Emi Filter for Dc Power Supply

1. Customized Design, Precisely Matching Needs
The VIIP IEC socket filter adopts a customized design concept, fully considering the working environment and special requirements of indoor and outdoor displays. Whether it’s an indoor high-definition display or an outdoor large advertising screen, there is a perfectly matched filter model available. This design not only maximizes filtering effectiveness but also effectively extends the lifespan of the display and reduces maintenance costs.

2. Excellent Filtering Performance, Ensuring Pure Signals
As a professional power filter, the VIIP IEC socket filter excels in filtering performance. It can effectively filter out high-frequency noise and electromagnetic interference from the power line, providing a stable and pure power environment for displays. This pure power signal is key to ensuring accurate colors and clear images on the display, forming the foundation for an ultimate visual experience.

3. Safe and Stable, Protecting Every Visual Enjoyment
Safety and stability are another highlight of the VIIP IEC socket filter. The product is made from high-quality materials and undergoes strict quality control and safety testing to ensure stable performance even in harsh working environments. Additionally, its unique protective design effectively prevents issues such as overcurrent and overvoltage, providing comprehensive protection for displays and allowing users to enjoy visual feasts without worrying about safety concerns.

4. Environmentally Friendly and Energy-Saving, A New Choice for Green Living
In today’s society, environmental protection and energy conservation have become focal points of attention. The VIIP IEC socket filter takes this into account during its design, optimizing circuit design and material selection to achieve low energy consumption and high efficiency. This not only reduces energy waste but also lowers operational costs for users, delivering tangible economic benefits. Furthermore, it aligns with the modern society's green living philosophy, making it a new choice for users pursuing a high-quality lifestyle.

Certifications and Market BenefitsWith our support, the client successfully achieved UL certification and EMC compliance—marking a vital step toward expanded global market access. These certifications validate the product’s safety, reliability, and electromagnetic compatibility, reinforcing the manufacturer’s industry reputation and customer confidence.Our Commitment to Customer SuccessWe pride ourselves on delivering tailored testing solutions aligned with international standards, empowering our clients to meet regulatory requirements efficiently. Our team’s deep technical expertise and proactive approach ensure that product development cycles are shortened, costs are controlled, and compliance is achieved with confidence.As industry leaders in EMC testing support, we remain dedicated to helping manufacturers like yours excel in global markets by providing expert guidance, advanced testing services, and strategic solutions.ConclusionAchieving EMC compliance is a complex but critical process. With our comprehensive testing services and technical support, your products can successfully meet international standards—accelerating your journey toward global certification and market success.

So, how can the performance of power filters be tested?


Leakage Current

Leakage current refers to the current flowing between the phase line, neutral line, and the filter casing (ground line) under a voltage of 250VAC. It primarily depends on the value of the ground capacitor (common mode capacitor). A larger common mode capacitor CY can improve insertion loss but may result in higher leakage current.


Withstand Voltage

To ensure the performance of the power filter, as well as the safety of equipment and personnel, withstand voltage testing must be conducted. Withstand voltage testing is performed under extreme operating conditions. If the withstand voltage performance of the CX capacitor is poor, it may break down when peak surge voltage occurs. While its breakdown may not endanger personal safety, it can cause the filter to lose functionality or performance.


Performance Evaluation

When using EMI power filters, the most important considerations are the rated voltage and current values, withstand voltage performance, and leakage current. The primary performance evaluation of a filter is its insertion loss performance.

The ability of an EMI power filter to suppress interference noise is measured using Insertion Loss (I.L.). Insertion loss is defined as the ratio of the power P1 transmitted from the noise source to the load without the filter connected to the power P2 transmitted from the noise source to the load with the filter connected, expressed in decibels (dB).


Standard Insertion Loss Testing
Load Insertion Loss Testing
Time Domain Testing for EMI Filters


Design of an Automatic Insertion Loss Testing System for EMI Filters

As EMC testing becomes more complex and the workload increases, the requirements for testing equipment in terms of functionality, performance, testing speed, and accuracy are also rising. Traditional manual testing is increasingly unable to meet these requirements. National standards (GB) and national military standards (GJB) both require EMC testing to be automated, with strict requirements for data post-processing. Therefore, the development of EMC automatic testing has become essential. The automatic testing system established in this article utilizes virtual instrument technology and is based on a signal source and spectrum analyzer to test the insertion loss of EMI power filters.

