What is a Water-Cooled Cable?

A water-cooled cable is a device that cools the cable by circulating water. It is mainly used for cooling high-power equipment. A water-cooled cable contains an inner conductor and an outer insulation layer, and water flows through the water pipes in it for cooling.

Use of water-cooled cables

Water-cooled cables are mainly used for high-power electrical equipment, such as equipment with high-power motors or inverters, common electric arc furnaces, and welding machines. They are also used in petrochemical, metallurgical, pharmaceutical, and other high-temperature industries. EAF/SAF Water-cooled cables can protect equipment from damage under high loads and extreme working conditions.

Water-cooled cable standards

Many standards apply to the design and installation of water-cooled cables at home and abroad. These standards are formulated to ensure water-cooled cables' safety, reliability, and stability.

International standards

The International Organization for Standardization (ISO) has introduced a series of standards applicable to water-cooled cables. For example, ISO 21678:2018 "Liquid-cooled Cable Systems" provides a detailed specification to guide the design, installation and operation of water-cooled cables. The standard covers many aspects, including transmission parameters, structure of water-cooled cables, design and definition of waterways, etc.

In addition, there are other international organizations that provide standards for water-cooled cables, such as the European Organization for Standardization (CENELEC), the American National Standards Institute (ANSI), and the International Electrotechnical Commission (IEC).

Domestic standards

The China Organization for Standardization (GB/T) also has specifications for water-cooled cables in standards such as "Power Cables" or "Cables for Power Supply and Utilization Equipment". For example, GB/T 5584 "Copper Core Butter Paper Insulated Power Cables" and GB/T 7673 "Cross-linked Polyethylene Insulated Power Cables and Accessories". These standards ensure that water-cooled cables in China meet international standards and are scientific, reasonable, and operational.

The significance of water-cooled cable standards

Water-cooled cable standards help ensure the quality and standards of the design, production, testing, transportation, and installation of water-cooled cables. First-class water-cooled cables should meet the standards and be able to fully serve the needs of users. Formal standard organizations can guide water-cooled cable manufacturers to develop more advanced and efficient products.

How is Water-Cooled Cable Works？

An electrical conductor (like copper) has resistance. When a massive current (thousands to tens of thousands of amperes) flows through it, it generates a colossal amount of heat due to Joule heating (I²R loss). Standard air-cooled cables would melt or catch fire at such loads. The solution: Actively and continuously remove the heat as fast as it's generated. Water is 4,000 times more effective at removing heat than air, making it the perfect cooling medium.

1. Structure: It’s a Hybrid

A typical water-cooled cable (the most common flexible type) is a hybrid of an electrical conductor and a cooling pipe.

•Conductor: Thousands of fine, bare copper strands braided or twisted together. This makes the cable extremely flexible.

•Water Jacket/Cooling Channel: The copper strands are contained inside a sealed, flexible, insulated hose (often made of EPDM rubber or similar). This hose forms the water channel.

•Water Terminals: At each end are specially designed cable terminals (flanges). They have two critical functions:

•Electrical Connection: A solid copper plate or ring to bolt the cable to the power source (e.g., transformer) and the load (e.g., furnace electrode).

•Hydraulic Connection: Inlet and outlet ports to connect to the external cooling water system. Inside, a seal ensures water flows over the copper strands but never leaks into the electrical connection area.

2. How It Works: The Cooling Cycle

Imagine a closed-loop system:

1. Current Entry: Massive electric current enters the cable through the end terminal and flows through the copper strands.

2. Heat Generation: The electrical resistance of the copper instantly converts a portion of the electrical energy into thermal energy (heat). The conductor’s temperature starts to rise rapidly.

3. Active Heat Exchange: Simultaneously, pressurized, cool water (e.g., 30°C / 86°F) is pumped into the cable’s inlet. This water flows directly over and between the thousands of copper strands, making intimate contact.

•Heat from the hot copper conductor is conducted into the cooler water.

•The now-heated water is carried away by the flow.

4.Heat Removal: The warm water (e.g., 45°C / 113°F) exits the cable through the outlet and travels to an external cooling system. This is typically a heat exchanger (like a radiator or cooling tower) that dumps the heat into the atmosphere or a plant cooling circuit.

5.Closed Loop: The now-cooled water is pumped back into the cable inlet, and the cycle repeats continuously.

In essence: The heat is "washed away" by the flowing water before it can accumulate and damage the cable.

3. Why Use This Complex System? The Benefits

•Extreme Current Density: It can carry 10-20 times more current than an air-cooled cable of the same cross-sectional area. This saves massive amounts of expensive copper and allows for more compact designs.

•Controlled Temperature: Keeps the conductor at a safe, low operating temperature (typically 40-60°C), preventing insulation failure, oxidation, and thermal fatigue.

•Enables Modern Industry: Makes processes like electric arc furnace (EAF) steelmaking possible. EAFs draw over 50,000 amperes, and the cables connecting to the moving electrodes mustbe flexible.

•Efficiency & Longevity: By managing heat, it reduces energy losses and significantly extends the cable’s service life.

4. The Supporting System: Not Just a Cable

A water-cooled cable is the central component of a larger system:

•Pumps: To maintain constant water flow.

