Non-Transducer Noise Sources; Common Wiring Problems; Reducing Electrical Noise; Reducing Acoustical Noise - Siemens MAG 1100 Operating Instructions Manual

Non-Transducer Noise Sources

Remove all input and output cables from the MultiRanger individually while monitoring
the noise. If removing a cable reduces the noise, that cable may be picking up noise from
adjacent electrical equipment. Check that low voltage cables are not being run adjacent
to high voltage cables or near to electrical noise generators such as variable speed
drives.
Filtering cables is an option but is not recommended unless all other options have been
exhausted.
The MultiRanger is designed to work near heavy industrial equipment such as variable
speed drives. Even so, it should not be located near high voltage wires or switch gear.
Try moving the electronics to a different location. Often moving the electronics a few
meters farther from the source of noise will fix the problem. Shielding the electronics is
also an option, but it should be a last resort. Proper shielding is expensive and is difficult
to install properly–the shielding box must enclose the MultiRanger electronics
completely, and all wires must be brought to the box through grounded metal conduit.

Common Wiring Problems

• Make sure that the transducer shield wire is connected at the electronics end only.
Do not ground it at any other location.
• Do not connect the transducer shield wire to the white wire.
• The exposed transducer shield wire must be as short as possible.
• Connections between the wire supplied with the transducer, and any customer
installed extension wire should be done in grounded metal junction boxes.
On Siemens Milltronics transducers the white wire is negative and the black wire is
positive. If the extension wire is colored differently, make sure that it is wired consistently.
Extension wire must be shielded twisted pair. Older MultiRanger products may have
included recommendations to use co-axial cable for noise reduction purposes. This is no
longer the case. Use shielded twisted pair. See the installation section for specifications.

Reducing Electrical Noise

• Ensure that the transducer cable does not run parallel to other cables carrying high
voltage or current.
• Move the transducer cable away from noise generators like variable speed drives.
• Put the transducer cable in grounded metal conduit.
• Filter the noise source.

Reducing Acoustical Noise

• Move the transducer away from the noise source.
• Use a stilling well.
• Install a rubber or foam bushing or gasket between the transducer and the
mounting surface.
• Relocate or insulate the noise source.
• Change the frequency of the noise. The MultiRanger is only sensitive to noise
between 25 KHz and 65 KHz.
7ML19981FB05 MultiRanger 100/200 – INSTRUCTION MANUAL Page 233