User Manual

Installation and operating instructions BM 70 A/P Page: 72 11/00
Annex A: Technical data
1 Range of application Distance, level, volume and reflection measurement of liquids, pastes,
slurries, solids and particulate material on storage and process tanks or
containers made of metal or concrete, and also in stilling wells
2 Mode of operation / system structure FMCW-Radar in the X-Band (8.5-9.9 GHz) with digital signal processing;
compact device, modular design
3 Input
Measured variable Primary variables: distance, reflection; derived variables: level, volume
Measuring range Min. tank height: 0.5 m
max. measuring range: 40 m (optionally upto 100m); Wave-Stick: 20 m,
BM 70 P = 35m
Block distance
Min. 0.2 to 1.0 m; see Sect. 3.3
Rate of change in level
≤ 10 m/min; BM 70 P ≤ 1m/min
4 Output
Variant 1
Ex-e current output HART
®
Type
Current range
Accuracy/linearity
Temperature drift
Load impedance
active (current source); Ex-e
4-20 mA (error: 2 mA or 22 mA)
0.05 % (rel. 20 mA; 25°C)
≤ 100 ppm/K (typically 30 ppm/K)
≤ 500 Ω
with switching output:
and digital input:
max. 100 mA / 30 V DC or 30 V AC; internal resistance ≤ 20 Ω; potential-
free
to "freeze" the measured value; voltage: 5 to 28 V DC;
input resistance: ≥ 1 k Ω; potential-free
Variant 2
Ex-i current output HART
®
Type
Current range
Temperature drift
Accuracy/linearity
Supply voltage
Load impedance
passive (current sink); Ex-i
4-20 mA (error 3.6 or 22 mA);
4 mA constant for HART
®
-Multidrop
≤ 100 ppm/K (typically 30 ppm/K)
0.05 % (rel. 20 mA; 25°C)
8-30 V (terminals 31 and 32)
≤ (U
S
- 8 V) / 22 mA, (U
S
= external supply
voltage)
with optional switching output:
6 ... 30 V; I
Low
≤ 2 V; I
High
≤ 900 µA (U = 30 V), I
High
= 200 µA (U = 8 V)
Variant 3
RS 485 interface
Transmission rate
Address:
Protocols:
1200 to 38400 bauds
0 to 255
KROHNE Protocol,
Modbus-RTU, HART
®
with additional current output Type
Current range
Accuracy/linearity
Temperature drift
Load impedance
When operated as switching
output:
active (current source); not communicable;
Ex-e
4-20 mA (error 2 mA or 22 mA)
0.3 % (rel. 20 mA; 25°C)
≤ 200 ppm/K (typically 70 ppm/K)
≤ 250 Ω
Low: I < 2 mA; High: I = 22 mA
(R ≤ 250 Ω) and no-load voltage ≤ 18 V
Variant 4: PROFIBUS-PA (Ex-i)
Hardware
Physical
Bus characteristics
Base current
Default current
to IEC 61 158-2 and the FISCO model
9 ... 30 V; 0.3 mA max.; 4.2 W max.
10 mA
6 mA
Variant 5: Foundation Fieldbus (FF)
see Supplementary Instructions
Breakdown signal
Current output: error signal 2/22 mA or 3.6 mA (Ex-i),
plain text in local display
Switching contact: opening or closing of the contact
Digital interfaces: error flags
5 Measuring accuracy
Error of measurement Reference conditions and error curves: see Sect. 5.1 and 5.2
Repeatability
≤ 0.5 × error of measurement
Measured-value resolution
BM 70 A: 1 mm; BM 70 P: 0.1 mm
Effect of ambient temperature
No significant effect on measured value(- 1 ppm/°C);
(see also signal outputs)
6 Operating conditions
6.1 Installation conditions Avoid interference reflections and multiple reflections
6.2 Ambient conditions
Hazardous locations
BM 70 A/P Ex: Zone 0,1,2; IIC/IIB, T6...T2
Ambient temperature at signal converter -20...+55°C (-24...+131°F)
Functional range: -40...+70°C (-40...+158°F)
Flange temperature
Horn antenna, Wave-Guide (Tamb ≤ 50°C/122°F): -30...+130°C
(
-22...+266°F)