•Cooling Unit/Heat Exchanger: To remove heat from the circulating water (e.g., cooling tower, chiller, dry cooler).

•Deionization System: Often uses deionized water to prevent mineral scaling inside the cable and, crucially, to keep the water’s electrical conductivity very low. This prevents the cooling water itself from becoming a stray electrical path.

•Filters, Flow & Temperature Sensors: For system monitoring and protection (e.g., to shut down power if water flow stops).

 A water-cooled cable works by turning an electrical conductor into a heat exchanger. It uses continuously flowing water to actively and efficiently remove the immense waste heat generated by ultra-high currents, allowing it to perform tasks impossible for any standard cable.

What are the Types of Water-Cooled Cables?

Water-cooled cables are specialized components designed to carry extremely high currents by actively removing heat. They are primarily categorized by their conductor design and application flexibility. Here’s a clear breakdown of the main types.

Classification By Conductor & Hose Structure (Most Common Classification)

A. Flexible Hose Cable (The Most Common Type)

This is the classic "water-cooled cable" used where movement is required.

•Structure: Thousands of fine, bare copper strands are bundled or braided into a flexible conductor, which is then enclosed inside a seamless, heavy-duty rubber or plastic hose. Water flows directly over the strands.

•Key Feature: High flexibility. It can be bent and moved repeatedly.

•Typical Use: Electric Arc Furnace (EAF) and Ladle Furnace electrode arms, where the cable must move with the oscillating or raising/lowering electrode.

•Visual: Looks like a large, sturdy hose with copper lugs on the ends.

B. Tubular Busbar / Rigid Water-Cooled Cable

Used for fixed, high-current busbar runs.

•Structure: The conductor itself is a solid copper or aluminum pipe. Cooling water flows through the hollow center of the pipe. Often used in pairs (for supply and return) with insulating supports.

•Key Feature: High current capacity, rigid structure, lower impedance. More efficient for high-frequency applications due to better use of the skin effect.

•Typical Use: Fixed installations in electrolysis plants (e.g., aluminum smelting), large DC power supplies, and particle accelerator magnet circuits.

•Visual: Looks like a plumber's copper pipe run, with electrical insulators.

C. Water-Cooled Braid / Flexible Busbar

A hybrid between a hose cable and a solid busbar.

•Structure: Multiple flat, thin copper strips (laminations) are stacked and sometimes braided for flexibility. A water channel is integrated, either as a central hose between the strips or by making the strips themselves hollow.

•Key Feature: Good balance of flexibility and high current capacity in a flat profile. Lower inductance than round hose cables.

•Typical Use: Connections in high-power induction furnaces, large welders, and semiconductor manufacturing equipment where a low-profile, flexible connection is needed.

D. Coaxial Water-Cooled Cable

For applications requiring controlled impedance and minimal external magnetic fields.

•Structure: Consists of a central conductor (cooled pipe), an insulating dielectric, and an outer concentric conductor (also cooled). Water flows in the annulus between them or through both conductors.

•Key Feature: Very low inductance, minimal external magnetic radiation. Provides excellent shielding.

•Typical Use: High-frequency (RF) plasma generators, broadcasting transmitters, and specialized research equipment.

Classification By Cooling Circuit Design

How to Choose the Right Tpes of Water-Cooled Cables?

Choosing the right type depends on:

1. Current & Voltage: Required amperage (AC/DC) and operating voltage.

2.Flexibility Requirement: Does the connection need to move (EAF) or is it fixed?

3.Frequency (AC only): High frequency increases "skin effect," favoring tubular or laminated designs.

4.Space Constraints: Braided or tubular designs offer different form factors.

5.Cooling System: Available water pressure, flow rate, and quality (deionized water is almost always required to prevent short circuits and scaling).

Quick Comparison Table of the water-cooled cables：

The Flexible Hose Cable is the workhorse for heavy industry with moving parts, while Tubular Busbars handle the highest currents in fixed installations. The other types address specific needs like form factor, inductance, or high frequency.

The Advantages and Disadvantages of Water-Cooled Cables

Advantages of water-cooled cables

• Efficient cooling: Water as a cooling medium has high heat capacity and thermal conductivity, and can take away a lot of heat in a short time.

• Stability: The cooling system of water-cooled cables runs smoothly, and the flow, pressure, and temperature of water can be controlled to ensure the stable operation of the equipment.

• Environmental protection: Compared with other cooling methods, water-cooled cables have less environmental impact • Space saving: The design of water-cooled cables requires a smaller volume than airflow cooling, thus saving space.

Disadvantages of water-cooled cables

• Difficulty in maintenance: Water-cooled cables need to be equipped with water cooling systems, pipes, cooling towers, and other accessories, and the maintenance difficulty and cost are relatively large.

• Energy consumption: Water-cooled cables need to be cooled by water pumps and other equipment, which increases energy consumption.

Conclusion

As a safe and efficient cooling method, water-cooled cables have their advantages in terms of cleanliness, energy saving, efficiency, and scalability. During use, attention should be paid to the compliance and maintenance of water-cooled cable standards.