Power Supplies
Power supplies are used to deliver a consistent voltage and current. Testing and research requires clean power of a specific value, facilitating a process with repeatable results. Power supplies are available in many formats, providing different types and levels of electricity.
Power Type
In choosing a power supply, the first major decision concerns what type of power you will need. The options are as follows:
- AC only
- DC only
- AC and DC together
Each supply possesses a unique set of characteristics, specific to the type of power it delivers. For example, AC supplies have the option of varying frequency, enabling users to simulate power consumption in various parts of the world, as well as in aircraft and submarines.
Number of Channels, Power Capacity, Interfaces
Power supplies are available in both single and multi-channel formats, with many levels of output capacity. After deciding what type of power is required, you would need to determine:
- How many channels do I need?
- What voltage do I need to supply?
- What current do I need to supply?
- What types of interfaces do I need?
Not all power supplies are the same. While there are smaller units designed for basic home use, there are also extremely complex, high output devices for use in research and development. Power supplies are as varied as test and measurement itself, therefore, it is important to consider exactly what this would be used for. There are also a variety of available interfaces, for connection to computers and other pieces of testing equipment. Connectivity options include USB, LAN, GPIB and RS-232.
Linear vs Switching
Linear and switching power supplies utilize two common methods for varying output voltage and current.
Linear power supplies utilize an internal transformer to change output, creating a smooth transition from one level to the next. Switching power supplies use integrated circuits which are much smaller, and more efficient. However, there is a tradeoff. As switching power supplies step up or down in output, noise can be generated which may be detectable in your measurements. Linear units do not have this problem, but are physically larger, weigh more, and are less efficient.
Programming Ability
Many digital power supplies can be programmed. These units contain internal memory enabling users to quickly recall settings from previous sessions. This shortens the testing process and reduces the chance of human error.