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Mountain mine power projects face harsh construction constraints, making traditional split substation installation time-consuming and risky. As professional portable power substation manufacturers, Chuanli integrates all substation components in factory for its mine-specific prefabricated substation and sous-station compacte transformer. This article summarizes on-site deployment difficulties and standardized fast construction processes to offer full construction guidance for mine EPC and engineering teams.
Compared with flat industrial parks and urban construction sites, mountainous mining areas have multiple terrain bottlenecks that restrict the lifting and positioning of portable box transformers. First, the temporary construction pile yard on the slope is narrow and irregular, there is no large flat lifting operation surface, the road slope is large, the large-tonnage crane can only stop at a limited fixed point, the lifting radius is short, and the difficulty of horizontal movement of the whole machine is high; Second, the bearing capacity of the soil foundation of the mountainous area is unstable, and after the heavy-duty box transformer is placed, it is easy to collapse locally and uneven settlement, causing the transformer of the box transformer to tilt and the connection of the busbar to break. Third, the mountain roads have sharp bends and height limits, and the pre-installed complete machine cannot be designed with a large size, which greatly increases the difficulty of balancing control of heavy integrated equipment. At the same time, there is a risk of falling rocks in the mine hoisting operation area, which puts forward higher requirements for the safety protection and rapid positioning efficiency of mobile box transformer hoisting.
The temporary power supply of the mine has strict requirements on the construction period and environmental conditions of the prefabricated substation. The construction plan of the mine is compact, and the substation equipment must be completed within 1-3 days after arrival to complete the power supply. The traditional substation cannot meet the demand for rapid commissioning. The mine site has a lot of dust and slag, and the mechanical equipment continues to vibrate, requiring an integrated sealing and seismic structure. At the same time, the load fluctuation of mine drilling, blasting and excavation operations is very violent, and the transformer of the box-type transformer needs to reserve sufficient overload margin, and the internal modular structure supports the rapid replacement of damaged parts without disconnecting the whole machine. The special mobile unit box transformer for Chuanli mine optimizes the overall lifting balance frame and internal quick assembly module design for the above-mentioned mine-specific needs. The whole lifting, positioning, and wiring process can be completed within 1 working day, and the construction efficiency is much higher than that of split equipment.
| Comparative dimensions | Split assembled substation | Chuanli mining mobile box transformer |
| Weight of hoisting unit | Transformer, cabinet and frame are hoisted separately and in batches | The whole machine is hoisted in one go |
| Mountain yard area requirements | Large area of parts required to be stacked on flat ground | Only a small flat foundation of 6m×8m is sufficient |
| Total on-site installation period | 3–5 working days | Hoisting in place completed within 8 hours |
| Earthquake-resistant structure | Split parts are loose and wiring is easy to loosen | Factory integrated fixed modular frame |
| Lifting safety hazards | Multiple liftings increase the probability of collision | One hoisting reduces the number of high-altitude operations |
The four corners of the whole machine frame of the mobile pre-assembled container are equipped with integrated lifting ears, which do not need to be temporarily tied with a sling on the site, and prevent uneven loading forces from causing deformation of the cabinet.
The completion of the pre-inspection of the whole machine, the hoisting tools, and the preparation of the site before the equipment arrives at the mountainous site is the core prerequisite for realizing rapid hoisting and integrated installation, which can avoid repeated waiting and rework in the middle of the hoisting operation, and the whole text is fluent and fragmented.
