The difference between control cable and power cable: analysis of key differences in industrial applications

​In modern electrical and automation systems, cables serve as the essential medium for energy transmission and signal communication. From factory equipment operations to urban power grid supply, and even precision control of smart instruments, all these processes rely on cable support. However, control cables and power cables—though visually similar—differ fundamentally in their functional roles, structural designs, and practical applications. Selecting them incorrectly may lead to equipment malfunctions, signal interference, and even safety incidents, ultimately causing economic losses.​
For engineers, clearly distinguishing between two types of cables is fundamental to system design. For procurement teams, understanding their differences prevents wasteful purchases. For project managers, proper cable selection ensures both efficiency and cost control. This article rigorously examines core distinctions through six dimensions: definitions, construction, electrical characteristics, application scenarios, safety standards, and cost considerations. By presenting key information through comparative tables, it provides precise guidance for practical implementation. ​
Definition and Core Use: The essential divergence between energy transmission and signal control ​
The design intention of the two types of cables is completely different, which directly determines their role in the industrial system.​Power cable: "energy transmission channel" ​ for industrial systems
The core function of power cables is to transmit high-voltage, high-current electrical energy, enabling energy transfer from power generation sources (such as power plants and substations) to end-users (including industrial equipment and building facilities). They must overcome line losses, withstand the insulation stress caused by high voltages, and mitigate heat generation from high currents, ensuring stable power delivery to the load end.​
In practical applications, power cables are extensively used across energy, industrial, and infrastructure sectors: They connect generators and transformers in power plants, supply electricity to high-power equipment like motors and furnaces in industrial workshops, and form distribution networks for residential communities and commercial complexes in cities. For example, a 300kW industrial motor requires a power cable with a cross-sectional area of ≥70mm² to meet its operational current demands.​
Control cable: "signal interaction link" of the automation system ​
Control cables transmit low-voltage, low-current signals and commands rather than high-power electrical energy. They serve as the critical link in the "signal acquisition-command issuance-status feedback" process within automation systems. These cables must ensure accurate signal transmission while preventing control errors caused by interference.​
Its applications are primarily concentrated in scenarios requiring high signal reliability: connecting PLC (Programmable Logic Controllers) with sensors and actuators in automated production lines, monitoring pipeline pressure and flow in petrochemical fields, and controlling elevator operations and air conditioning activation in smart buildings. For instance, temperature sensors on intelligent production lines must transmit data to PLC via control cables, which then issue temperature control commands. The signal accuracy of these cables directly impacts product quality.​
Structural differences: function-oriented structural design 
The cable structure should match the core function. Power cable focuses on "bearing capacity", control cable focuses on "signal integrity", the difference is mainly reflected in the conductor, insulation sheath and shielding layer. ​Conductor: size and material compatibility ​
Electrical cables: Designed to carry high currents, these cables feature larger conductor cross-sections (typically 10-240mm², with specialized variants exceeding 400mm²). The primary materials are copper (high conductivity and reliability) and aluminum (cost-effective and lightweight). For example, 120mm² copper conductors in 0.6/1kV cross-linked polyethylene insulated cables can carry up to 300A over long-term operation, meeting the requirements of most industrial motors.​
Control cables transmit extremely low currents (ranging from milliamps to amperes) through conductors with smaller cross-sectional areas (typically 0.5-2.5mm²) and multi-core configurations (2-24 cores), enabling simultaneous signal transmission and simplified wiring. These cables are predominantly copper-based, ensuring low-loss signal transfer. For instance, control cables connecting proximity switches can meet requirements using 0.75mm² copper conductors.​
Insulation and sheath: balance between voltage resistance and flexibility​
Electrical cables: Designed to withstand high voltages (0.6kV to 35kV and above), with thicker insulation layers (e.g., 10kV cables require ≥4.5mm insulation). The primary material is cross-linked polyethylene (XLPE) with excellent temperature resistance (90℃°C) and superior insulation properties. The sheath emphasizes mechanical strength and environmental durability, featuring steel tape reinforcement with polyethylene sheathing for underground installations, and weather-resistant chloroprene rubber sheathing for overhead applications, ensuring long-term stability.​
