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description
Introduction
The single set point model contains one trip limit for shutdown. The optional
dual set point model contains two independent trip limits; one for alarm and
one for shutdown. Shutdown and Alarm trip is set in velocity. In addition, a
4-20 mA output proportional to vibration level is provided.
The 440 and 450 performance, wiring, and specifications are identical except
for the enclosure. The 440 meets NEMA 3, 4 and 12. The 450 meets these
and certain explosion proof specifications.
Protection of Rotating and Reciprocating Machinery
A system is required which is responsive to faults which:
1—present themselves as low frequency vibrations such as imbalance, misalign-
ments, defective sleeve bearings, broken tie down bolts, etc.
2—present themselves as higher frequency vibrations such as defective ball
or roller bearings, gear mesh, blade pass frequencies, and in the case of re-
ciprocating machinery, detonation and broken parts.
Velocity is the optimum parameter for both high and low frequencies, since it
is equally sensitive to both. Acceleration (as with mechanical switches) is over
sensitive to the high frequencies and very insensitive to the low frequencies.
On machines operating at very low RPM (100 - 200 RPM), displacement may
also be suitable.
Time delay is absolutely essential in any usable vibration monitor. Virtually
all machines will exhibit high vibration for several seconds during startup. If
time delay is not provided, the operator must turn up the trip point to get thru
startup. The resultant setting will be too high to provide protection during nor-
mal running. This is one reason there are so many cases where machines with
mechanical type vibration switches have not tripped. Time delay is included in
the Solid State Model 440.
Summary of Capabilities
Refer to Panel Control
1—Trip is based on vibration severity. The internal sensor (unless the external
sensor option has been purchased) is a piezoelectric crystal with built-in mi-
croelectronics to reduce noise sensitivity. The output signal is electronically
integrated to measure and trip on velocity or displacement.2—Calibrated set