Two rounds of full inspection of internal substation components were carried out before the mobile box substation was shipped out of the factory and after it was delivered to the mountain site of the mine. The initial inspection at the factory focuses on verifying the tightness of the integrated framework, the torque of the bolts on the base of the transformer, the tightness of the oil seal of the transformer in the box-type transformer, the locking of the high and low-voltage cabinet locks, the complete bundling of the internal prefabricated busbars, and ensuring that there are no loose parts during long-distance mountain transportation. After the equipment arrives at the mine yard, the receiving team visually inspects the outer wall of the cabinet for any signs of collision deformation, paint loss, or oil leakage, opens the inspection door to check if the shock-absorbing pads of each module have shifted, and verifies the completeness of the random-supplied lifting equipment, grounding copper bar, and complete set of fast-wiring terminal accessories. If there are broken or loose components, they should be re-tightened and replaced before hoisting to avoid delaying the project due to faults after installation.
| Verification module | Core inspection items | Qualification criteria |
| Complete machine frame | Four-corner integrated lifting lugs, integral welding | No cracks and deformation, and the lifting lugs are intact and intact |
| Box-type transformer | Oil tank seal, bottom shock-absorbing pad | No oil leakage, shock-absorbing pad fixed without displacement |
| High and low voltage cabinet modules | Cabinet door locks, internal prefabricated busbars | All terminals have torque standards |
| Auxiliary accessories | Quick connector, grounding assembly | Complete supporting accessories without missing parts |
| Cabinet outer wall | Anti-collision coating, drainage structure | No impact damage, smooth drainage channel |
In response to the narrow lifting space and complex terrain in mountainous areas, special lifting equipment should be equipped in advance according to the weight of the mobile prefabricated substation. Taking the standard 1250 kVA mobile unit box transformer (total weight 12.8 tons) of Chuanli as an example, a short-arm 25-ton hydraulic crane is selected to match the limited lifting radius of the mountain, and four equal-length high-strength steel wire ropes and a special balanced lifting beam are provided to ensure four-point uniform loading. Safety protection materials include mountain anti-falling safety belts, rock fall protection panels, warning isolation fences, and dust-proof goggles for operators; Auxiliary tools include a torque wrench, a leveling jack, a foundation foot bolt tightening kit, and a quick wire stripper. All hoisting equipment must pass the flat load test before entering the mountain, so as to eliminate the hidden dangers such as the breaking of the sling and the failure of the hydraulic system of the crane when hoisting on a steep slope.
The four corners of the top of the whole frame of the mobile box transformer of Chuanli Mine are prefabricated symmetrical and integrated lifting ears, which are the only designated lifting bearing points. The lifting rope must not be tied to the transformer tank, the cabinet wall, and the bottom steel location to prevent the local deformation and cracking of the transformer tank of the box transformer.When lifting, the balanced lifting beam is hung on the crane hook, and the four lifting ropes are connected to the four corner lifting ears. Adjust the length of the lifting rope to control the overall horizontal inclination within 3°, and the angle between the single lifting rope and the vertical direction does not exceed 60°, so as to avoid the cabinet frame from being subjected to excessive horizontal pulling force.Before the formal lifting, a 0.5-meter trial lift was carried out, and the frame deformation, sling slippage, and transformer offset were checked for 5 minutes. After confirming that there were no abnormalities, a slow horizontal movement was carried out.
The three-step operation principle of “slow lift, slow move, slow fall” should be followed for the hoisting and positioning of the narrow pile yard in the mountainous area. After the test lift is qualified, the crane slowly lifts the entire machine to a height higher than the height of the foundation fence, and the ground command personnel guide it horizontally to the side of the pre-leveled concrete foundation; Special personnel are arranged to observe the slope of the mountain above the working area during the translocation process to prevent falling rocks. The whole box transformer is suspended at 200 mm from the base surface, aligned with the bottom foot bolt hole and the foundation pre-embedded components, and then slowly lowered.After positioning, use four hydraulic jacks to adjust the overall horizontal error to within ± 2 mm / m, use a torque wrench to lock all foundation bolts according to the manufacturer’s standard torque, and complete the entire lifting and positioning process within 40 minutes under standard conditions.
After the mobile unit box substation is smoothly placed on the foundation, the modular integrated assembly and rapid wiring operation can be carried out, without the need for separate transportation and separate assembly of each substation component, greatly compressing the on-site construction cycle, and the logical continuity of the section is seamless.
