Power transformers are big, heavy, and surprisingly fragile, especially when fully dressed.
They’re often installed in power substations or other locations that are difficult to access. In a substation, for example, transformers often sit within a complex web of high-voltage wires and electrical equipment, usually with tight clearances throughout. There’s rarely overhead access without moving wiring out of the way.
The costs incurred by a broken transformer are usually high. Downtime at a power station can cost a million dollars a day or more.
For all these reasons, when a transformer needs to be moved, it’s critical to do so quickly, reliably, and safely.
This page explains your options for moving a large transformer, including the benefits and drawbacks of each method:
- Crane Lifts
- Rollers, Skates, and Other Horizontal Methods
- Hydraulic Skidding
Option 1: Crane Lifts
Cranes are the first option most companies think of when they need to move something heavy. They are powerful and well understood. But using a crane to move a transformer comes with challenges.
At power stations, many transformers have lines or infrastructure hanging overhead. To use a crane, these obstructions must be removed. This often means that the station needs to be de-energized, expanding and often extending the power outage.
Power stations are often crammed with tightly placed equipment, meaning there is little clearance surrounding a transformer.
That makes cranes a challenge, as they are sensitive to both wind and weather risk. Power stations in remote locations are also difficult to access for crane systems.
There is also the challenge of moving the transformer itself using a crane.
Lifting a fully-dressed unit by crane means suspending a sensitive, oil-filled piece of equipment in the air. The bushings and external components must be stripped before attempting this kind of move, adding time and labor to the initial move and reassembly.
Option 2: Rollers, Skates, and Other Horizontal Methods
The difficulty of cranes at power stations often leads crews to attempt moving a transformer with steel rollers, skates, winch lines, or a combination of the three.
The benefit of these systems is that they do not require removal of overhead obstructions. They are also far less sensitive to wind and weather than using a crane.
With that said, roller systems work by reducing friction, making them a risky choice for sensitive electrical equipment. Once a heavy transformer is moving on rollers or skates, there is very little stopping it if something goes wrong.
Large equipment can easily drift off course, pick up speed on a slight grade, or become unbalanced on uneven ground.
Option 3: Hydraulic Skidding
Hydraulic skidding is not as well known as cranes or roller methods, but it is extremely effective for moving large, sensitive equipment in locations with tight clearance.
Instead of lifting the transformer or using rollers or skates, a skidding system keeps the load supported on engineered tracks while hydraulic cylinders move it forward in short, controlled strokes.
To move a transformer, operators use hydraulic jacks to raise the load a few inches, then install skid tracks underneath. The transformer is then lowered onto skid shoes that ride along the track.
A hydraulic cylinder moves the load forward one push at a time until the transformer reaches its final position.
The load never moves faster than the hydraulic system allows. There is no momentum to manage and no risk of a runaway load. When pressure is released, movement stops right away. If something unexpected happens, the system stalls rather than swinging or surging forward as with other methods.
This protects operators, the transformer, and surrounding equipment.
Moving a Transformer: Crane Lifts vs. Rollers vs. Hydraulic Skidding
Here’s a comparison of the three methods for moving a transformer:
9 Questions to Ask Before Moving a Transformer
Each transformer move is different.
Before moving, there are a few questions to answer to help you choose the right method for your situation.
1. How heavy is the transformer?
Start by estimating the total weight of the load you need to move.
A fully-dressed transformer including all its oil, bushings, radiators, and external components can weigh hundreds of tons. The heavier the load, the fewer methods are available to move it safely.
2. Is the location accessible or remote?
Moving a transformer at a substation near a highway is very different from moving one at a hydroelectric facility in the mountains. Remote locations make it more difficult and more expensive to use large equipment such as cranes. Remote locations also limit your options if something goes wrong.
3. Are there overhead wires or obstructions?
Transformers at power substations usually have a variety of obstructions overhead, including dangerous, high-voltage wires that are not easily moved.
If you plan to lift the transformer with a crane, some or all of the overhead obstacles will need to be removed, adding time and cost to the effort.
By contrast, movement methods such as hydraulic skidding avoid this issue entirely by keeping the transformer close to the ground.
4. What’s the clearance around the transformer?
Transformers often sit on pads surrounded by other equipment, usually with a narrow corridor for access. In many locations, operators trying to move a transformer must do so with inches of clearance to work with.
If you have only a small amount of room to work with, you’ll need a method that can work within the available clearance.
5. What is the downtime cost?
Downtime can be a major cost at large power stations, sometimes exceeding $1M or more for each day a station is offline.
If operators must spend a day moving overhead obstructions or bringing in cranes and other equipment, the overall cost can rise quickly. Every day of prep work or reassembly after the move adds to the bill.
6. How fragile is the transformer?
A fully-dressed transformer is filled with oil and covered with delicate components like high-voltage bushings and radiator assemblies. These parts cannot handle excessive force, sudden jolts, or changes in tilt.
When moving a transformer with a crane, these delicate components often need to be removed in order to lift the transformer from its location, adding time and cost.
By contrast, methods that keep the load close to the ground can often move the transformer even while fully-dressed.
7. What human resources are available?
When downtime matters, crane lifts require highly-trained operators with years of experience. Not every site or crew has access to that expertise.
Hydraulic skidding systems are much simpler to use. Operators can be trained in as little as a day.
8. What tools and equipment are available?
Some power stations have heavy equipment on site. In other locations, you may need to bring in equipment, which adds costs and potential downtime to the project.
9. What’s the total cost of each of your options?
The cost of moving a transformer goes well beyond the movement method itself. Total cost includes many of the issues we’ve just discussed:
- Getting equipment to and from the site
- Preparation of the site, including removing and rebuilding infrastructure around the transformer
- Crew time
- Downtime
In the case of a transformer at a power station, the total time to get the station back online is often the key differentiator in the overall cost.
Why Hydraulic Skidding Is a Common Option for Transformer Moves
Transformer moves are one of the most common use cases for hydraulic skidding systems worldwide. When using skidding, there is:
- No need to remove overhead lines or infrastructure
- Much lower dependence on good weather conditions
- Low risk of catastrophic failure or damage to surrounding equipment
- Distance between the operators and the load, which is controlled safely through hydraulic lines
Operators can learn how to run a hydraulic skidding system in a day rather than the years it takes to develop skills as a crane operator.
For power utilities that regularly replace transformers, some choose to buy a skidding system and keep it available on site. If the system saves even one or two days of downtime during a swap, it will more than pay for itself.
Choosing the Right Method for Your Transformer Move
Each transformer move is unique, which means there is no method that is the best method for every situation.
The key factors are:
- Transformer weight
- Whether it will be fully-dressed or stripped down
- Overhead obstacles
- Clearance
- Site access
- Downtime cost
- Acceptable risk
For many transformer moves, hydraulic skidding offers a combination of safety, precision, and efficiency that is difficult to match with other methods.
If you often move transformers as part of your operations, our team at Hydra-Slide can help you understand if hydraulic skidding is an option for your needs.
