Notes For Cabling - HBM TB1A Montageanleitung

20

5.1 Notes for cabling

Electrical and magnetic fields often cause interference voltages to be injected
into the measuring circuit. This interference starts primarily from power lines
lying parallel to the measuring leads, but can also start from any contactors or
electric motors in the vicinity. In addition, interference voltages can be injected
galvanically, especially if the measurement chain is grounded at several
points.
Please take note of the following:
• Use only shielded and low capacitance measurement cables from HBM.
• Do not install measurement cables parallel to power lines or control
circuits. If this is not possible (e.g. in cable shafts), protect the
measurement cable by armoured steel tubing, for example and keep it a
minimum of 50 cm away from other cables. Power lines or control circuits
should be twisted together (15 twists per meter).
• The stray fields of transformers, motors and contactors should be avoided.
• Do not ground transducers, amplifiers and indicating instruments
repeatedly. All the devices of the measurement chain should be connected
to the same grounded conductor.
• The shield of the connection cable is connected to the transducer housing.
• Connection diagram, grounding concept (Greenline).
Grounding concept (Greenline).
The cable shielding is connected in accordance with the Greenline concept.
This encloses the measurement system in a Faraday cage. Any
electromagnetic interference active here does not affect the measurement
signal. Special electronic coding methods are used to protect the transmission
path from electromagnetic interferences.
In the case of interferences due to potential differences (compensating
currents), operating voltage zero and housing ground must be disconnected
on the amplifier and a potential equalization line between housing and
amplifier housing must be established (highly flexible stranded wire, 10 mm
wire cross section).
HBM
TB1A
2
A0162 7.0 en/de/fr