Posted on: July 1, 2014

What is Operating Range?

The operating range is the minimum and maximum input voltage limits within which a power supply will operate to specifications. A power supply with a wide input range is recommended when the line voltage is subject to brownouts and surges.

The operating range of a power supply may also refer to other parameters other than voltage. Manufacturers often specify the recommended operating conditions in which their products will conform to the output specs. The main parameters that operating range may refer to include:

  • Input voltage
  • Temperature
  • Frequency
  • Humidity

The manufactures usually specify both an upper and lower limit of the said parameters, of which a component or circuit such as the power supply will operate efficiently or deliver its rated output.

The operating frequency range refers to the interval between the upper and lower frequency limits, in which the power supply will operate normally. Operating the supply outside these limits will most likely lead to malfunction or errors in the powered equipment.

The operating range is based on the components that make the power supply, reliability of the power supply, and field of application. This differs from one application to the other. For example, a power supply for consumer equipment for home and office may have narrower operating ranges compared to military, marine or medical equipment.

The power supplies with wider ranges or those that can tolerate wide variations of the operating conditions are usually constructed with more robust components and tend to be more expensive.

The equipment with a wide operating range such as the input voltage means that it can work in many places, from a variety of unstable power sources without affecting its output or blowing out the power supply components.

Typical operating ranges for power supplies

Temperature range: Most components have different temperature grades based on application and environment where they will be used. The most commonly grades are commercial, industrial and military.

Standard temperature range:

  • Commercial equipment from 0°C to 70°C
  • Industrial equipment from -40° to 85°C
  • Military equipment from -55° to 125°C

However, most manufactures may design their equipment with a wider operating range compared to the standard, meaning that their equipment is able to withstand harsher conditions.

As such it is common to find a commercial supply with a temperature range of between: 0°C to 85°C and an industrial one with Industrial: −40°C to 100°C.

These will usually be specified at a certain humidity range typically between 0 to 95% humidity. In addition, manufacturers can specify the temperatures at half load, full load and in storage.

Other operating range values include:

Input voltage range: Some power supplies have an auto range feature such that it can work at 115V or 230V. Others have manual switch to select the input voltage.

In most cases the operating range will depend on the supply voltage and there are two sets of the range:

  • 85 to 135 V AC for 115 volts supply
  • 170 to 270 V AC for the 230 volts supply

Frequency range: Most supplies operate are designed to operate at either 50Hz or 60Hz. The operating range is usually 48-62Hz, meaning that either of the supplies will work on the other frequency.

Equipment or power supplies with a wide range of operating temperature can work in many areas and best suited for military applications due to their mobility and may find themselves in extremely cold or hot environments. Using equipment outside the recommended range is not advisable since it can lead to power supply or equipment damage in addition to posing a safety hazard such as fire to the user or consumer.