Introduction to the test of ringing wave, damped oscillation and damped oscillation magnetic field_Century Wisdom (Suzhou) Testing Technology Co., Ltd

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Introduction to the test of ringing wave, damped oscillation and damped oscillation magnetic field

Release time:

2022-10-31 00:00

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　　Ringing waves are non-repetitive damped oscillatory transients induced into low-voltage cables due to switching of electrical networks and reactive loads, as well as power circuit faults and insulation breakdowns or lightning strikes. Ringing waves are repetitive transients that occur on high or medium voltage power, control, and signal lines. The damped oscillatory wave and the magnetic field coil cooperate to be the damped oscillatory magnetic field test.

　　The test objects of ringing wave, damped oscillation, and damped oscillation magnetic field are all substation equipment or equipment connected to the AC power grid.

　　1 Waveform introduction

　　The rise time T1 of the ring wave waveform is 0.5 μs (open circuit voltage) and ≦ 1 μs (short circuit current), and the oscillation frequency T is generally 100kHz. The peak voltage Pk1 is typically 0.25kV to 4.0kV.

　　Ring wave waveform

　　Damped oscillatory waves are a group of repetitive ringing waves, which can be divided into slow damped oscillatory waves and fast damped oscillatory waves according to their oscillation frequency.

　　The rise time T1 of the first wave of the slow damped oscillation wave is 75ns, the oscillation frequency T is generally 100kHz and 1MHz, and the peak voltage Pk1 is usually 0.25kV to 2.5kV.

　　Slow Damped Oscillatory Waveform

　　The rise time T1 of the first wave of the fast damped oscillation wave is 5ns, the oscillation frequency T is generally 3MHz, 10MHz and 30MHz, and the peak voltage Pk1 is usually 0.25kV to 4.0kV.

　　Fast Damped Oscillatory Waveform

　　The damped oscillating magnetic field uses slow damped oscillating waves.

　　2 Ring wave immunity

　　2.1 Ring wave immunity test requirements

　　The test ports of the ringing wave are EUT power ports and signal ports.

　　The phenomenon of the EUT test has a lot to do with the release phase angle during the ringing wave test, so the ringing wave test at the power port needs to be tested at different phase angles. And the test voltage requirements start from the low level to the target level.

　　The test flow chart is as follows:

　　The power port coupling modes are as follows:

　　Line®GND (source impedance 12W / 30W)

　　Neutral®GND (source impedance 12W / 30W)

　　Line®Neutral (source impedance 12W / 30W)

　　Note: When the EUT port is connected to the main board, the source impedance is 12Ω; when the EUT port is connected to the power outlet, the source impedance is 30Ω.

　　Schematic diagram of single-phase power coupling mode:

　　Schematic diagram of three-phase power coupling mode:

　　Schematic diagram of signal port coupling mode:

　　2.2 Ring wave immunity test arrangement

　　A typical test arrangement for a ring wave test is as follows:

　　When performing the test, the signal generator, coupling/decoupling network, EUT and auxiliary equipment shall be connected to the reference ground plane (GRP), or grounded in other appropriate ways.

　　Except for the reference ground plane (GRP) below, the distance between the equipment under test and other conductive structures shall be at least 0.5m.

　　The coupling/decoupling network shall be connected to the EUT with a 1m long cable.

　　The communication line (data line) should use the cable required by the technical specification, and it needs to be 0.1m higher than the reference ground plane (GRP), and its length should be at least 1m.

　　3 Damped oscillatory wave immunity

　　3.1 Experimental requirements for damped oscillatory wave immunity

　　The ports to be tested in the damped oscillatory wave test are EUT power ports and signal ports.

　　According to the frequency of oscillation, damped oscillation can be divided into:

　　——Slow damped oscillation, the oscillation frequency f is 100 kHz, 1MHz.

　　——Fast damped oscillation, the oscillation frequency f is 3 MHz, 10MHz, 30MHz.

