Find Class 2 Power Units, 12vdc Desktop, 24vdc Desktop on Industry Directory, Reliable Manufacturer/Supplier/Factory from China.

Inquiry Basket (0)
Home > Industry Information > Electronic Basics: How to Choose and Use a Safe Power Source

Electronic Basics: How to Choose and Use a Safe Power Source

2021-05-02

Today, power users are faced with countless choices. The numerous features of power products and the long product specifications of power suppliers have made buying power a headache. Gratifying now there are a lot of process standard technical specifications that can help engineers buy reliable and safe power supplies.

The safety first power supply equipment needs to provide isolation function, so as to ensure the safety of the power supply equipment from the danger of high-voltage feeders. It is the most basic and often overlooked. This kind of security of power supply equipment is realized by the power transformer, so, in order for the transformer to transmit enough power, it must have a corresponding scale.

A larger transformer is usually equipped with a radiator so that a good product life can be obtained. In addition, double isolation is used between the primary and secondary coils of the transformer to ensure maximum safety.

Reliability People often simply require the life of a power supply product. Actually, there are many factors that affect the life of a power supply, such as average load rate, vibration, and ambient temperature. Among them, the ambient temperature is very important, so the total heat generated by the internal components of the power supply is critical.

Because power supply equipment manufacturers do not understand the end-user's conditions of use, the only life performance they can provide is the power supply product's mean time between failure (MIBF), the MTBF value of the power supply, and in any case, the power supply. The value of the internal electrolytic capacitor MTBF is determined. When the power supply device eliminates the influence of the capacitance, its calculated MTBF may be 100,000 hours or more. However, the typical MTBF value of an electrolytic capacitor is only 30,000 hours.

Since some manufacturers of power supply equipment manufacturers have developed their own power supply MTBF calculation method and the calculated MTBF value is relatively high, it is better for the user to use the MTBF value defined in MIL-HDBK-217E. The value of the power supply MTBF given by the manufacturer is compared to determine the product's performance. Because the calculated MTBF method defined by MIL-HDBK-217E has been proven and widely accepted, the calculated MTBF value is also verifiable.

When evaluating the nominal life of a power supply product, whether the power supply is operating at a rated full load condition is another important consideration in evaluating the power supply. If the power supply unit is fitted with a suitable heat sink and there is no thermal cycling, the power supply can have a longer lifetime if it is operated continuously below the full load. Considering the above factors, it is recommended that the selection engineer should rely on the MIL-HKBK-217E method to verify the value of the MTBF of the power supply product to ensure that the power supply operates under the proper conditions. If this is done, it is no longer necessary to consider the short lifetime of the electrolytic capacitor. problem.

Another key performance factor of a power factor correction power supply is its power factor. The power factor defined in the textbook is the phase angle cosine between the voltage and current waveforms applied to the load (if the phase angle difference between the voltage waveform and the current waveform is φ, cosφ is the power factor of the power supply). When the voltage and current waveforms applied to the load are in the same phase (that is, the phase angle difference φ=0), the power factor cosφφ=1 is ideal; when the voltage and current waveforms applied to the load, the phase angle difference is 90°. When (ie, φ=90°), the power factor is equal to zero (at a minimum value); usually, the power factor of the power supply is between 0 and 1, that is, 0≤cosφ≤1, which can be expressed as a percentage.

One of the consequences of the phase difference between the voltage and current waveforms applied to the load is that the power supply efficiency is reduced, that is, the generation of the required power requires the input of more power; another result and more serious consequence is that That is, the waveform difference between voltage and current generates too many higher harmonics. A large number of high-order harmonics are fed back to the main input line (grid), causing the grid to be contaminated by high-order harmonics as a hidden danger of malignant accidents; at the same time, such high-order harmonics can also disturb sensitive low-voltage circuits in the control system.

There are two main power factor correction (PFC) methods available: the first method uses a simple coil at the input; the second method uses a special electronic power factor correction circuit. Using a coil called "passive" PFC, a power factor of typically 0.7 to 0.8 can be achieved with this method. Using the second method (also called "active" PFC) produces the least amount of higher harmonics to more efficiently use the power provided by the grid. Active PFC can generate a power factor higher than 95%, which is most useful in large power supplies because the generated higher harmonics are directly proportional to the load current. For example, the use of an active PFC method is optimal in a 10V or even higher load current 24Vdc power supply.

Engineers should realize that the importance of having a power factor correction function for the power supply is not only to ensure that the power supply does not radiate or to transmit undesired electrical noise. Therefore, as a planning and selection engineer, it is necessary to find a power supply product conforming to the specifications. These specifications include the electric emission specification EN55011-BtEN55022-B and the specification EN61000.3.2 on pollution emission from higher harmonics.

Surge protection Power surge protection is an increasingly popular feature. Many power supplies have used separate surge protection devices to prevent high voltage peaks, such as lightning strikes.

Some switching power supplies now provide surge protection as defined in EN61000-4-4 and EN61000-4-5, which is a built-in surge protection function (up to 4kV surge protection), since no additional suppressors are required This reduces the precious panel space. This new international standard makes it easy for engineers to select power supplies because the standardization of surge protection has long been established.

