EN - 025930 - How to use +PAR module?

EN - 025930 - How to use +PAR module?

Question

I have a PAR sensor in the greenhouse and the software module +PAR.

How to use the +PAR module?

Answer

The iSii + PAR module is optional from version 3.3.3.1 or higher. With this module you can control the PAR value under the (partly) closed curtain within a certain margin automatically.

Based on the outside radiation or PAR weather, the curtains are already placed in a certain position. This is therefore the pre-control.

The desired PAR value is entered via iSii + PAR setpoint - ViP.



By means of a second ViP setting, the so-called iSii + PAR: influence - ViP 100 = active, 0 = not active, the fine control can be made active or not active.


Release +PAR fine control

As soon as the control is released AND the curtain is closed, the program compares the PAR measurement with the desired PAR value and the difference between the two values is calculated.
This difference is transformed to an influence called iSii + PAR: influence which can vary between 1000 and -1000.
By using this influence in the VIP curtain position, the curtain will be (further) closed when the PAR value is too high. If the current PAR value is lower than the setpoint, the curtain is again (further) opened, just as much until equilibrium is reached. If the conditions change, the PAR regulation responds by sending the curtain open or closed.



The recommended method is with 2 curtain. The bottom curtain has the function of "diffuser", the upper curtain has the function of light supply regulator.
The lower curtain will be closed from a certain radiation level outside or a certain value of the PAR weather. It is of course possible not to close this curtain completely but partially. But usually this is undesirable due to light strips over the crop.
With the upper curtain the light supply can now be controlled with a combination of pre-control based on the outside radiation or PAR weather, and fine control based on PAR crop.

In the above example the curtain is closed b ased on the outside radiation or PAR weather with a certain position of 80%.
With the aid of the iSii + PAR influence, the curtain position can then be corrected to a maximum of +20% to -20% based on measured PAR crop.
The best division between pre-control and fine control may vary per season.



As soon as the setpoint PAR sum is set, a difference PAR sum influence is calculated between the actual 24 hours PAR sum measurement and the setpoint PAR sum. This difference can be used as an influence in, for example, the setpoint PAR to increase or decrease the actual PAR light. By making use of different periods, a difference can be made between morning and afternoon. See the example below.



Do you like to know how to measure PAR light? Read this article: How to measure PAR light

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