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Power Supply FAQs

Micron has a team of application experts who have been helping customers with transformer and other electrical power product questions since 1971. Browse our frequently asked questions or contact Micron customer service.

Are external fuses required on the input of Micron DINergy™ power supplies?

Since Micron provides internal fuses on the input of these power supplies, an external fuse is not required. Since the internal fuse is soldered to a PCB and is not field replaceable, an external fuse may be added as it can be replaced easily if necessary.

Switch mode power supplies differ from linear power supplies in how the primary AC voltage is converted into the output DC voltage. Switch mode power supplies use a power transistor to produce a high-frequency voltage that is passed through a small transformer and then filtered to remove both the AC component and noise. Linear power supplies deliver DC by passing the primary AC voltage through a transformer and then filtering it to remove the AC component. Switching power supplies feature higher efficiencies, lighter weight, longer hold-up times, and the ability to handle wider input voltage ranges. Linear power supplies are usually less expensive but are limited in capability and tend to be larger in physical size. Although switch mode power supplies generate high-frequency noise resulting from the use of a power transistor, Micron DINergy™ units employ excellent filtering circuits that reduce the condition to acceptable levels.

Ambient temperature rating refers to the relationship between the label power rating, the application ambient operating temperature, and the actual power capacity after required derating if necessary. Many manufacturers list their power supply ratings based upon a 40⁰C ambient. This means that the nameplate rating (i.e.; 60 watts) only applies if the unit is operated within an environment with ambient temperatures at or below 40⁰C. If the unit is operated above 40⁰C, the unit power capacity must be significantly reduced, with full derating usually occurring at 50⁰C. In this example, a 60-watt 40⁰C design would be revalued at 30 watts in a 45⁰ ambient, and inoperable at 50⁰. However, Micron power supplies are designed and nameplate-rated for operation up through 60⁰C. The Micron design can still operate above the 60⁰C design parameter but must be gradually derated as the ambient approaches 70⁰C. This is important in two respects. First, the specifying engineer must match the ambient operating temperature to an appropriate power supply design to avoid overloading the power supply. Second, the purchaser of the power supply must pay attention to the differences in operating temperature ratings to make an intelligent buy decision, as the performance differences between the 40⁰and 60⁰ designs are significant, hence the lower unit cost for the lesser design.

It is also important to be aware of the difference between “operating range” and “operating power range”. Many manufacturers list the “operating range” for their power supplies as -20 to 70⁰C, even though the 40⁰C design does not provide power above 49⁰C. If there are any questions concerning the suitability of a specific power supply design in regard to anticipated ambient operating temperatures, the user should request a temperature/power curve chart, which should display the point and range of required power derating for the unit.

Micron units may be combined as long as the units are identical in model, the output voltages are matched, and the connecting cables are identical in gauge and length.

Micron units may be paralleled to provide redundant operation, enabling one unit to “stand-in” in the event of a secondary circuit fault on the other connected power supply. As is the case for parallel connections connected to provide increased power capacity, only identical units may be combined, and output voltage settings and load cable gauge and length must match. In addition, the user may elect to connect a diode array at the output terminals of the two units to reduce the likelihood of back-feeding in the event of a unit failure. This can be accomplished by using the Micron DINergy™ MD-PDMA diode module.

Unlike many competitor designs, Micron power supplies feature a “universal autoselect” input design that enables a user to connect input voltages ranging from 100 to 240VAC without selecting a voltage switch position. The Micron DINergy™ unit senses the applied input voltage and automatically configures to safely accept that rating, eliminating the chance of unit damage due to over or under-voltage input connection. Most competitor designs require a manual switch actuation to match the input voltage, making the possibility of failing to set the switch a real potential for equipment damage.

First, power factor correction is required for CE marking as an indication of compliance with EN61000-3-2. Second, the label “power factor correction” is somewhat misleading, as the goal of the standard is to minimize the injection of harmful harmonic “noise” onto the control and power circuits connected to the power supply. To accomplish this, power supply manufacturers include a filtering circuit in the unit design. Some manufacturers employ passive filtering designs which provide minimal reduction of the harmonics. Micron employs an active filtering design which provides superior filtering results.

Class 2 compliance requires a maximum power output availability of less than 100 watts for the component.

Devicenet involves the integration of power and data on a common network conductor. Devicenet requires that the power source be Class 2 compliant.

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