Power filters are essential components in electronic devices, with the main function of filtering the input power signal to remove noise and other interference, providing a stable and smooth direct current or alternating current voltage to ensure the normal operation of electronic devices. Power filters are widely used in electronic products, especially in high-end electronic products that require signal stability, reliability, and safety.

In addition to the main functions and roles mentioned above, power filters can also serve the following purposes:


Filter out high-frequency noise in the input power, reduce interference to the system, and minimize electromagnetic radiation.
Prevent transient changes in the power supply circuit to avoid impacting the system.
Avoid sudden surges in the power line to enhance system reliability and stability.

So, how can the performance of power filters be tested?


Leakage Current

Leakage current refers to the current flowing between the phase line, neutral line, and the filter casing (ground line) under a voltage of 250VAC. It primarily depends on the value of the ground capacitor (common mode capacitor). A larger common mode capacitor CY can improve insertion loss but may result in higher leakage current.


Withstand Voltage

To ensure the performance of the power filter, as well as the safety of equipment and personnel, withstand voltage testing must be conducted. Withstand voltage testing is performed under extreme operating conditions. If the withstand voltage performance of the CX capacitor is poor, it may break down when peak surge voltage occurs. While its breakdown may not endanger personal safety, it can cause the filter to lose functionality or performance.


Performance Evaluation

When using EMI power filters, the most important considerations are the rated voltage and current values, withstand voltage performance, and leakage current. The primary performance evaluation of a filter is its insertion loss performance.

The ability of an EMI power filter to suppress interference noise is measured using Insertion Loss (I.L.). Insertion loss is defined as the ratio of the power P1 transmitted from the noise source to the load without the filter connected to the power P2 transmitted from the noise source to the load with the filter connected, expressed in decibels (dB).


Standard Insertion Loss Testing
Load Insertion Loss Testing
Time Domain Testing for EMI Filters


Design of an Automatic Insertion Loss Testing System for EMI Filters

As EMC testing becomes more complex and the workload increases, the requirements for testing equipment in terms of functionality, performance, testing speed, and accuracy are also rising. Traditional manual testing is increasingly unable to meet these requirements. National standards (GB) and national military standards (GJB) both require EMC testing to be automated, with strict requirements for data post-processing. Therefore, the development of EMC automatic testing has become essential. The automatic testing system established in this article utilizes virtual instrument technology and is based on a signal source and spectrum analyzer to test the insertion loss of EMI power filters.

At VIIP Filter, we recently had the opportunity to assist a customer with their vending machine project, helping them to achieve UL certification. This case study showcases our efforts in providing EMI power filters and technical expertise to overcome EMC issues and successfully pass laboratory testing.

Project Description:

The vending machine initially faced challenges in passing UL certification due to electromagnetic compatibility (EMC) issues. Our engineering team intervened by implementing various solutions to address the problem and ensure compliance with industry standards.

First Attempt: Installing VIIP Filter EMI Power Filters

In the first attempt to mitigate the EMC issues, we installed four of our 20A single-phase filters in the vending machine. Despite this intervention, the certification was still not achieved, prompting us to explore additional solutions.

Second Attempt: Adding Ferrite Core Rings

To further improve EMC performance, our engineer onsite added two ferrite core rings (magnetic toroids) to the vending machine. While this adjustment helped reduce margin issues, there was still a small residual offset that needed to be addressed.

Upgraded Filters and Ferrite Rings

Following the feedback from the laboratory testing, our engineering team decided to upgrade the previous single-phase filters and reintroduce the ferrite rings. With these improvements in place, the vending machine underwent EMC tests once again, and this time, it successfully passed the certification requirements.

The Role of VIIP Filter EMI Power Filters:

VIIP Filter's EMI power filters played a crucial role in improving the vending machine's EMC performance. By providing reliable filtering solutions, we helped our customer enhance the machine's electromagnetic compatibility, ensuring compliance with UL certification standards.

Technical Expertise and Onsite Support:

In addition to supplying EMI power filters, our engineering team offered valuable technical expertise and onsite support throughout the certification process. By closely collaborating with the customer and addressing specific EMC challenges, we were able to identify the root cause of the issue and implement effective solutions.

The successful outcome of this project highlights VIIP Filter's commitment to quality, innovation, and customer satisfaction. By leveraging our EMI power filters and technical knowledge, we were able to assist our customer in overcoming EMC issues and achieving UL certification for their vending machine. This case study exemplifies our dedication to providing reliable filtering solutions and personalized support to meet our clients' unique requirements.