KROHNE BM 702 - Ex-e Current Output HART (BM 70 A;P); Ex-i (IS) Current Output HART (BM 70 A;P); Ex-i (IS) Current Output HART (BM 702)

BM 70 X Project Engineering Guidelines 01/2001 Page: 7
4.2 Ex-e current output HART
®
Function Level, distance, volume
FRQYHUVLRQWDEOHor reflection,
and error identification;
galvanically isolated from digital input and switching output
Current 4-20 mA; without or with error message 2 mA or 22 mA
Accuracy/linearity 0.05 % (rel. 20 mA; at T=20°C/68°F, 100Ω load and rated operating voltage)
Temperature drift ≤ 100 ppm/K (typically 30 ppm/K)
Load ≤ 500 Ω
Effect of load impedance ≤ 0.02 % (rel. 20 mA for R
B
= 0...500 Ω)
Effect of power ≤ 0.02 % (rel. 20 mA for U
B
within limits of tolerance)
Hazardous-duty version: Ex e
Note: Together with switching output and digital input
Digital input (terminals 81/82):
Can be used to interrupt the entire measuring procedure (measurements are suspended) or to hot
start the device.
Applicable voltage: 5...28 V DC
Input resistance: ≥ 1 kΩ
Switching output (terminals 41/42):
Can be programmed as limit switch, alarm contact or error message.
The contact is open in de-energized condition.
Operating data: max. 100 mA / 30 V DC or 30 V AC.
Internal resistance: ≤ 20 Ω
4.3 Ex-i (IS) current output HART
®
(type of protection: Ex de [ia])
BM 70 A, BM 70 P:
Function Level, distance, volume FRQYHUVLRQWDEOH or reflection;
and error identification;
passive output (current sink)
Current 4-20 mA; without or with error message 3.6 mA or 22 mA;
4 mA constant, adjustable for HART
®
-Multidrop
Temperature drift ≤ 100 ppm/K (typically 30 ppm/K)
Accuracy/linearity 0.05 % (rel. 20 mA; at T = 20°C/68°F, 10 V supply voltage
and rated operating voltage)
Supply voltage U 8-30 V (between terminals 31 and 32)
Load ≤ (U
S
- 8 V) / 22 mA (U
S
= external supply voltage)
Effect of supply voltage ≤ 0.02 % (rel. 20 mA for U = 8...30 V)
Effect of power ≤ 0.02 % (rel. 20 mA for U
B
within limits of tolerance)
Note: Digital input is not available.
Optional switching output (terminals 41/42):
can be programmed as limit switch, alarm contact or error message.
The contact is open in the de-energized condition.
Operating data: 6...30 V; I
Low
≤ 110mA; U
Low
≤ 2V; I
High
≤ 900 µA (U=30V) and I
High
=
200 µA (U=8V)
Ex-i safety limits
Signal circuit in type of protection: Intrinsic Safety EEx ia IIC/IIB or EEx ib IIC/IIB
for connection to a certified intrinsically safe circuit with the following peak values:
U
i
= 30 V; I
i
= 250 mA; P
i
= 1 W
Effective inner capacitance C
i
≈ 0; effective inner inductance L
i
≈ 0
BM 702:
Function Level, distance or volume (conversion table); and error identification;
passive output (current sink)
Current 4-20 mA; without or with error message 3.6 mA or 22 mA;
4 mA constant, adjustable for HART
®
-Multidrop
Temperature drift ≤ 100 ppm/K (typically 30 ppm/K)
Accuracy/linearity 0.15 % (rel. 20 mA; at T = 20°C/68°F, 24 V terminal voltage)
Supply voltage U 13-30 V (between terminals); U
min
dependent on current (see Sect. 9.1)