Application
Version 1
RES-407
Page 7
2
Application
This RESISTRON
®
temperature controller is an integral part of the "series 400", the outstanding feature of which
is its microprocessor technology. All RESISTRON temperature controllers are used to control the temperature of
heating elements (heatsealing bands, beaded bands, cutting wires, heatsealing blades, solder elements etc.), as
required in a variety of heatsealing processes.
The controller is most commonly used for impulse-heatsealing PE and PP films in:
• Vertical and horizontal f/f/s machines
• Pouch, filling and sealing machines
• Film wrapping machines
• Pouch-making machines
• Group packaging machines
• L-sealers
• etc.
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Principle of operation
The resistance of the heatsealing band, which is temperature-sensitive, is monitored 50x per second (60x at 60Hz)
by measuring the current and voltage. The temperature calculated with the help of these measurements is dis-
played and compared with the set point.
The primary voltage of the impulse transformer is adjusted by phase-angle control if the measured values deviate
from the set point. The resulting change in the current through the heatsealing band leads to a change in the band
temperature and thus also its resistance. This change is measured and evaluated by the RESISTRON
®
temper-
ature controller.
The control loop is closed: ACTUAL temperature = SET temperature. Even minute thermal loads on the heat-
sealing band are detected and can be corrected quickly and precisely.
The thermoelectric control loop which is formed has a highly dynamic response because purely electrical variables
are measured at a high sampling rate. A very wide secondary current range can be controlled with only minimal
power loss - a considerable advantage - because power is controlled on the primary side of the transformer. This
allows optimum adaptation to the load and to the required dynamic range despite the exceptionally compact
dimensions of the controller.
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Traits of the controller
• Very simple operation thanks to AUTOCAL, the automatic zero calibration function.
• Good dynamic response of the control system thanks to AUTOTUNE, which adapts automatically to the con-
trolled system.
• High precision thanks to further improved control accuracy and linearization of the heatsealing band character-
istic.
• High flexibility: The AUTORANGE function (as of April 2005) covers a secondary voltage range from 0.4V to
120V and a current range from 30A to 500A.
• Automatic adjustment to the line frequency in the range from 47Hz to 63Hz.
• Increased protection against dangerous conditions, such as overheating of the heatsealing band.
