Document 9162
Manual - ST5484E 2-Wire Seismic Vibration Transmitter
Page 4 of 7
Rev. T (Oct 2013)
4. Electromagnetic Compatibility
In order to meet the requirements of electromagnetic compatibility in areas of high electromagnetic interference, the field
wiring must be:
•
Shielded twisted pair cable enclosed in grounded metallic conduit, or
•
Double shielded twisted pair cable with a metallic body cable gland fitting and with the outer shield grounded.
Use standard two-conductor, twisted pair, shielded wiring for the long run to the instrumentation enclosure. The transmitter
is connected like any other loop-powered end device.
NOTE:
Metrix also strongly recommends the use of our ferrite bead kit (p/n 100458) as an extra precaution against
electromagnetic interference that may be induced in field wiring from subsequently bleeding into the transmitter. Refer to
best practices document 100459 for additional information, available at www.metrixvibration.com.
5. Connection to PLC or other Indicating Instrument
The first step in configuring the PLC, DCS, or other recording instrument is to determine the source of power.
The ST5484E requires loop power. Some analog input channels on a PLC or DCS, for example, provide this power from within.
If they do not provide power, an external power supply must be provided. Connect the transmitter field wiring using
standard instrumentation practices.
Scaling of the display is on the basis of the range of the
transmitter. The measurement parameter name is
“vibration” and the units are “in/s” (inches per second) or
“mm/s” (millimeters per second). The example at right is
based on a standard 1.0 in/s transmitter.
Momentary “jolts” that can occur at start-up, or during some operating condition changes, do not reflect a machine’s steady-
state operating condition. In order to prevent such occurrences from generating nuisance alarms, program a time delay into
the alarm such that the indicated vibration level must persist above the alarm setpoint for a preset period of time before an
alarm is generated. The indicated vibration level must cross the threshold level and stay above it for a preset time before any
alarm action is taken. A 2- to 3-second delay is normally applied to most machinery. Consult Metrix if you have a question
about your machine’s operating characteristics.
Some rough starting machinery may also need a start-up time lockout for alarms. A start-up lockout is different than a time
delay. A start-up lockout functions the same as a time delay, but is usually set to a much longer time. Both may be needed.
When vibration level
at transmitter is…
Transmitter
output will be…
PLC (or other)
should read…
0.0 in/s
(i.e., no vibration)
4.0 mA
(± 0.1 mA)
0.00 in/sec
1.0 in/s
(i.e., full scale
vibration)
20.0 mA
(± 0.5 mA)
1.00 in/sec