EATON AZ-3-D40 Miniature Circuit Breaker, 3-Pole, D-Curve, 40A, 25kA, AC

The EATON AZ-3-D40 is a high-performance 3-pole miniature circuit breaker engineered to provide reliable protection for electrical systems in industrial and commercial environments. This device is specifically designed to handle high inrush currents, making it an essential component for safeguarding electrical circuits against overloads and short circuits in demanding AC installations.

Advantages

This circuit breaker offers exceptional durability and operational reliability under heavy electrical loads. Its D-curve tripping characteristic allows it to tolerate high starting currents, which is critical for equipment such as large motors or transformers. With a high breaking capacity of 25kA, it ensures effective fault clearance, thereby protecting downstream equipment and minimizing the risk of electrical damage during a short-circuit event.

Suitable for

• Industrial machinery and motor control centers
• Commercial building electrical distribution boards
• Systems with high inductive loads
• Applications requiring robust short-circuit protection

When it may not be suitable

This device is not intended for residential lighting or standard household outlet circuits, as the D-curve tripping characteristic is specifically tuned for high-inrush applications. Using it in environments without significant inductive loads may result in delayed protection during minor faults.

Key specifications

• Number of poles: 3
• Rated current: 40A
• Tripping characteristic: D-curve
• Breaking capacity: 25kA
• System type: AC

How to use

The EATON AZ-3-D40 should be installed by a qualified electrician into a standard DIN-rail distribution board. Ensure that the supply cables are properly sized for a 40A load and that all terminal connections are tightened to the manufacturer's specified torque to prevent overheating. Once installed, the device can be manually switched on or off using the front-mounted toggle, and it will automatically trip to the off position if an overload or short circuit is detected.

What to consider before purchase

• Verify that the 40A rating matches your circuit requirements
• Ensure the D-curve characteristic is appropriate for your specific load type
• Confirm that the 25kA breaking capacity meets the short-circuit current levels of your installation
• Check available space in your distribution board for a 3-pole device

Usage recommendations

For optimal performance and safety, regularly inspect the terminal connections for tightness and ensure the device is kept free from dust and moisture. Do not attempt to bypass the tripping mechanism or use the breaker as a primary manual switch for frequent load cycling.