EMC detection scheme for uninterruptible power supply equipment

by:Power Kingdom     2021-06-17

Uninterruptible power supply (UPS), as a high-quality power source, is widely used in various industries that require high grid reliability. With the continuous development of industrial power supply technology, higher requirements have been put forward for UPS electromagnetic compatibility performance and its detection technology. This article combines UPS EMC testing related international and domestic standards, systematically introduces UPS electromagnetic interference and electromagnetic susceptibility testing requirements, and provides effective solutions.

Introduction

Uninterruptible power supply equipment (UPS) is a constant frequency, stable voltage, pure, uninterrupted high-quality power supply, With the rapid development of modern information technology, its importance is becoming more and more obvious, especially in industries such as telecommunications, banking, power, transportation, finance, and national defense that require high grid reliability. UPS is a special equipment that is both the load of the power grid and the power supply to the load. Its electromagnetic compatibility must ensure that it does not cause electromagnetic pollution to the power grid, and it must also ensure that it provides a stable and reliable power supply to the load. Therefore, it is very important to comprehensively test and evaluate electromagnetic compatibility characteristics from the perspective of UPS's electromagnetic interference (EMI-Electromagnetic Interference) and electromagnetic susceptibility (EMS-Electromagnetic Susceptibility).

According to the characteristics of UPS products, the electromagnetic compatibility of UPS mainly includes the input and output conduction interference of the power supply, the radiation interference of the power supply and the anti-interference characteristics of the UPS. At present, the special standard required by UPS EMC is GB 7260.2-2009/IEC 62040-2:2005 [1]. In addition, according to the different test items, you need to refer to the corresponding standards. Each standard specifies the harassment emission limit and immunity requirements of various types of electrical and electronic equipment in each frequency band, and clarifies the corresponding test methods and requirements for measuring instruments and equipment.

1. UPS EMC detection program

UPS EMC performance includes EMI and EMS, EMI requires UPS to operate normally The electromagnetic interference to the environment and other things (including equipment and systems) during the process cannot exceed a certain limit; EMS characteristics require the UPS system itself to operate stably under electromagnetic disturbance conditions, such as anti-lightning, static electricity, and ringing waves Ability to wait for interference. For different EMC characteristics, the standard test requirements are different, and a professional test plan must be selected for testing. Refer to Table 1 for specific test items.

2, UPS EMC performance test instructions

The following are just a few examples of UPS typical EMC performance tests.

Radiation disturbance detection

There are transformers, inductors, switching tubes, rectifier tubes and other nonlinear devices in the UPS. The influence of capacitance can easily form a common mode current. A closed current loop will generate a magnetic field, and at the same time it will be accompanied by a radiated electric field. As a source of interference, UPS emits radiation disturbance to the surrounding space during operation. The radiation disturbance in UPS will affect the normal operation of some high-sensitivity electrical appliances in the surrounding area. The radiation disturbance test is used to evaluate the degree of radiation disturbance. According to the requirements of special UPS standards such as GB 7260.2-2009/IEC 62040-2:2005 [1] and basic standards such as GB 4824-2004/CISPR11:2003 [2], it is necessary to measure the electric field radiated by UPS space in the frequency range of 30MHz-1GHz Weight. Figure 1 (left) and Figure 1 (right) are the typical UPS radiation emission measurement principle and the measurement system including the anechoic chamber. Based on the requirements of relevant standards, the frequency measurement range of the system has been expanded to 3GHz to meet the requirements of more High testing requirements.

Power terminal conduction disturbance detection

When UPS is working, in addition to radiating disturbance to the surrounding environment through space, it also generates disturbance to the power grid through the power line. If there is a high-amplitude conduction disturbance at the UPS power terminal, it is very likely that computers and other information technology equipment on the same power grid will be interfered, causing problems such as data loss of the information equipment. Standards such as GB 7260.2-2009/IEC 62040-2:2005 [1] and GB/T6113.201-2008/CISPR 16-2-1:2003 [3] limit the disturbance voltage emitted by UPS along the power line to the power grid. The value and measurement method have made clear requirements. Figure 2 shows the measurement system designed by Hangzhou Yuanfang Company according to the standard requirements. The measurement is carried out in a shielded room. The system is mainly composed of an artificial power supply network and an EMI receiver. The measurement frequency range is 10Hz-30MHz, covering the 150kHz-30MHz required by the standard.

Radiation immunity test

Electromagnetic radiation is ubiquitous, such as radio stations, mobile radio transmitters, various industrial electromagnetic radiation sources, and even fluorescent lamps. Produce electromagnetic radiation. These radiations will have an impact on the working UPS, and in severe cases, it will cause the UPS to malfunction or impair its performance. The electromagnetic field radiation immunity test is used to evaluate the immunity of the equipment under test to the radiated electromagnetic field from space, GB/T 17626.3-2006/IEC61000-4-3:2006 [4] and GB 7260.2-2009/IEC 62040-2 :2005 [1] and other standards specify the minimum immunity requirements, test methods and equipment requirements of UPS to surrounding radiated interference. Figure 3 (left) and Figure 3 (right) are typical radiation immunity measurement principles and test systems, which can fully meet the test requirements of the above-mentioned basic standards and UPS special standards.

Static discharge immunity test

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