PTFE, PFA, FEP, PVDF Fluoroplastic products industry experts
Breakdown characteristics of polytetrafluoroethylene film under nanosecond pulse
Classification:
Industry dynamics
Author:
PFA tube little sister
Source:
Dankai
Release time:
2022-12-21
Visits:
PTFE film is widely used in the field of insulation due to its excellent dielectric, mechanical and thermal properties, and its application in direct, power frequency AC and lightning impulse pulse regular
The breakdown characteristics have been studied in depth. With the development of pulsed power technology, the breakdown characteristics of nanosecond pulses have been widely studied by researchers at home and abroad.
Note. In recent years, single high-voltage nanosecond pulse and low repetition rate pulse power supply are more common, so the current nanosecond pulse of PTFE film breakdown characteristics of the main focus.
in a single nanosecond pulse.
The breakdown of the gas gap under the repetition frequency condition is different from that under a single pulse. The breakdown does not occur when the first pulse is applied, but after several, dozens or more pulses
After that, the breakdown needs to withstand a certain repetition frequency tolerance time. At present, there are few experimental data on the insulation characteristics of PTFE film under the action of repetition frequency fast pulse.
With the innovation of switching devices, the repetition frequency nanosecond pulse power supply of kHz magnitude has gradually appeared, which is very important for exploring the breakdown characteristics of high repetition frequency nanosecond pulse PTFE film.
possible.
The electrical power supply of the experimental device is SPG2000N by a repetitive frequency nanosecond pulse power supply with an output voltage range of 0 ~ 300kV, with a pulse rise time of about 15ns and a pulse width of 30 ~ 40ns,
The repetition frequency is 1~1000Hz, and the average output power is 13kW. The on, off and repetition frequency are controlled by the trigger pulse controller.
Figure 1: PTFE film Source: Dan Kai
In the experiment, after the breakdown of the PTFE film sample, the shutdown of the SPG2000N is realized by turning off the protection circuit to output the shutdown signal to the trigger pulse controller. WR204Xi
Digital storage oscilloscope (bandwidth 2GHz, sampling rate 10GS/s) is used to record the breakdown voltage and current waveform. TDS220 Oscilloscope (Bandwidth 100MHz, Sample Rate
1GS/s) is used to measure the repetition rate tolerance time. Two 10cm long double-layer coaxial cables connect the oscilloscope and the computer for storing data. Laboratory trigger pulse control
oscilloscope, shutdown protection circuit and computer are placed in the shielded room. In the experiment, the hemispherical (R10)-plate electrode system was used for measurement, and the PTFE film was soaked.
in transformer oil.
The breakdown voltage was measured by a coupled capacitive divider attached to the output of the SPG2000N, with a divider ratio of about 10000. Breakdown current measured by self-integrating Rogowell coil
The ratio is about 35mV/A. In addition to automatically shutting down the power supply after breakdown, the shutdown protection circuit will also be used to measure the repetition frequency tolerance time of PTFE PTFE.
The measurement principle is as follows: When the trigger pulse controller outputs a pulse start SPG2000N, channel 1 of the TDS220 oscilloscope starts to record the output pulse at the same time.
When a series of pulses are applied to PTFE to cause breakdown, the breakdown voltage and current signals trigger the WR204Xi oscilloscope to generate a pulse width of 20ms trigger feedback signal.
No., recorded by channel 2 of the TDS220 Expo. at this time, the time difference between the two channel signals of the TDS220 oscilloscope is the measured repetition frequency tolerance time, and the measurement system is guided from the emission
It takes 22 μs to generate a feedback signal from the breakdown pulse control signal to the oscilloscope.
Through the experimental study of the breakdown characteristics of PTFE film under repetitive frequency nanosecond pulses, the parameters such as voltage, current and repetition frequency tolerance time were measured and calculated,
The results show that the breakdown field strength of the PTFE film under the repetition rate nanosecond pulse is of the order of MV/cm. The repetition frequency tolerance time is on the order of ms, indicating that in addition to the intrinsic and electronic
In addition to the collapse breakdown mode, the heat accumulation effect under the repetition frequency nanosecond pulse is also an important breakdown mode, and the defects of the material itself will also promote the thin PTFE.
Membrane breakdown process.
The effects of repetition frequency and applied field strength on the repetition frequency tolerance time and the number of applied pulses were studied, and the results showed that the repetition frequency tolerance time varied with the applied field strength and repetition frequency.
The number of applied pulses decreases nonlinearly with the increase of applied field strength, but increases first and then tends to saturate or decrease with the increase of repetition frequency. in addition,
The nature of the PTFE film itself and the oil immersion time make the experimental data disperse.
This article is originally created by Teflon's little sister. Welcome to pay attention and take you to grow knowledge together!
Key words:
PTFE, film, time, oscilloscope, tolerance, dispersion
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