KROHNE IFC 110 Converter - Manual (Page 8)

Sect. 1.3.1 Part A System installation and start-up
8 IFC 110 F 05/2003
1.3 Electrical connection of flow sensors
1.3.1 General remarks on signal lines A and B and field current line C
Proper operation of the equipment is ensured when KROHNE signal lines A and B are used with
foil screen and magnetic shield.
• Signal lines must be firmly installed.
• Shields are connected via stranded drain wires.
• Underwater or underground routing is possible.
• Insulating material flame-retardant to IEC 332.1 / VDE 0742.
• Low-halogen, unplasticized signal lines which remain flexible at low temperatures.
Signal line A (type DS) with double shielding
1 Stranded drain wire, 1st shield, 1.5 mm² or AWG 14
2 Insulation
3 Stranded wire 0.5 mm² or AWG 20 (3.1 red/3.2 white)
4 Special foil, 1st shield
5 Insulation
6 Mu-metal foil, 2nd shield
7 Stranded drain wire, 2nd shield, 0.5 mm² or AWG 20
8 Outer sheath
Signal line B (type BTS) with triple shielding (bootstrap line)
The bootstrap technology always controls the individual shields (3) of the signal converter exactly
to the voltage which is supplied to the signal conductors (5). As this prevents voltage differences
between the individual shields (3) and signal conductors (5), no current flows via the line
capacitances between 3 and 5. The line capacitance seems to become ”zero”.
This allows greater cable lengths in case the electric conductivity of the liquid to be measured is
low.
1
2
3
4
5
6
7
8
9
10
11
12 Dummy glider wire
Insulation (2.1 red/2.2 white)
Special foil, 1st shield (3.1/3.2)
Insulation (4.1/4.2)
Stranded wire 0.5 mm² or AWG 20
(5.1 red/5.2 white)
Stranded drain wire, 1st shield, 0.5 mm² or
AWG 20 (6.1/6.2)
Special foil, 2nd shield
Stranded drain wire, 2nd shield, 1.5 mm² or AWG 14
Insulation
Mu-metal foil, 3rd shield
Stranded drain wire, 3rd shield, 0.5 mm² or AWG 20
Outer sheath
Field current line C1
Line 2 x 0.75 mm² (18 AWG) Cu or 2 x (4 x) 1.5 mm² (14 AWG) Cu (Cu = copper cross section)
The cross section depends on the required cable length.
For max. permissible cable lengths please refer to Section 1.3.4
IMPORTANT!
For EEx versions, also pay regard to all directions included in Sect. 6.1 and 13.
Only the EEx flow sensor may be installed in the hazardous area. The EEx
certified signal converter must be installed outside the hazardous area!