Abstract
Power equipment operates under high voltages, inducing space charge accumulation on the surface of key insulating structures, which increases the risk of discharge/breakdown and the possibility of maintenance workers experiencing electric shock accidents. Hence, a visualized non-equipment space charge detection method is of great demand in the power industry. Typical electrochromic phenomenon is based on redox of the material, triggered by a voltage smaller than 5 V with a continuous current in μA~mA level, which is not applicable to high electric fields above 106 V/m with pA~nA operation current in power equipment. Until now, no naked-eye observation technique has been realized for space charge detection to ensure the operation of power systems as well as the safety of maintenance workers. In this work, a viologen/poly(vinylidene fluoride-co-hexafluoropropylene)(P(VDF–HFP)) composite is investigated from gel to insulating bulk configurations to achieve high-voltage electrical-insulating electrochromism. The results show that viologen/P(VDF–HFP) composite bulk can withstand high electric fields at the 107 V/m level, and its electrochromism is triggered by space charges. This electrochromism phenomenon can be visually extended by increasing viologen content towards 5 wt.% and shows a positive response to voltage amplitude and application duration. As viologen/P(VDF–HFP) composite bulk exhibits a typical electrical insulating performance, it could be attached to the surface of insulating structures or clamped between metal and insulating materials as a space charge accumulation indicator in high-voltage power equipment.
Highlights
Power equipment is the key factor for the safe and reliable operation of power systems [1,2,3]
Polymers are the basic electrical insulating material applied in power equipment, and include: polyethylene (PE), which serves as the core material of power cables; polypropylene (PP), which serves as as the basic energy storage material in power capacitors; and epoxy resin (EP), which serves as the insulating support in gas-insulated switchgears (GIS) [11,12,13]
The electrochromism of a viologen/P(VDF–HFP) composite is investigated from gel to bulk structure for developing electrical insulating electrochromism material
Summary
Power equipment is the key factor for the safe and reliable operation of power systems [1,2,3]. To solve the problem of regional power shortages, large-area ultra-high-voltage (UHV) power transmission is applied, in which power equipment operates under longterm extreme voltages [4,5,6]. A common problem is that, under high voltages, space charges are formed through thermal emission and the tunneling effect, which accumulate on the surface of and inside the insulating polymer. These excessive space charges cannot dissipate as the high voltage is continuously stressed, and may form a local charge concentration, which generates a strong distorted electric field, leading to partial discharge, and even breakdown [14,15,16,17]. Discovering the accumulation of space charges at an early stage is vital for ensuring the stable operation of power equipment [18]
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