　　1) Slow damped oscillation

　　The setup requirements for the slow damped oscillation test are as follows:

　　Test voltage V peak: 250 V – 2500 V

　　Duration td: not less than 2s

　　Test time T: The standard is not defined, usually 1 minute

　　Interval time tr: standard undefined

　　Repetition rate Rep: 40/s ( 100 kHz) 400/s ( 1 MHz )

　　First Half Cycle Polarity: Positive and Negative

　　Coupling method: differential mode LN; common mode L-PE, N-PE, L+N-PE

　　The schematic diagram of the test waveform is as follows:

　　The test coupling mode is as follows:

　　a) Single-phase power coupling mode

　　Test setup for Line to ground test

　　Test setup for Line to Line test

　　b) Schematic diagram of three-phase power coupling mode:

　　c) Signal port coupling mode

　　2) Fast damped oscillation

　　The setting requirements for the fast damped oscillation test are as follows:

　　Test voltage V peak: 250 V – 4000 V

　　Duration td: 50 ms (3 MHz), 15 ms (10 MHz), 5 ms (30 MHz)

　　Test time T: The standard is not defined, usually 1 minute

　　Interval time tr: standard undefined

　　Repetition rate Rep: 5000/s ( 3MHz, 10 MHz, 30 MHz)

　　First Half Cycle Polarity: Positive and Negative

　　Coupling method: common mode Lx-PE, N-PE, Lx+N-PE

　　The schematic diagram of the test waveform is as follows:

　　The power port coupling modes are as follows:

　　Signal ports are typically coupled using capacitive coupling clamps, the same as the IEC 61000-4-4 Electrical Fast Transient Burst Communication Port Test.

　　3.2 Arrangement of damped oscillatory wave immunity test

　　A typical test arrangement for a damped oscillatory wave test is as follows:

　　Example of a test setup for benchtop equipment using a ground reference plane

　　Example of a test arrangement for floor-standing equipment using a ground reference plane

　　When performing the test, the signal generator, coupling/decoupling network, EUT and auxiliary equipment shall be connected to the reference ground plane (GRP), or grounded in other appropriate ways.

　　Table-top equipment, EUT and cables shall be placed on insulating supports with a height of 10 cm thick, isolated from the GRP.

　　For vertical equipment, the EUT shall be placed on a 10 cm thick insulating support.

　　Except for the reference ground plane (GRP) below, the distance between the equipment under test and other conductive structures shall be at least 0.5m.

　　The coupling/decoupling network is connected to the circuit at a distance of 1m from the EUT and connected to the GRP.

　　If the coupling/decoupling network and the test signal generator are separated, they should be placed close to each other and connected by a wire not exceeding 1m in length. The coupling/decoupling network connection to the GRP should be as short as possible.

　　If the power cord provided by the EUT exceeds 1m, the extra-long cable part should be folded into a flat coil with a diameter of 0.2m and placed 0.1m above the GRP.

　　4 Damped Oscillating Magnetic Field Immunity

　　4.1 Requirements for damped oscillation magnetic field immunity test

　　The damped oscillatory magnetic field uses slow damped oscillatory waves with oscillation frequencies of 100kHz and 1MHz.

　　The setup requirements for the damped oscillating magnetic field test are as follows:

　　Magnetic field strength H: 10A/m – 100A/m

　　Duration td: not less than 2s

　　Test time T: the standard is not defined, usually 10s

　　Interval time tr: standard undefined

　　Repetition rate Rep: 40/s ( 100 kHz) 400/s ( 1 MHz )

　　First Half Cycle Polarity: Positive and Negative

　　The induction coil shall be of sufficient size to enclose the EUT (in 3 mutually perpendicular orientations).

　　4.2 Layout of damped oscillating magnetic field test

　　A typical test arrangement for a damped oscillating magnetic field test is as follows:

　　The EUT should be placed on the GRP with 0.1m thick insulation (such as dry wood blocks) between the two.

　　Cables provided or recommended by the EUT manufacturer should be used. If not recommended, an unshielded cable suitable for the signal involved shall be used and all cables shall have a length of 1 m exposed to the magnetic field.

　　The communication line (data line) shall be connected to the EUT using the cable specified in the technical specification or standard. Each wire near the EUT should be kept at a distance of about 0.1m from the GRP.

　　The test generator should be placed not more than 3m away from the induction coil.

　　The induction coil shall surround the EUT placed at its centre.

　　The induction coil used in the vertical position (horizontal polarization field) can be directly connected to the GRP (at the root of a vertical conductor), and the GRP becomes a part of the coil as the bottom edge. At this time, the shortest distance from the EUT to the GRP is 0.1m is enough.

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