User's Manual

Electrical Connection
42 A3276-8.0 HBM: public T40FM
Special electronic coding methods are used to protect the
purely digital signal transmission between the transmitter
head and the rotor from electromagnetic interference.
The cable shield is connected with the transducer hous
ing. This encloses the measurement system (without the
rotor) in a Faraday cage when the shield is laid flat at
both ends of the cable. With other connection techniques,
an EMCproof shield should be applied in the wire area,
and this shielding should also be connected extensively
(also see HBM Greenline Information, brochure i1577).
Electrical and magnetic fields often induce interference
voltages in the measuring circuit. Therefore:
S Use shielded, low-capacitance measurement cables
only (HBM cables fulfill both conditions).
S Only use plugs that meet EMC guidelines.
S Do not route the measurement cables parallel to
power lines and control circuits. If this is not possible,
protect the measurement cable with e.g. steel con
duit.
S Avoid stray fields from transformers, motors and con
tact switches.
S Do not ground the transducer, amplifier and indicator
more than once.
S Connect all the devices in the measuring chain to the
same protective earth conductor.
S In the case of interference due to potential differences
(compensating currents), the connections between
supply voltage zero and housing ground must be
broken at the amplifier and a potential equalization
line established between the stator housing and the
amplifier housing (copper conductor, at least 10 mm
2
wire crosssection).