Infrared lamps Medium and Short Waveform
Infrared Short Wave loads can be driven with different types of Firing: Single Cycle, Burst Firing and Phase Angle with Current Limit.
The graph above demonstrates how the inrush current remains high for a longer period if we use Phase Angle plus Current limit, than with Single Cycle. Single Cycle technique is the most used to drive infrared short waveform. During the Off time the IRSW elements become cold (due to their low inertia) and when switched ON again there is a peak of current. This peak of current is a function of the number of Burst Firing Cycles, for this reason the Off time must be as short as possible to reduce this current peak. Phase Angle firing is not used because the supply voltage is normally less than nominal and therefore the elements never reach the working temperature.
CD Automation can provide a complete panel including:
- thyristor unit
- temperature or humidity controller with Auto/Manual command. The temperature can be detected with thermocouple or pyrometer
- an input for speed can be the main setpoint or a trim set of the power
- IR Platens
- Glass Forming
- Oil Industry
- Printed Electronics
There are different types of infrared: short, medium and long waveform.
Let’s see in particular the different kinds of infrared:
- short waveform: peak current ~ 7 times I nominal. Attention must be payed in sizing the thyristors
- ultrashort waveform: peak current ~ 16 times I nominal. Attention must be payed in sizing the thyristors
- medium waveform: I peak equal to I nominal. No attention must be payed to peak current
- fast medium: These elements are in thungsten like short type and the peak current is lower but the necessary time to be heated is longer and this stresses the thyristors
- long: I peak equal to nominal. No attention must be payed in sizing the thyristors
- In car industry and in other special applications the short IRW are supplied with very low voltage compared with the nominal one to change the IRW penetration. Cure must be used for these applications for current sizing of thyristors. In fact, must be used the normal precaution for short waveform plus extra precaution for voltage supply lower than the nominal that causes a lower peak but a very long overcurrent that stresses the thyristors. For sizing contact CD Automation, it will be necessary to collect more informations from the supplier of the IRW short.