Tecfluid LTDR Series - Manual (Page 12)

12
9 ELECTRICAL SPECIFICATIONS 4-wire system
Output functions
continuous level measurement through analog output and
point level detection through switching output
Analog output (active)
current output 4…20 mA
the span between the lower range value [4mA] and the upper range value
[20mA] is equal to 0...100% of the continuous level measurement reading. It
is recommended that the span between those two range values stays within
the measuring range [M] (see figure 10)
Total load resistance
<500 Ω: HART TM resistor approx. 250Ω + load resistance approx. 250Ω
if the current output is connected to a device with an inner resistance of ap-
prox. 250 Ω, then there is no additional, external HART resistor necessary. In
that case, the HART modem is connected in parallel to the current output
wires
Lower range value 4,0 mA (span 0%)
Upper range value 20,0 mA (span 100%)
Response time 0,5 s (default), 2 s, 5 s (selectable)
Temperature drift <0,2 mm/K change in ambient temperature
Switching output DC PNP (active) NC or NO (short-circuit protected)
Load current <200mA
Signal voltage HIGH supply voltage - 2 V
Signal voltage LOW 0 V…1 V
Response time <200 ms
Supply voltage 12…30 VDC (reverse-polarity protected)
Current consumption <70 mA at 24 VDC (no burden)
Start-up time <6 s
Cable terminals
screwless, cage clamp terminal block for stranded and
solid wires 0,5…2 mm²
the usage of cable end sleeves with insulation collar is not recommended
10 APPLICATION SPECIFICATIONS continuous level measurement and point level
detection in liquids
Dielectric constant [ε
r
] single rod probe and rope probe: >1,8 coaxial probe:>1,4
Conductivity no restrictions
Density no restrictions
Dynamic viscosity
single rod probe and rope probe: <5.000 mPa s = 5.000 cP
coaxial probe: <500 mPa s = 500 cP
Application temperature -40°C…+150°C
Ambient temperature operation: -25°C…+80°C storage: -40°C…+85°C
Application pressure -1bar...40 bar
Velocity of level change <1.000 mm/s
Interface (e.g. oil on top of water)
an oil layer of <70mm thickness on top of water is not detected by the sensor;
in this case the sensor will detect only the water level at a slightly lower posi-
tion than actual. From an oil layer thickness >70mm onwards, the sensor
detects the total level, including the oil layer, according to specifications