Overload and Short-Circuit Protection An important feature of any power supply is its ability to provide continuous full-load capability. What's more important is that the power supply has some built-in margin of error or fault tolerance for calculating (considering) overload conditions. A good power supply can provide a minimum of 5% overload protection. Ideally, it provides 10% overload protection.

The so-called overload condition refers to taking excess current from the power supply, and the planning and engineering engineer has two options. The first option is that the power supply device initiates a hiccup circuit when the power supply is subjected to an overload condition. With this design, the power supply device can be suspended, and after a pause, the power supply attempts to restart and continue working. When the overload condition disappears, the power supply restarts successfully and normal operation resumes. This design is suitable for low current devices.

For larger power supplies, a method called “constant current” power supply is a better choice for overload protection. In this case, when the power supply is always forced to supply a constant current, the power supply device lowers its output voltage.

The short-circuit protection function is another safety feature of the power supply device. This feature cannot be ignored. Although the main purpose is safety, the biggest advantage is that the power supply has an automatic reset feature. The protection provided by this feature lasts until the short-circuit fault has been found.

The economics of power supply and size are related to the economics and geometry of the power supply. Fortunately for the end user, both the economics and geometry of the power supply have improved. Some of the newer power supply products provide the above-mentioned full performance. Compared with the past, it can obtain 50% lower package size than the old low-efficiency design products at a lower cost.

In both economical and geometrical dimensions, it is often more geometrically dimensioned. Because in the past accumulated a large number of geometric techniques, such as the use of smaller components and effective board size. Some of the most effective designs now incorporate heat sinks into the power enclosure enclosure space, thereby effectively reducing the space and cost of additional heat sinks and plastic enclosures.

Easy to use There is an additional common requirement for power supplies that is easy to assemble. Many power supply products today offer a wide variety of design features such as maximum assembly flexibility and lowest final installation and connection costs. To meet worldwide applications, popular power supplies include sensitive and safe DIN-rail-mounting brackets, tiny housing designs, and universal input voltage ranges. Other features of the power supply include the following: Front Panel Mount Input and Output Connections, Plug-In Touch Reliable Termination Blocks, Easy Assembly/Replacement Input Fuses and Output Voltage Adjustments.

Recently, a new type of power supply product has been put on the market. This product is directly connected to the three-phase input voltage of 340 to 480 Vac, eliminating the cost and space required for voltage drop transformers. The end result is that this new power supply product is more efficient and less costly than a single phase power supply additional transformer.

One of the consequences of the phase difference between the voltage and current waveforms applied to the load is that the power supply efficiency is reduced, that is, the generation of the required power requires the input of more power; another result and more serious consequence is that That is, the waveform difference between voltage and current generates too many higher harmonics. A large number of high-order harmonics are fed back to the main input line (grid), causing the grid to be contaminated by high-order harmonics as a hidden danger of malignant accidents; at the same time, such high-order harmonics can also disturb sensitive low-voltage circuits in the control system.

There are two main power factor correction (PFC) methods available: the first method uses a simple coil at the input; the second method uses a special electronic power factor correction circuit. Using a coil called "passive" PFC, a power factor of typically 0.7 to 0.8 can be achieved with this method. Using the second method (also called "active" PFC) produces the least amount of higher harmonics to more efficiently use the power provided by the grid. Active PFC can generate a power factor higher than 95%, which is most useful in large power supplies because the generated higher harmonics are directly proportional to the load current. For example, the use of an active PFC method is optimal in a 10V or even higher load current 24Vdc power supply.

Engineers should realize that the importance of having a power factor correction function for the power supply is not only to ensure that the power supply does not radiate or to transmit undesired electrical noise. Therefore, as a planning and selection engineer, it is necessary to find a power supply product conforming to the specifications. These specifications include the electric emission specification EN55011-BtEN55022-B and the specification EN61000.3.2 on pollution emission from higher harmonics.

Here you can find the related products in Electronic Basics: How to Choose and Use a Safe Power Source, we are professional manufacturer of Din Rail Power Supply,Din Rail Power Supply 24Vdc,12V Din Rail Power Supply,Din Rail Dc Power Supply. We focused on international export product development, production and sales. We have improved quality control processes of Electronic Basics: How to Choose and Use a Safe Power Source to ensure each export qualified product.
If you want to know more about the products in Electronic Basics: How to Choose and Use a Safe Power Source, please click the product details to view parameters, models, pictures, prices and other information about Din Rail Power Supply,Din Rail Power Supply 24Vdc,12V Din Rail Power Supply,Din Rail Dc Power Supply.
Whatever you are a group or individual, we will do our best to provide you with accurate and comprehensive message about Electronic Basics: How to Choose and Use a Safe Power Source!

Din Rail Power Supply, Din Rail Power Supply 24Vdc, 12V Din Rail Power Supply, Din Rail Dc Power Supply
Class 2 Power Units,12vdc DesktopCo., Ltd. http://www.yingjiaoadapters.com