Control cables: Low voltage (typically ≤300V), with thin insulation layers (0.5-1.0mm). The main materials are polyvinyl chloride (PVC) and polyethylene (PE). The sheath emphasizes flexibility and environmental friendliness. For industrial applications, flexible PVC or elastomer sheaths are used to facilitate installation in confined spaces. In the food and pharmaceutical industries, RoHS-compliant sheaths are employed to prevent contamination.​
Shield layer: Different requirements for anti-interference ​
Electrical cables primarily transmit energy, with their electromagnetic fields being the main interference source. Most low-voltage cables (e.g., 0.6/1kV) do not require shielding. Shielding is only applied when near sensitive equipment (e.g., medical devices) or in environments with strong interference (e.g., radar stations) to minimize effects on surrounding devices.​
Control cables: As weak signals are susceptible to electromagnetic interference, shielding layers are a standard feature. Common types include copper wire braiding (shielding effectiveness ≥80dB, suitable for bending scenarios), copper tape wrapping (coverage ≥90%, ideal for fixed installations), and aluminum-plastic composite tape shielding (cost-effective for civilian applications). For high-demand environments like petrochemical facilities, dual-layer shielding ensures signal stability. ​
Electrical characteristics: clear differentiation of performance boundaries ​
The electrical characteristics directly determine the application scope of the cable, and the design objectives of the two in voltage, current and signal transmission are completely different, so there is no possibility of general substitution. ​
Voltage rating: difference in voltage withstand capacity ​
Electrical cables: With extensive voltage coverage, they offer corresponding specifications for low-voltage (0.6/1kV for equipment distribution and residential wiring), medium-voltage (6/10kV to 21/35kV for urban power grids and industrial park transmission), and high-voltage (64/110kV to 127/220kV for regional grid transmission). For example, industrial parks typically use 35kV medium-voltage cables from substations to main distribution rooms, 10kV medium-voltage cables in workshops, and 0.6/1kV low-voltage cables for equipment. ​
Control cable: the rated voltage is low, mostly 0.3/0.5kV (300V/500V), special high voltage equipment control circuit 0.6/1kV cable, working voltage far below the rated value (such as PLC and solenoid valve connection with 24V DC or 220V AC), leaving a safety margin.​
Current capacity: the gap in current carrying capacity ​
Power cables are designed for high current-carrying capacity, with their core performance metric being the ability to meet high-power demands. Taking 0.6/1kV XLPE cables (air-laid, 30℃ ambient temperature) as an example: A 10mm² copper conductor can carry approximately 65A (for a 13kW motor), while 50mm² cables handle about 150A (for 31kW motors) and 120mm² cables manage around 300A (for 62kW motors). In practical applications, the actual current-carrying capacity should be adjusted based on installation conditions (e.g., applying a 0.8 factor when densely installed).​
Control cable: Low current-carrying capacity. The 1.0mm² copper conductor has a long-term allowable current of approximately 10A, with actual operating currents ≤1A (e.g., PLC signal current around 200mA and sensor feedback current <10mA). Design emphasis focuses on current stability to prevent signal distortion caused by poor contact (e.g., abnormal liquid level sensor signals triggering water replenishment misoperations).​

Signal transmission: Different performance orientations ​

Power cables: Transmit "electrical signals," with core specifications including load capacity, voltage drop, and power loss. For example, a 100-meter cable with 50mm² copper conductor can maintain a voltage drop of approximately 0.57V when carrying 150A current. This performance meets operational requirements within a 380V motor ±5% voltage deviation range.​
Control cables transmit "weak signals" (analog or digital) with precision as their core characteristic, measured by signal attenuation and interference resistance. For example, in 4-20mA analog signal transmission, cables must maintain attenuation ≤1% while using shielding layers to block external interference, preventing data distortion that could compromise control accuracy. ​
Application scenarios: Practical implementation of functional matching ​
The application scenarios of the two types of cables are clearly divided due to the difference in functions, and there is no overlapping replacement space. ​
Typical applications of power cables ​
Energy field: the connection of generators and transformers in power plants, the underground laying of high-voltage transmission lines, and the power transmission between substations;​
Industrial field: power supply for motors, compressors, furnaces and other high-power equipment in the factory workshop, power distribution network of production lines; ​
