Both Alarm Siren And Automatic Machinery Shutdown Using Two Switches - PCB Piezotronics IMI SENSORS 686 Series Installation And Operating Manual

Both Alarm Siren and Automatic Machinery Shutdown Using Two Switches

Figure 22 – Both Alarm Siren and Automatic Machinery Shutdown Using Two Switches
The Smart Switches are hooked up for providing alarm siren and automatic motor shutdown when the alarm
threshold levels are exceeded. To accomplish this, the two switches have two different threshold values; one for
alarm and one for shutdown. Pushing the Start pushbutton closes the M contact, and since RL2 contacts are
normally closed, starts the motor. If the start-up delay option for the switch is enabled, the switch will not trip
regardless of the vibration level during the specified delay time. After this delay, if the vibration level exceeds the
alarm threshold for the alarm switch, it will be activated and apply a voltage to the alarm siren. Since the NL (non-
latching) option is specified for this switch, the alarm siren will be energized until the vibration level falls below the
alarm threshold value (based also on the specified hysteresis). If the vibration level exceeds the shutdown alarm
threshold, the second vibration switch will be activated and apply a voltage to the RL relay coil. This will open the
RL contacts and shut down the motor. Since the LA (latching) option is specified, the RL coil will be constantly
energized after this event; even though the vibration level will drop below the alarm threshold value after
shutdown. The Reset pushbutton should be pushed to reset the switch and close the RL contacts before
restarting the motor.
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