Metrix 5550 User Manual

Doc# 1231558 • REV C (November 2017) Page 16 of 20
NOTE: The reset coil circuit contains a thermistor that allows the circuit to
also funcon as a startup delay when voltage is connuously applied (see
secon 5.2). If the thermistor is hot, current will not ow and the reset
funcon will not operate. A cool-down period may be required (see Secon
5.2.1). In many applicaons, voltage is connuously applied to the reset coil ter-
minals while the machine is running. In such situaons, the thermistor will sll be
hot immediately following a trip and it will not be possible to electrically reset the
switch unl the thermistor has cooled suciently. If necessary, the switch can be
manually reset (5550 only), using the plunger pushbuon to allow a “hot” restart.
Alternavely, it may be desirable to program the machine’s control system to ap-
ply voltage to the reset coil for only 30 -40 seconds during machine start up. This
pracce will ensure that the thermistor is more likely to be “cold” following a trip,
allowing an immediate remote reset.
circuit as the output relay(s), allowing the 5550/5550G to be removed from the machinery
shutdown loop.
5.2 Startup Delay
The startup delay feature is intended for use in machines that exhibit high vibraon during
startup. This feature maintains the switch in an untripped posion for a factory pre-set
delay period of approximately 30 seconds, aer which the switch resumes normal operaon.
To acvate startup delay, connuously apply the specied voltage across the reset terminals
and the switch will be suppressed from tripping for the preset delay period, allowing the
machine to run up to operang speed and normal vibraon levels. Voltage must be connu-
ously applied for the duraon of the startup delay (approximately 30 seconds). If this volt-
age is removed prematurely, the coil will de-energize and the switch will not be suppressed
from tripping.
5.2.1 Thermistor Consideraons
The startup delay feature works through use of an internal thermistor in series with a sole-
noid mechanism. When voltage is connuously applied, current ows in the circuit and the
thermistor’s temperature rises, gradually restricng current ow. When the current drops
below the minimum value required to keep the coil energized, the solenoid retracts. Nor-
mally, it takes approximately 30 seconds for the thermistor to reach this “cut-o” tempera-
ture. However, several factors can serve to shorten or lengthen this interval as follows:
• Ambient Temperature Eects
The me for the thermistor to reach its cut-o value depends on the inial temper-
ature of the thermistor. If the switch is at an ambient temperature of -30C during
the winter months, it will obviously exhibit a longer startup delay than during the
summer months when ambient temperatures may be 30C. Likewise, if the switch is
placed on a machine that can sustain a large temperature rise at the mounng loca-
on, the switch may be near its maximum temperature rang of 70C aer a period
of prolonged operaon. This will shorten the startup delay interval when compared
to operaon on a “cold” machine.
WARNING: Voltages present at reset terminals can result
in serious injury or death. Always de-energize these
circuits prior to installaon or maintenance and use ap-
propriate lock-out / tag-out procedures where applicable.

Metrix 5550 Specifications

General

Brand	Metrix
Model	5550
Category	Switch
Language	English