Metrix 5550 User Manual

Doc# 1231558 • REV C (November 2017) Page 3 of 20
1.3 Primary Variables Aecng 5550 Operaon
The required seismic acceleraon to move the 5550 or 5550G mechanical switch from its un-
tripped posion to its tripped posion is a funcon of three variables as detailed in secons
1.3.1 through 1.3.4.
1.3.1 Variable #1 – Spring Force Direcon
The movable trip plate mass inside the switch housing is
free to move on an essenally friconless pivot, and is
restrained in its untripped posion by a spring. By turning
the setpoint adjustment screw (Figure 3), changes are made
to the spring’s direcon, and to a much lesser extent, its
tension. Thus, the spring mechanism exerts an essenally
constant force on the trip plate and turning the setpoint ad-
justment screw changes the direcon of this force. Turning
the setpoint screw clockwise (CW) aligns the spring force
more fully in the untripped direcon (below the pivot – see
Figure 1), making it more dicult to trip the device. Turn-
ing the setpoint screw counter-clockwise (CCW) does the
opposite, making it easier to trip the device.
SETPOINT
ADJUST
RESET PLUNGER
FIGURE 3: MODEL 5550 setpoint
adjustment and manual reset.
NOTE: Metrix Mechanical Vibraon Switches
are not intended for use on high-speed tur-
bomachinery or on machines where changes in
seismic acceleraon smaller than 1G must be
reliably detected. Instead, Metrix oers more
sophiscated electronic vibraon sensing soluons that
are beer suited for such applicaons.
NOTES:
1. Turning the screw too far in the counter clockwise (CCW) direcon will eventu-
ally pull the spring past the over-center locaon and cause the switch to snap
into the tripped posion without any external ineral excitaon. When adjusted
in this manner, the switch cannot be reset from its tripped posion. Also, the
nature of this over-center mechanism can cause it to be very unstable when adjusted too
close to its equilibrium locaon, resulng in false trips.
2. The setpoint adjustment screw on the model 5550G switch is not externally accessible.
The cover must be removed. Do not remove the cover while energized circuits are pres-
ent in hazardous areas
1.3.2 Variable #2 – Switch Orientaon
Depending on how the switch is oriented, gravity will act on the trip mechanism’s mov-
able mass to either add to or subtract from the spring force. For both model 5550 and
5550G switches, the switch orientaon is the direcon in which the cover faces. With the
switch oriented horizontally (Figure 4A), the eects of gravity will be negligible and only

Metrix 5550 Specifications

General

Brand	Metrix
Model	5550
Category	Switch
Language	English