Introduction to Insulating Boards
2026-03-18
Insulating board Also known as insulating rubber mats, insulating pads, insulating shims, and insulating blankets. Insulating mats are widely used in substations, power plants, distribution rooms, laboratories, and on-site live-line operations.
Structure of the insulating plate: The upper and lower surfaces of the insulating plate shall be made of rubber insulating material and shall be free from harmful irregularities. Harmful irregularities of the insulating plate refer to any defects that compromise the uniformity and smooth surface profile, such as pinholes, cracks, localized protrusions, cuts, inclusions of conductive foreign matter, creases, gaps, uneven corrugations, and casting marks. Harmless irregularities, on the other hand, are surface irregularities that arise during the manufacturing process.
Randomly select and measure the thickness at no fewer than five distinct points across the entire insulation board. Measurements may be taken using a micrometer or an instrument of equivalent accuracy. The micrometer must have an accuracy of no more than 0.02 mm; the measuring probe diameter shall be 6 mm, the flat pressure foot diameter shall be (3.17 ± 0.25) mm, and the pressure foot shall be capable of applying a force of (0.83 ± 0.03) N. The insulation pad shall be laid flat to ensure smooth measurement with the micrometer.
Characteristics of insulating boards: excellent physical and mechanical properties, superior insulation performance, operation in dry air over a temperature range of –35°C to +100°C, and stringent requirements for dielectric constant.
Precautions for using insulating boards:
1. Insulating boards exhibit excellent resistance to electric arcs and tracking. Given that these boards are installed outdoors and directly exposed to atmospheric conditions, and in the case of mixed-traffic railway lines also subjected to contamination from oil fumes, water vapor, and coal dust, dust particles readily adhere to the surface, potentially leading to leakage through the insulation layer. When subjected to electric arc exposure, the surface of the insulating board undergoes carbonization, with irregular carbon traces distributed across the surface, thereby compromising its insulating properties. Therefore, stringent manufacturing process requirements must be imposed to ensure a smooth surface that is resistant to soiling and exhibits superior arc resistance. Prior to use, samples of the insulating board shall be tested for tracking resistance and arc resistance.
2. Do not operate it in a surface discharge state to extend its electrical service life.
Insulating plates serve as the insulating medium between the catenary system and the ground. Due to the limited clearance beneath bridges, the contact wire may come into contact with the insulating plate, leading to surface discharge. Epoxy glass-fiber-reinforced plastic exhibits a linear relationship with SMC molding compounds, whereas unsaturated polyester glass-fiber-reinforced plastic shows a piecewise-linear relationship; however, both indicate that the service life of insulating materials is significantly reduced under strong electric fields—particularly under conditions of surface discharge. Therefore, in engineering practice, insulating plates should, whenever possible, avoid operating under conditions that promote surface discharge. The catenary suspension structure should, wherever feasible, adopt an isolated suspension configuration, ensuring an air gap between the contact wire and the insulating plate to provide secondary insulation. Under such conditions, most of the grounding voltage of the catenary is applied across the air gap, resulting in a lower voltage on the insulating plate. Only when a locomotive passes beneath the bridge might the contact wire momentarily make contact with the insulating plate. Consequently, this isolated suspension design can effectively prevent surface discharge and extend the electrical life of the insulating plate.
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Address: No. 1, Xinning West Road, Group 6, Ningtong Residence, Jiang’an Town, Rugao City, Jiangsu Province
Nantong Longyu Rail Equipment Co., Ltd.
Contact: General Manager Wu
Address: No. 1, Xinning West Road, Group 6, Ningtong Residence, Jiang’an Town, Rugao City, Jiangsu Province
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