Product Description
The Allen-Bradley 140U-MTD3-D45 is a replaceable thermal-magnetic trip unit for M-frame circuit breakers (Bulletin 140U series) rated at 450 Amps at 40C, with a thermal trip setting of 450 Amps and an adjustable magnetic trip range of 2250-4500 Amps. Its M-frame design includes metal tabs and angled load ends to prevent incorrect installation in Q-frame devices. Before installation, inspect the unit, install any internal accessories, and ensure the circuit breaker is tripped. Verify the nameplate information matches system requirements. Adjust the magnetic settings on each pole using a screwdriver, ensuring the adjustment buttons are set at detents. The factory-sealed cover prevents calibration tampering. This 140U series device complies with UL 489, CE, CSA, and KEMA-KEUR standards.
Is Your Device Showing These Signs?
The Allen Bradley 140U-MTD3-D45 molded case circuit breaker commonly experiences issues such as nuisance tripping due to incorrect overload settings or thermal magnetic trip unit malfunction. Corrosion on the line and load side terminals is a frequent problem, leading to increased resistance and potential overheating. Failed or damaged operating mechanisms prevent proper breaker operation, necessitating replacement or repair. Furthermore, the breaker's inability to maintain proper insulation resistance results in ground faults and compromised circuit protection.
Technical specifications
The Allen-Bradley 140U-MTD3-D45 is a 450A thermal-magnetic trip unit designed for M-frame (Bulletin 140U) circuit breakers. It features a 450A thermal trip and an adjustable magnetic trip range of 2250-4500A. Its design prevents incorrect installation in smaller Q-frame breakers. Installation requires inspection, accessory installation, ensuring the breaker is tripped, and verifying nameplate compatibility. Magnetic trip settings are adjustable with a screwdriver, and a sealed cover prevents tampering. The device complies with UL 489, CE, CSA, and KEMA-KEUR standards.
Our Repair Process for the
140U-MTD3-D45
Our repair process for the Allen Bradley 140U-MTD3-D45 molded case circuit breaker begins with a thorough inspection to identify specific faults, including verification of overload settings, thermal magnetic trip unit functionality, and assessment of terminal corrosion. Terminals are cleaned and treated to remove corrosion and ensure optimal conductivity. Operating mechanisms are meticulously examined, and any failed or damaged components are replaced or repaired to guarantee proper breaker operation. Insulation resistance is rigorously tested, and if found to be deficient, the breaker undergoes comprehensive refurbishment to eliminate ground faults and restore circuit protection integrity. The breaker is then subjected to rigorous testing to confirm adherence to original performance specifications before being returned.
Your Guarantee: Warranty & Lifetime Support
Your satisfaction is our top priority, and we confidently stand behind the quality of our repairs. That's why every repair service is covered by our comprehensive 24-month warranty. Furthermore, we offer lifetime phone support – if you have questions or need assistance related to our repair down the road, we're here to help. Our service commitment is straightforward: we guarantee our work, and if you're not satisfied, we will make it right. Learn More about our Repair process.
Comprehensive Repairs You Can Depend On
We take immense pride in the quality and reliability of our work. Our process goes beyond simply fixing the immediate problem. We perform a comprehensive inspection of your main board (or other equipment) and proactively replace components known to be failure-prone or showing signs of potential future failure. Before any item is returned, it undergoes rigorous functional testing to ensure it meets performance specifications and operates flawlessly. Visit our main Repair Services page to learn more.
Save Significantly
Our primary goal is to save you hundreds, or even thousands, of dollars compared to the cost of new equipment replacement. By repairing existing components, we provide an economical solution that is also eco-friendly. At Roc Industrial, our commitment to integrity and community drives our consistent growth and ensures you receive a reliable, cost-effective solution.
Please Note: Roc Industrial operates as an independent service provider and is not an authorized distributor for the manufacturers or brands mentioned. Consequently, the original manufacturer's warranty is not applicable to items repaired or sold by us. Roc Industrial provides its own 2-year warranty on all repair services performed.