C
f
Re
α
Temperature coefficient of copper at
20 °C (0.39%/K)
Important
The coil resistance of the flowmeter sensor must be adjusted at a reference temperature. This
applies to newly shipped systems SE41F / SE21 and S4. When connecting an S4 transmitter
to already shipped sensor SE41F / SE21, it is necessary to perform the adjustment. For
additional information, see chapter "7.4.3 Readjusting the coil temperature".
7.4.1.4 Determining the insulation resistance for the coil
G00578d
Detecting problems with the coil insulation. Can be caused,
e.g., by moisture in the flowmeter sensor or in the connection
box.
When determining the insulation resistance of the coil to
ground, a DC field test signal of approx. 1 sec is sent to the coil,
separating the ground connection in the transmitter. In spite of
the separation provided by the coil, the current flowing to
ground is used to calculate the insulation resistance.
During this measurement, the flowrate cannot be measured and
the last valid flowrate value is retained.
To perform this test, it is necessary to switch on one of the relevant errors or warnings in the
submenu "Diagnostics/Alert Settings" (see page 80).