Infrastructure: power distribution system for urban residential communities, commercial complexes and office buildings, power supply lines for municipal street lights and traffic signals.​
Typical applications of control cables ​
Automation and robotics: robot joint action control, position feedback in intelligent production line, PLC and actuator (electromagnetic valve, contactor) connection; ​
Instrumentation: connection of pressure, flow and temperature sensors to control cabinet in petrochemical pipeline, signal monitoring of laboratory precision instruments; ​
Intelligent control: signal transmission of elevator operation status feedback, air conditioning system start/stop control and mall lighting intelligent control in intelligent building. ​
Security and standards: hard requirements for compliance ​
Cables should meet industry standards to ensure safety, and the two types of cables have different standards. ​
Standard requirements for power cables ​
The core requirements are high voltage tolerance and fire safety compliance. These must meet standards such as GB/T 12706 "Sheathed Insulated Power Cables with Rated Voltages from 1kV to 35kV" and IEC 60502 "Sheathed Insulated Power Cables with Rated Voltages from 1kV to 30kV". The insulation layer must withstand breakdown, while the sheath should be flame-retardant (e.g., flame retardant rating per GB/T 19666). In specific scenarios, fire resistance requirements must be satisfied (e.g., for power distribution in high-rise buildings). ​
Control cable standard requirements ​
The core requirements are signal integrity and electromagnetic interference resistance, which must comply with standards such as GB/T 9330 "Plastic Insulated Control Cables", IEC 60227 (PVC Insulated Control Cables), and IEC 60245 (Rubber Insulated Control Cables). The shielding layer must meet performance specifications (e.g., copper braiding coverage ≥85%), while the insulation layer should demonstrate temperature resistance and environmental compliance (e.g., RoHS certification). ​
Cost and practical considerations: balance between economy and operability​
Cost and installation convenience vary according to structure and material, so it should be selected according to project requirements. ​
cost variance ​
Power cables: They have large conductor cross-sections, thick insulated sheaths, and high copper/aluminum content, resulting in higher costs. For example, a 100-meter 120mm² copper conductor 0.6/1kV XLPE cable costs about 5-8 times that of a 24-core 1.0mm² control cable of the same length;​
Control cable: the conductor is thin, the structure is simple, the cost is lower, and the multi-core design reduces the number of laying, further reducing the total construction and material costs. ​
Practical considerations​
Power cable: heavy weight (e.g. 120mm² cable about 1.2kg per meter), poor flexibility, laying needs mechanical assistance (e.g. cable wire laying frame), suitable for direct burial, overhead and other fixed laying scenarios, not suitable for narrow space or frequent bending;​
Control cable: light weight (e.g., 24-core 1.0mm² cable about 0.3kg per meter), good flexibility, can be manually laid, suitable for control cabinet internal, equipment gap and other narrow space, and can adapt to frequent bending scenarios such as robot arm.​
Quick Comparison Table: Core differences at a glance ​
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Characteristic	electric power cable	control cable
Main application	High power energy transmission	Signal/control command transmission
Voltage capacity	Medium and high voltage (0.6kV-35kV and  more than ）	Low voltage (≤0.5kV, special ≤1kV)
Conductor dimensions	Large cross section (10-240mm² and above)	Small cross section (0.5-2.5mm², multi-core)
Shielding layer	Rare (for special scenarios only)	Common (copper wire braiding/copper strip winding, etc.)
Application scenarios	Power distribution, motor power supply, power transmission	Automation control, instrumentation, equipment signal interaction
Core standards	GB/T 12706、IEC 60502	GB/T 9330、IEC 60227/60245
Prime cost	Higher (more material)	Lower (simple structure)
Difficulty of laying	Large (heavy, hard, requires mechanical assistance)	Small (light, soft, can be manually applied)

Conclusion ​
Although control cables and power cables look similar, they are fundamentally different in definition, construction, electrical characteristics, and application scenarios: Power cables are "energy transmitters" that focus on high voltage and large current carrying capacity; control cables are "signal transmitters" that focus on high precision and anti-interference.​
Proper equipment selection is crucial for ensuring system efficiency, safety, and cost control. Engineers must design solutions by considering factors like equipment power, voltage levels, and installation environments. Procurement teams should make strategic purchases based on standards and specifications. Project managers need to balance cost-effectiveness with practicality. When in doubt about equipment selection, consult cable manufacturers or suppliers to obtain customized solutions, thereby avoiding risks and losses caused by poor decisions.