11 MIC 1161 Manual
“Cross Talk” is due to the EMF (Electro Magnetic Flux) emitted by a wire as
current passes through it. This EMF can be picked up by other wires run-
ning in the same bundle or conduit.
In applications where a High Voltage Transformer is used (i.e. ignition sys-
tems) the secondary of the transformer should be isolated from all other
cables.
This instrument has been designed to operate in noisy environments, how-
ever, in some cases even with proper wiring it may be necessary to sup-
press the noise at its source.
2.2.1.4 USE OF SHIELDED CABLE
Shielded cable helps eliminate electrical noise being induced on the wires.
All analog signals should be run with shielded cable. Connection lead
length should be kept as short as possible, keeping the wires protected by
the shielding. The shield should be grounded at one end only. The pre-
ferred grounding location is the sensor, transmitter or transducer.
2.2.1.5 NOISE SUPPRESSION AT THE SOURCE
Usually when good wiring practices are followed no further noise protection
is necessary. Sometimes in severe electrical environments, the amount of
noise is so great that it has to be suppressed at the source. Many manu-
facturers of relays, contactors, etc. supply “surge suppressors” which
mount on the noise source.
For those devices that do not have surge suppressors supplied, RC (resis-
tance-capacitance) networks and/or MOV (metal oxide varistors) may be
added.
Inductive Coils - MOV’s are recommended for transient suppression in
inductive coils connected in parallel and as close as possible to the coil.
See Figure 2-4, page 12. Additional protection may be provided by adding
an RC network across the MOV.
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