Closed Loop Control; Temperature Measurement (Thermocouples); Power Control Methods; Zero Cross Control - Husky Altanium Neo2 User Manual

2.1.2 Closed Loop Control

With the aid of a thermocouple, it is possible to control the actual temperature inside the
mold. The Altanium controller can only control the temperature at the point at which the
temperature sensor is positioned. The position of the thermocouple, combined with the
capacity (wattage) of the heaters, in relation to the application, will be the over-riding factors
in the response of the system. The control parameters have been matched to this response
for optimum control. This method of control is referred to as Automatic Regulation.
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2.1.2.1 Temperature Measurement (thermocouples)

To control the temperature within a closed loop system, the Altanium controller must be
able to measure the process temperature. This is achieved using a thermocouple.
There are various types of thermocouples, but in the plastics industry they are predominantly
of the Iron/Constantan type, generally known as Fe/Cu-Ni, Iron/Con or type "J"
thermocouple. The other type used to a lesser extent is Nickel-Chromium/Nickel-Aluminum,
Ni-Cr/Ni-Al, or type "K".
These thermocouple types are physically recognizable by a combination of their individual
core and sheath colors; however, these vary from standard to standard.
2.2

Power Control Methods

In an effort to match the energy input requirements of differing types of loads, it is necessary
for the output power delivered to the heaters to be adjusted over a range of 0 to 100%. The
Altanium controller can be set up to achieve this by using either Zero Cross Control or Phase
Angle Control.

2.2.1 Zero Cross Control

This method defines how the power to each heater is averaged over a period of time. This is
achieved by switching complete half cycles of the heater supply voltage using an Alternistor
Triac as a switching device.

2.2.2 Phase Angle Control

This method defines how the power to each heater is adjusted, by varying the point in each
half cycle at which the Alternistor Triac (switching device) is turned on.
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Internal thermocouples are normally associated with larger part weight tips, bodies, and
runners. These tend to have relatively fast responses due to the fact that the
thermocouple is in close proximity to the heater.
External thermocouples are normally associated with manifolds. These tend to have
relatively slow responses due to the fact that the thermocouple is separated from the
heater by a mass of metal.
Altanium Neo2
Closed Loop Control