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Typical lighting loads have a number of principal characteristics:
- Inrush: Most discharge lighting loads require Power Factor Correction (PFC). The most common method of providing this is by the use of PFC capacitors. When connected to the supply it is possible for hundreds of amps to momentarily flow
The magnitude and duration of the inrush current depends on the value of capacitance (measured in m F) and the impedance of the supply network. This current is capable of welding together contacts of relays and other switching devices. It is also possible for these currents to fuse semiconductors and it is reliant on good product design to ensure that the effect of inrush has been taken into account
- PF (Power Factor): Power factor can dramatically change the characteristics of a load. While a load may be 100W and draw about 0.4A at unity power factor, it will draw over 1A with a power factor below 0.35 (common for discharge loads with failed PFCs)
Some common lamp or ballast faults can also give rise to a situation where only the PFC is connected. In this case although no power is consumed the current through the PECU (Photocell) will also be above 1A. Hence the PECU must be capable of operating the load over the range of likely load conditions, including common failure modes of lantern control gear
- Ratings: It is important to ensure that the maximum ratings are not exceeded, care must be taken to observe both the current rating and the maximum capacitive load that can be connected
Also see
To find out more about the Zodion Lighting Controls range of Photo Electric Control Units, please browse our catalogue pages.
Our PECUs range includes:
If you have any questions, please contact us on 01422 317 317 or fill in our contact form we will be delighted to answer any questions you might have on PECUs.
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