ABB Overload Relay Selection Guide: Matching Your Motor And Application

Selecting the correct ABB overload relay begins with evaluating your motor’s full-load amps (FLA), service factor, and operating conditions. Once you know these, you can use the ABB overload relay selection chart to choose between thermal and electronic options.

Understanding the ABB Overload Relay Range

The ABB overload relay range is designed to protect motors from sustained overcurrent that leads to overheating or burnout. ABB offers two primary types:

• ABB thermal overload relay – traditional electromechanical devices using bimetallic strips to detect overload.
• ABB electronic overload relay – precise, adjustable models with trip class flexibility and wider current settings.

By covering both ends of the spectrum, ABB allows engineers to match relays to light-duty and heavy-duty applications.

How to Select an ABB Overload Relay

The following steps explain how to size, configure, and install the correct relay for your application.

Step 1: Gather Motor and Application Data

Motor nameplates provide essential information that directly determines overload protection:

• Full-Load Amps (FLA): The base reference for sizing.
• Service Factor (SF): Motors rated 1.15 can safely handle 25% above FLA, while 1.0 SF requires tighter settings.
• Locked Rotor Amps (LRA): Helps determine if a motor needs an extended startup allowance.

When selecting a thermal overload relay, ABB, this data ensures the chosen device sits within the middle of the adjustable range. For more complex applications, an electronic relay offers greater tolerance and precision.

Step 2: Match the Application

Different operating conditions influence the type of relay you choose:

• Light starting loads, such as fans or conveyors, are best served by a simple ABB thermal overload relay.
• Heavy starting loads, such as crushers or pumps, require an ABB electronic overload relay with selectable trip classes.
• Harsh temperature environments require electronic versions that compensate for fluctuations between –25°C and +50°C.

This balance is why the ABB overload relay selection chart is a valuable tool, simplifying the decision based on motor duty and environment.

Step 3: Calculate the Protection Setting

Once you know the FLA and service factor, calculate the trip setting. For motors with an SF of 1.15 or higher, multiply the FLA by 1.25. For SF 1.0 motors, multiply by 1.15. This gives you the maximum allowable overload rating. Your selected ABB overload relay range should include this number comfortably in the middle of its adjustment scale.

Step 4: Select the Right Trip Class

Trip class determines how long the relay allows overload current before tripping. ABB devices typically offer:

• Class 10/10E: Trips in 10 seconds at 600% of rated current — suitable for fast-starting motors.
• Class 20/20E: Trips in 20 seconds — common for conveyors, compressors, and pumps.
• Class 30/30E: Trips in 30 seconds — used for high-inertia loads with long start times.

Many ABB electronic overload relay models allow you to switch between these classes, providing flexibility without needing multiple part numbers.

Step 5: Ensure Compatibility with Other Components

Selecting an ABB overload relay also means checking how it works with the rest of your system. Thermal relays like the TA and TF series, or electronic models such as the E-series, often mount directly on ABB contactors, simplifying setup. Always confirm coordination with breakers or fuses since overload relays don’t protect against short circuits. For complex installations, ABB’s SOC tool can verify proper matching between relay, contactor, and protection devices.

Why Source ABB Overload Relays from Simply Buy

After working through the ABB overload relay selection steps, the next challenge is finding a supplier you can trust. Simply Buy is a leading ABB motor overload relay supplier, focused on authenticity and customer satisfaction on a global scale.

We stock both ABB thermal overload relay models (like the TA and TF ranges) and ABB electronic overload relay options with adjustable trip classes. This ensures you get the full range and can choose the relay that makes the most sense for your project.

Here’s what sets us apart:

• North America: We offer DDP (door-to-door delivery) service that eliminates customs and logistics delays.
• Russia: We provide formal customs clearance documents for government projects.
• Asia: We offer professional relay selection and competitive pricing for large-scale needs.
• Africa & Europe: We provide distributor certificates, which are available upon request to confirm authenticity.

Simply Buy also supports multi-brand sourcing. In addition to ABB relays, you can explore Schneider overload relays or compare motor starter solutions and motor controllers. Every relay from us is factory-sourced, checked, and delivered reliably.

Conclusion

Selecting the right ABB overload relay means balancing current ratings, trip classes, and application needs. Whether you need a compact thermal overload relay ABB model or a fully adjustable ABB electronic overload relay, the ABB overload relay selection chart makes the process easier.

If you want a multi-brand solution with reliable logistics and guaranteed authenticity, Simply Buy has you covered. Contact us today to learn more about our ABB relay offerings.