Circuit breakers are critical components in electrical systems, providing protection against overloads and short circuits. Among the leading manufacturers of high-quality circuit breakers is Terasaki, a brand known for its reliability and advanced technology.

In this blog, we will explore two specific models:

• Breaker 63A 4P Terasaki (4-Pole)

• Breaker 63A 3P Terasaki (3-Pole)

We will discuss their differences, applications, advantages, and key considerations when choosing between them.

1. What is a Terasaki Circuit Breaker?

Terasaki Electric Co., Ltd. is a Japanese company renowned for manufacturing high-performance circuit breakers, switchgear, and power distribution equipment. Terasaki breakers are widely used in industrial, commercial, and marine applications due to their durability, precision, and safety features.

Key features of Terasaki breakers include:

• High breaking capacity

• Compact design

• Reliable overload and short-circuit protection

• Suitable for harsh environments

2. Understanding Pole Configuration in Circuit Breakers

The terms 4P (4-Pole) and 3P (3-Pole) refer to the number of poles in a circuit breaker, which determines how many live conductors it can interrupt.

• 4P Breaker (4-Pole):

  • Interrupts four conductors (3 phases + 1 neutral)

  • Used in systems where neutral disconnection is required

  • Common in 3-phase + neutral distribution systems

• 3P Breaker (3-Pole):

  • Interrupts three conductors (3 phases only)

  • Neutral remains uninterrupted

  • Used in 3-phase systems without neutral disconnection

3. Breaker 63A 4P Terasaki – Features and Applications

Specifications:

• Current Rating: 63A

• Poles: 4 (L1, L2, L3, N)

• Voltage Rating: Typically 415V AC or higher

• Breaking Capacity: High (depends on model)

Applications:

1. Three-Phase Systems with Neutral Protection

   • Used where the neutral must be disconnected for safety (e.g., generator switching, isolation).

2. Industrial Power Distribution

   • Protects machinery and large equipment requiring a neutral connection.

3. Marine and Offshore Applications

   • Ensures full circuit isolation in ships and offshore platforms.

4. Critical Infrastructure (Hospitals, Data Centers)

   • Prevents neutral-related faults in sensitive environments.

Advantages:

• Complete Circuit Isolation: Ensures all live and neutral conductors are disconnected.

• Enhanced Safety: Reduces risks in unbalanced load conditions.

• Compliance with Electrical Codes: Required in some regions for specific installations.

4. Breaker 63A 3P Terasaki – Features and Applications

Specifications:

• Current Rating: 63A

• Poles: 3 (L1, L2, L3)

• Voltage Rating: Typically 415V AC or higher

• Breaking Capacity: High (depends on model)

Applications:

1. Three-Phase Motors and Industrial Equipment

   • Used in motors, pumps, and compressors where neutral is not required.

2. Commercial Buildings

   • Protects HVAC systems, elevators, and lighting panels.

3. Renewable Energy Systems (Solar/Wind)

   • Safeguards inverters and power distribution units.

4. General Power Distribution Panels

   • Common in standard 3-phase power networks.

Advantages:

• Cost-Effective: Fewer poles mean lower cost compared to 4P breakers.

• Simpler Installation: No need for neutral disconnection in most cases.

• Wider Availability: More commonly stocked than 4P models.

5. Key Differences Between 4P and 3P Terasaki Breakers

6. How to Choose Between 4P and 3P Breakers?

When to Use a 4P Breaker?

✔ If neutral switching is required (e.g., transfer switches, isolation).
✔ In unbalanced load systems where neutral current is significant.
✔ For critical installations (hospitals, data centers, ships).

When to Use a 3P Breaker?

✔ For balanced 3-phase loads (motors, pumps).
✔ When neutral disconnection is unnecessary.
✔ For cost-sensitive projects where 4P is not mandated.

7. Installation and Maintenance Tips

• Follow Manufacturer Guidelines: Terasaki provides detailed installation manuals.

• Check Voltage Ratings: Ensure compatibility with your system.

• Regular Testing: Inspect for wear, overheating, and proper trip functionality.

• Use Qualified Electricians: Proper installation is crucial for safety.

8. Conclusion

Choosing between a 63A 4P Terasaki and a 63A 3P Terasaki breaker depends on your system’s requirements:

• 4P offers full isolation (including neutral) for critical applications.

• 3P is ideal for standard 3-phase systems without neutral interruption.

Both breakers provide excellent protection, but understanding their differences ensures optimal performance and safety.

Final Recommendation:

• For industrial and marine use → 4P (full protection).

• For general machinery and commercial use → 3P (cost-effective).

By selecting the right breaker, you enhance system reliability, safety, and efficiency.