Introduction: The Hidden Factor Behind Servo System Reliability

In modern industrial automation, precision is everything.

Robotic arms must move accurately. CNC machines must maintain positioning accuracy. Automated production lines must operate continuously without interruption.

Behind every high-performance servo system, there is a small but critical component:

The servo cable.

Many engineers carefully select:

• Servo motors
• Servo drives
• Controllers
• Motion systems

But the cable connecting these components is sometimes overlooked.

A common question is:

Should I choose a shielded servo cable or an unshielded servo cable?

At first glance, both cables may look similar.

They can carry power.
They can connect servo motors.
They can fit the same equipment.

However, inside an industrial environment, the difference can determine whether your automation system runs smoothly — or experiences unexpected problems.

What Is a Shielded Servo Cable?

A shielded servo cable is designed with an additional protective layer that reduces electromagnetic interference (EMI).

The shielding layer is usually made from:

• Copper braid
• Aluminum foil
• Combination shielding structures

Its purpose is to block external electrical noise and prevent interference from affecting signal transmission.

A typical shielded servo cable structure includes:

This design helps maintain stable communication between:

• Servo drive
• Servo motor
• Encoder system

What Is an Unshielded Servo Cable?

An unshielded servo cable does not contain an additional electromagnetic protection layer.

It is mainly used in environments where electromagnetic interference is low.

Typical applications include:

• Simple automation equipment
• Short cable distances
• Low-power motion systems
• Clean electrical environments

Advantages include:

✔ Lower cost
✔ Smaller diameter
✔ Easier installation

However, because there is no shielding protection, performance may be affected in environments with strong electrical noise.

1. Electromagnetic Interference (EMI) Protection

This is the most important difference.

Modern factories contain many sources of electromagnetic noise:

• Frequency converters
• Servo drives
• Motors
• Welding equipment
• Power cables

These devices can generate electrical interference that affects sensitive signals.

For servo systems, interference can cause:

• Incorrect positioning
• Communication errors
• Motor vibration
• Reduced accuracy

A shielded servo cable acts as a protective barrier, helping maintain stable signal transmission.

2. Motion Accuracy and System Performance

Servo motors rely on feedback signals.

The encoder continuously sends information about:

• Position
• Speed
• Rotation angle

The servo controller uses this feedback to make real-time adjustments.

If interference disrupts these signals, the system may experience:

• Position deviation
• Slow response
• Unexpected movement

For applications requiring high precision, such as:

• CNC machines
• Semiconductor equipment
• Robotic systems

a shielded servo cable is usually the safer option.

3. Installation Environment Matters

The right choice depends on where the cable operates.

Choose Shielded Servo Cable When:

Your equipment includes:

✔ Servo drives
✔ Frequency converters

✔ Industrial robots
✔ CNC machines
✔ Automated production lines

Your environment has:

✔ High electromagnetic noise
✔ Long cable distances
✔ Multiple power cables nearby
✔ High precision requirements

Unshielded Servo Cable May Be Suitable When:

✔ The environment is electrically clean

✔ Cable length is short

✔ The system has low sensitivity requirements

✔ Cost optimization is important

4. Flexible Movement Requirements

Industrial automation cables are often exposed to mechanical stress.

Examples:

• Robot arms
• Drag chains
• Moving machinery

A good servo cable must handle:

• Continuous bending
• Twisting
• Acceleration
• High-speed movement

For dynamic applications, shielding alone is not enough.

The cable should also have:

• Fine stranded copper conductors
• Flexible insulation materials
• High-flex jacket design

A shielded but poorly designed cable may still fail under continuous movement.

Common Mistakes When Choosing Servo Cable

Mistake 1: Choosing Only Based on Price

Many customers choose unshielded cables because they are cheaper.

However, the cost of cable failure can be much higher:

• Machine downtime
• Production loss
• Maintenance costs
• Replacement labor

The cable is a small investment compared with the entire automation system.

Mistake 2: Assuming All Servo Cables Are the Same

Two servo cables may look identical externally.

But their differences may include:

• Shielding structure
• Conductor quality
• Flexibility performance
• Jacket material
• Signal protection capability

The internal design determines long-term reliability.

Mistake 3: Ignoring Cable Installation

Even the best shielded servo cable may not perform properly if installed incorrectly.

Important considerations:

• Proper grounding
• Correct bending radius
• Separation from high-voltage cables
• Suitable cable routing

How to Select the Right Servo Cable for Your Application

Before choosing a servo cable, ask:

1. What type of equipment will use the cable?

Examples:

• Robot arm?
• CNC machine?
• Packaging machine?
• Automated assembly line?

2. Does the system require encoder feedback?

If yes, signal protection becomes critical.

3. Is the cable installed in a high-noise environment?

If your equipment operates near:

• Motors
• Drives
• Inverters

shielding is strongly recommended.

4. Does the cable move continuously?

For moving applications, choose:

• High-flex servo cable
• Drag chain compatible cable
• Robot cable

Why AEIN Focuses on Reliable Servo Cable Solutions

At AEIN Cable, we understand that cable performance directly affects automation system reliability.

A servo cable is not simply a connection between two components.

It is responsible for:

• Power transmission
• Signal accuracy
• Motion stability
• Long-term equipment operation

AEIN provides industrial cable solutions including:

• Shielded servo cables
• Flexible servo cables
• Drag chain cables
• Robot cables
• Customized cable solutions

Our goal is to help automation manufacturers select cables that match their real working conditions.

Final Thoughts: Shielded or Unshielded Servo Cable?

There is no universal answer.

The right choice depends on:

• Application environment
• EMI conditions
• Motion requirements
• Precision requirements
• Cable installation conditions

For simple, low-noise applications, an unshielded servo cable may be sufficient.

But for modern industrial automation systems requiring stability, accuracy, and long service life:

A shielded servo cable is often the better investment.

Because in automation, a small cable decision can have a big impact on overall system performance.