A high-pressure discharge lamp (HPS lamp, from the English High-Pressure Sodium lamp) is a type of gas discharge lamp that operates by creating an electric arc between two electrodes in a high-pressure gas mixture. These lamps are widely used for outdoor lighting , industrial lighting , and plant lighting (such as in greenhouses and grow tents).
Characteristics of a high pressure discharge lamp (HPS):
-
Light color : HPS lamps emit a yellow-orange light , which has a fairly warm and diffused effect. This makes them ideal for street lighting, but also for flowering and fruiting plants, as the light falls primarily in the red spectrum.
-
Energy efficiency : HPS lamps are relatively energy-efficient compared to older technologies like incandescent bulbs. They provide a lot of light for the amount of energy they consume.
-
Long lifespan : HPS lamps generally last longer than incandescent bulbs , for example. Their lifespan can vary from 12,000 to 24,000 hours , depending on the type and conditions.
-
High light output : HPS lamps offer a high light intensity and are therefore often used for applications where a lot of light is required.
-
Different Wattages : HPS lamps are available in a wide range of wattages, from 35 watts to 1000 watts or more, depending on the application.
Applications of high pressure discharge lamps:
- Street Lighting and Outdoor Lighting : HPS lamps are widely used for public lighting, such as streetlights and parking lots, because of their high light output and energy efficiency.
- Plant Lighting (Grow Lights) : In the plant growing industry, HPS lights are widely used for the flowering and fruiting stages of plants because the light is mainly red , which promotes flowering.
- Industrial Lighting : They are often used in warehouses, factories and other industrial environments where bright, long-lasting light is required.
Advantages of HPS lamps:
- High efficiency : They produce a lot of light per watt of energy.
- Longer life : HPS lamps often last longer than incandescent and energy-saving lamps.
- Suitable for outdoor environments : HPS lamps are highly resistant to weather conditions, making them suitable for outdoor use.
Disadvantages of HPS lamps:
- Color rendering : The color spectrum of HPS lamps isn't ideal for fully reproducing colors, as they emit primarily reddish light . This makes them less suitable for applications where true color rendering is important (such as in art galleries or shops).
- Warm-up Time : HPS lamps have a warm-up time , meaning they take a while to reach full brightness after being turned on.
- High heat production : HPS lamps produce quite a bit of heat , which can be a problem in some environments, especially when used in closed or poorly ventilated spaces.
How does a high pressure discharge lamp (HPS) work?
- Gas discharge : The lamp contains a gas mixture, often consisting of sodium and mercury . When an electric current flows through the gas mixture, it creates an arc discharge , which emits light.
- High Pressure : The lamp operates at high pressure , which means the gas molecules are closer together, contributing to the intensity of the light.
- Electronic Ballasts : Because HPS lamps require a higher starting voltage , they are often powered by a ballast that supplies the correct voltage and current.
Applications for plants:
- Plant cultivation : HPS lamps are particularly suitable for the flowering and fruiting phase of plants, because the red light in the spectrum stimulates flowering.
- Hydroponics : HPS lights can be used in hydroponic systems to promote plant growth without soil.