Chuanli Mine Box Transformer Factory adopts a fully modular layout, with medium-voltage cabinets, transformer compartments, and low-voltage distribution compartments separated by fast locking connectors, eliminating the need for extensive on-site welding and busbar assembly. After the lifting and positioning is completed, the construction personnel only need to open the inspection door on each compartment side, check the plug-in joint of the prefabricated busbar between modules, and manually lock the locking bolt of the slightly loose joint. The auxiliary control module and energy storage backup module are specially designed for the mining machine, and the signal circuit is assembled using prefabricated quick plug connectors. The entire internal module assembly can be completed within 1 hour without disassembling the cabinet frame.
The high-voltage input line, low-voltage output line, and ground main line of the prefabricated substation are all reserved with standard fast connection terminals at the bottom of the cabinet, which saves the process of cutting and crimping the cable head on-site.The first step is to lay the grounding main copper bar, connect the four grounding reserved points at the bottom of the box with the mine’s total grounding network, and test the grounding resistance ≤4Ω;The second step is to connect the high-voltage overhead cable to the medium-voltage in-line prefabricated cable head, and lock and seal the pressure cover; The third step is to distribute the load cable of each mining machine to the low-voltage output quick terminal, and the torque wrench is tightened according to the standard torque of the terminal. The fourth step is to connect the secondary monitoring signal cable to the reserved intelligent communication terminal, and complete the signal debugging. The whole wiring process of a single mobile box transformer can be completed in 2 hours under the condition that the cable is complete.
Combining with the many years of experience in supplying power to mountainous mines, it summarizes five core efficient construction techniques, further compressing the whole lifting and installation period of the mobile box transformer. Three days before the first equipment enters the mountain, the concrete foundation pouring, leveling treatment and bearing capacity test should be completed in advance to avoid waiting for the foundation to solidify after the box transformer arrives. The second requirement is that the manufacturer should accompany the complete machine with a balanced crane beam, a set of lifting ropes, and quick wiring auxiliary tools, to prevent delays in construction caused by the temporary purchase of tools in the mountains; The third crane and professional lifting personnel entered the site 1 day in advance to clean the lifting pile yard, adjusted the location of the crane according to the slope terrain, and the box transformer transport vehicle could be lifted directly when it arrived; The fourth is to use the integrated prefabricated structure of the special mine equipment of Chuanli, which eliminates the separate lifting of transformers and switchgear cabinets, and reduces the number of high-altitude and high-risk operations. All substation components are fully simulated and debugged before leaving the factory, and only simple unloaded tests are carried out after on-site wiring, which saves the complex debugging process of the whole machine.
Q1: What kind of special lifting structure is used in the mobile box transformer of Chuanli Mine?
A1 : The four corners of the whole machine frame are prefabricated symmetrically integrated hangers, and a special balanced hanger is provided to achieve four-point balanced lifting.
Q2: How long does it take to complete the whole lifting of the standard 1250 kVA portable box transformer after it arrives at the yard?
A2 : The entire lifting and positioning operation under standard terrain conditions should be completed within 40 minutes.
Q3: What is the standard for the horizontal flatness of the mobile unit box after landing on the mountain base?
A3 : The overall horizontal error of the jack is controlled within ±2mm/M.
Q4: Why can the prefabricated substation of Chuanli achieve quick assembly of internal modules?
A4 : Factory pre-installed prefabricated busbar and locking connection board, no busbar welding required on site.
Q5: What is the grounding resistance required after the connection of the mine box transformer?
A5 : The grounding resistance test of the whole machine shall not be higher than 4Ω, meeting the requirements of mine safety regulations.
Constrained by complex terrain, mountain mine substation construction suffers low efficiency and high risks. Chuanli’s integrated Sous-station compacte, unit substation and prefabricated electrical substation adopt modular design and professional hoisting structure. It greatly shortens on-site construction cycle, eliminates equipment damage risks, and serves as the optimal solution for rapid power delivery of mountain mine temporary power projects.
