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Power supplies are under mounting pressure to perform in a growing market — one forecast to increase steadily, reaching a value of $14.23 billion in 2028. Power supply manufacturers must keep providing consumers with form factor, power density and cost innovations to stay relevant. Many power supplies must perform in less-than-ideal environments while still meeting high power specifications.
Derating information is available in the product's datasheet and must be carefully considered when choosing a power supply for various applications.
What Does Power Derating Mean?
Derating means operating a system below its headline to meet safety, thermal and reliability requirements. In power supplies, the output current is often derated for specific input voltage and thermal conditions to ensure it operates safely and reliably. Low input voltages can place excessive stress on a power supply due to increased input current. Temperature requires careful thermal management for all components. Thermal limits are placed on components and systems to avoid changes in component behavior or complete component failure.
In essence, derating is a protection technique to prevent catastrophic failure and increase component longevity. It increases the margin of safety between part design limits and applied stresses, reducing the degradation rate. Several environmental conditions can increase a power supply's temperature, including ambient temperature, installation altitude and mounting orientations. As power supplies do not regulate derating automatically, you must adapt the device to your application's ambient conditions during installation.
Understanding power derating and specifications is essential for selecting the correct power supply. Checking derating specifications is critical in power supply design for the following reasons:
- Current and voltage limits: Derating specifications may include voltage and current limits under diverse conditions. Accessing this information is critical when selecting power supplies to prevent overload and ensure components operate within a safe and productive range.
- Temperature considerations: As electrical components often have reduced efficiency or capability at higher temperatures, understanding derating specifications can ensure a power supply can handle the intended use and operate within safe thermal limits.
- Altitude and environmental factors: Aerospace and industrial applications must carefully consider environmental conditions. Derating specifications account for these factors, allowing you to select a power supply that performs reliably in various conditions.
- Longevity and reliability: Derating information provides insights into a power supply's expected useful life and reliability. It prevents operation at maximum rated capacity for extended periods, ensuring a power supply can handle a load while maintaining efficiency, reliability and longevity.
Exploring Power Ratings and Derating Curves
Derating specifications involves reducing the specified output power rating during challenging conditions, such as high temperatures and low line input voltage operations. Many power supplies and other electrical components have a derating table. This structured document provides guidelines on their power handling capacity and when they should be derated under different operating conditions.
Consulting a derating table helps engineers determine the appropriate power rating reduction to operate a power supply correctly under environmental conditions. Users generally configure the power supply's desired output voltage and output current limit, controlling the maximum amount of current drawn from it.
Understanding Power Ratings
A power rating defines the amount of electrical energy transferred to a device. It also highlights the maximum power value the appliance can safely operate. The formula for calculating power rating includes:
P = IV or
- P: Power in watts
- I: Current in amperes
- V: Potential difference in volts
Understanding Derating Curves and Their Application in Design and Manufacturing
The derating of a power supply is expressed in derating curves. A power supply has three primary specifications — maximum output voltage, maximum output current and maximum output power, measured in volts, amperes and watts, respectively. Users often configure the output voltage and the output current limit on a power supply to control the maximum amount of current drawn from the power supply.
If users can vary voltage and current, they can produce the same amount of power in various ways. As voltage and current have multiple configured values, the data is represented graphically in a derating curve. This curve provides a graphic representation of the voltage and current combinations a power supply can support. A power supply supports any combination of voltage or current that falls on or below the derating curve.
All derating curves have a maximum power output curve. This curve outlines all the voltage and current combinations that yield maximum power from the power supply.
Calculating Power Derating for Optimal Performance
Derating curves are often supplied for power supplies, informing users of safe thermal operating conditions. Understanding these curves helps you choose the most appropriate power supply for your application. Power supplies have several sensitive components under significant thermal stress— the high operating frequencies and currents will cause the temperature of these components to rise. Standard derating graphs simplify the process of calculating safe temperature variations.
When selecting a power supply, several variables can influence or be influenced by derating. Consider the following factors to understand derating power supply applications better:
Ambient Temperatures
Industrial power supplies almost always require derating above a specific ambient temperature to protect sensitive electronics. Users must reduce the output power linearly above a defined temperature limit, using the datasheet to locate the corresponding values. Consider these values when selecting a power supply to establish whether a device requires derating at lower temperatures.
Many power supplies require derating from relatively low temperatures. Your chosen power supply should have a higher temperature limit before it requires derating. You can also select a unit with a higher output to ensure you have sufficient power available before derating.
Altitude
As altitudes increase, atmospheric pressure and air density decrease, reducing airflow's cooling effects. Power supplies also require derating for installations above 2,000 meters, making them essential for many aerospace and defense applications. The specified values for reducing output power after 2,000 meters vary depending on the type of power supply unit. Integrating a cooling system is another way to maintain maximum output safely.
Mounting Orientation
How you mount your power supply impacts derating requirements. If the mounting orientation affects the power supply's airflow, it may not cool the interior components as efficiently. Standard installation orientations allow hot air to exit the power supply from the top, and temperature-sensitive components are placed in the coolest areas of the power supply.
If your power supply's orientation deviates from the recommended standard installation, it could impact airflow. Derating prevents these components from overheating, maintaining the power supply's longevity and reliability.
The Importance of Power Supply Derating in Product Applications
Many industries require a careful balance of performance and safety in power supplies, and derating power supplies can provide that balance in multiple industries and product applications, including:
- Aerospace: Derating allows power supplies to operate reliably in high-altitude environments despite air pressure and temperature variations.
- Medical devices: Medical devices require high power stability and reliability. Derating helps maintain consistent performance in environments with fluctuating temperatures and humidity levels, boosting patient safety.
- Industrial: Machinery must often operate in challenging industrial settings, including vibrations, dust and temperature variations. Derating power supplies is essential to reduce downtime and prevent equipment damage.
- Telecommunications: Telecommunications equipment must often operate in environments with limited airflow or high ambient temperatures. Derating power supplies in these settings decreases the overheating and component failure risk.
Power Derating With Astrodyne TDI
Power derating is critical when choosing power supplies for various industries and applications to ensure safe operation while achieving maximum outputs. Trust the professionals to walk you through power derating requirements for your industry and save yourself significant time and money in the long term.
Astrodyne TDI has been committed to meeting our client's unique power supply needs for decades as an industry-leading power provider. Our custom power supply solutions can meet the challenges of various environments, meeting your derating and output requirements, no matter the application. Let us worry about the power, so you don't have to. Reach out to us today, and our skilled and experienced team will help you find the ideal power supply.
