# Design and Experiment of Dry-Ice Cleaning Mechanical Arm for Insulators in Substation
## 2 General Design of Dry-Ice Cleaning Mechanical Arm System  
Compared with conventional methods, dry-ice cleaning technology is more safe, economical, and nondestructive [35; 36], which can effectively remove the contaminated particles on the surface of metals, insulators, and semiconductors [37]. [PERSON] [38; 39] thinks that the microsolids in high-speed jet can improve the removal efficiency of surface particles. The power frequency voltage and current-leakage test of dry-ice cleaning system shows that dry-ice cleaning has been widely used in on-wire cleaning of transformer, insulator, generator, and steam turbine due to its unique insulation  
Figure 1: Schematic diagram of dry-ice cleaning insulator: (**a**) When dry-ice strikes the polluted layer; (**b**) when the polluted layer breaks; (**c**) when microexplosion air-flow and compressed air-flow remove the pollution. performance [40; 41]. Due to the good insulation performance, cleaning effect, and environmental protection characteristics of dry-ice cleaning, this paper adopts the method of dry-ice cleaning insulator, using high-pressure gas carrying dry-ice particles to impact the insulator surface. When the dry-ice strikes the insulator surface, it will vaporize instantaneously with the change of thermodynamic state, and the heat exchange between the dry-ice particles and the insulator surface will occur rapidly, resulting in the rapid cooling of the surface, and the dirt will be frozen, embrittled, cracked, the bonding force with the cleaned surface will be reduced, and even happens with the \"bone separation\" falling off (the thermal expansion coefficient of two different materials is different). Dry-ice particles (powder) expand nearly 100 times in an instant after getting into the dirt cracks, thus causing multipoint \"micro blasting\" at the impact point and blowing the dirt off. At the same time, with the grinding and impact of dry-ice particles and with the blowing and cutting of compressed air, the dirt is peeled off from the cleaned surface in solid form, thus achieving the purpose of dirt removal, as shown in Figure 1.  
There are at least hundreds of insulators or at most thousands of insulators in different substations, and the aerial high-voltage transmission wires crisscross, the ground high-voltage equipment is complicated, so it is difficult to use helicopters, UAVs, and other air cleaning operations to take aerial cleaning operation. Based on that, this paper proposes a kind of electrified dry-ice cleaning mechanical arm system, which is mainly composed of mobile platform, dry-ice cleaning mechanical arm, dry-ice conveying system, and hand-held controller. The mobile platform is mainly responsible for the movement of the whole system in the substation, carrying the dry-ice cleaning mechanical arm to reach the insulator needed to be cleaned. According to the cleaning task needs and the layout of the equipment in the station, different moving paths can be selected, such as spline 1 or spline 2 in Figure 2. The mechanical arm of dry-ice cleaning system drives the nozzle to move up, down, left, and right to clean the whole insulator at a fixed position, as shown in L01 to L36 in Figure 3. The dry-ice conveying system mainly includes high-pressure gas generation system and dry-ice particle conveyor. Via high-pressure gas, dry-ice particles are carried to impact the surface of insulator needed to be cleaned. The wireless communication mode is adopted between the hand-held controller and the system, which can control all direction movements of the mechanical arm and the operation for dry-ice cleaning circuit. According to the different environment of the substation, the mobile platform can be transformed by using engineering vehicles or tracked robots. This paper focuses on the research of electrified dry-ice cleaning mechanical arm. Figure 2: Insulator cleaning path.