SPD
SPD turns up in 3 fields: electrotechnology, lighting, shop slang. Here is what it means to the people in each one.
SPD in electrotechnology
A surge protective device used to limit transient overvoltages and divert surge currents.
An SPD (surge protective device) is a component installed in electrical panels to protect downstream equipment from voltage spikes caused by lightning or grid switching. It works by presenting a high impedance at normal operating voltages and rapidly dropping to a low impedance when a high voltage transient occurs. This shunts the destructive surge current safely to earth before it damages sensitive electronics.
"We need to install a Type 2 SPD at the main distribution board to protect the new server racks."
SPD in lighting
Spectral Power Distribution: a graph of how much power a light source emits at each wavelength.
Spectral Power Distribution, the radiant power of a source plotted against wavelength, usually from 380 to 780 nm. It is the fundamental description of a light source: CCT, CRI, TM-30, melanopic values and lumens are all calculated from it. A typical white LED shows a sharp blue peak near 450 nm from the chip and a broad phosphor hump through green, yellow and red; incandescent is a smooth rising curve.
"Send me the SPD, not just the CRI, I want to see how deep that red end goes before we approve it for the museum."
SPD in shop slang
The sterile processing department is the central facility in a hospital where medical instruments are cleaned.
Sterile Processing Department. The centralized area in a healthcare facility responsible for cleaning, decontaminating, sterilizing, and distributing medical instruments and equipment. Workers in this area ensure that surgical tools are safe for reuse, operating heavy autoclaves and chemical wash stations.
"Send these trays down to SPD immediately so they can get them turned around for the afternoon surgeries."