A useful feature that has been incorporated into the latest versions of the Super Seal™ is the Adjustable LSI function. It provides the operator with the ability to establish a level or threshold for the LSI circuit to operate an alarm.
If the output as displayed on the digital meter falls below the operator determined set point, the LSI relay contacts will change state. These contacts are provided to warn the operator that the induction sealing power level has dropped below the alarm threshold set point. The alarm contacts may be used to switch power to a warning light or activate an audible alarm.
To accomplish an induction seal, the power supply power level must be set to a sufficient level to melt the polymer layer on the foil, developing a bond between the container and the foil seal. The LSI threshold should be set below this minimum output power level. In the event the power supply operating power level is either adjusted, or falls below the LSI threshold level, the LSI circuitry will activate the LSI relay, effectively functioning as an on/off switch for the alarm.
During normal operation, if the output level falls below this set point the RUN indicator light will extinguish and the LSI relay contacts will change state. It is important to note that the LSI Alarm by itself will not interrupt operation of the power supply, even though there may be insufficient power to develop an adequate seal.
When the output is adjusted fully downward the power supply will operate at a minimum level necessary to develop the magnetic field. This level is dependent on the cap sealer model. For the Super Seal™ 50 it is 55%, the Super Seal™ 75 is 40%, and the Super Seal™ 100 is 35% of maximum power level. The LSI threshold level must be set above the minimum power level to be effective.
How to set up the LSI
Once the effective sealing power level has been determined, the LSI level can be selected and entered from the front panel of the power supply. To set the threshold level, turn on the circuit breaker. The output meter indication should be flashing. Enter the desired threshold level using the UP/DOWN arrows on the front panel. Once the level is selected, press and hold the STOP button, then press the DOWN arrow. The LSI threshold level is now set. When the START button is pressed and the operating power level is above the LSI threshold, the meter indication will not flash.
With the stack light option, the adjustable LSI set point will be visible by the changed state of the stack light itself. When operating above the established threshold the light will be green. When the output is below the threshold, the light will change to flashing red to indicate an alarm status. When the Super Seal is powered up, but in a stopped condition, the status light will be flashing red.
Optional Stack Light
Newer Super Seal™ models provide an internal 24-volt DC power source to operate the optional Stack Light. This 24V DC supply is also used by other options.
Internal circuitry will flash a red light when no output is being delivered to the sealing head or if the Adjustable LSI is set below the threshold level.
During normal operation, the Stack Light will illuminate a green light when output is delivered to the sealing head.
Originally appeared in: eMaintenance: Induction Sealing Technology 1st Quarter 2003