Overload Relay Function and Role in Industrial Motor Protection
In modern industrial environments, electric motors are the backbone of production—driving pumps, compressors, conveyors, machine tools, and countless process systems. Protecting these motors against abnormal operating conditions is not optional; it is essential for safety, uptime, and asset longevity. This is where an overload relay plays a critical role.
An overload relay is a motor protection device designed to disconnect power when a motor draws excessive current over a sustained period. Unlike short-circuit protection devices, which respond instantly to very high fault currents, overload relays focus on thermal stress caused by prolonged overcurrent. If left unaddressed, such stress can degrade insulation, reduce motor life, and lead to costly breakdowns.
In industrial motor control circuits, overload relays are typically installed in coordination with contactors and circuit breakers. Together, these components form a complete protection and control system that safeguards motors from overheating while allowing normal starting and running currents. For engineers, panel builders, and maintenance teams, selecting the right relay is a foundational design decision that directly impacts reliability and compliance.
Why Overload Relay Is Critical in Indian Industrial Applications
Indian industries operate under diverse and demanding conditions—voltage fluctuations, high ambient temperatures, frequent motor starts, variable loads, and sometimes harsh environments. These factors increase the likelihood of motor overload if protection is not properly engineered.
Overload relays are especially critical in India’s:
- Manufacturing plants – where continuous-duty motors run for long hours.
- Process industries – such as cement, steel, chemicals, and paper.
- Infrastructure projects – including water treatment and material handling.
- OEM-built machinery – where standardized motor protection ensures long-term reliability.
In these applications, overload relays help prevent unplanned downtime, reduce maintenance costs, and improve workplace safety. Their widespread adoption across Indian industrial panels reflects both regulatory expectations and practical engineering best practices.
Top-Selling Overload Relay Models from Leading Brands in India
India’s industrial market is dominated by a few globally trusted manufacturers whose relay ranges have proven performance across sectors. Below are the top-selling models widely specified by engineers, panel builders, and OEMs, based on reliability, availability, and application versatility.
Schneider Electric Overload Relay – TeSys and Easy TeSys Series
Schneider Electric is one of the most trusted and top-selling brands for overload relays in India’s industrial market. Its TeSys and Easy TeSys series are widely adopted by OEMs, panel builders, and industrial plants due to their consistent performance, high safety standards, and seamless compatibility with Schneider contactors. Highly popular models include the TeSys LRD series (LRD03, LRD10, LRD14, LRD21, LRD332) along with LRE07/LRE08 from the Easy TeSys range, making Schneider Electric a preferred choice for reliable motor protection across diverse applications.
Most Preferred Schneider Electric TeSys and Easy TeSys Overload Relays in Indian Industry
The Schneider Electric TeSys Deca LRD03 thermal overload relay provides accurate Class 10 motor protection for low-current industrial applications and is widely used in OEM machinery and control panels.
It is ideal for small motor applications, offering stable tripping performance and long service life in continuous-duty environments.
Product Specifications
- Brand – Schneider Electric
- Model – TeSys – Schneider Electric
- Reference No – LRD03
- Overload Range – 0.25 – 0.4 A
- Mounting Type – Direct Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling Schneider Electric TeSys Overload Relay in India
The Schneider Electric Easy TeSys LRE07 thermal relay offers reliable Class 10 motor protection for low to medium current industrial applications and is widely used in OEM control panels.
It supports direct and independent mounting and is fully compatible with Easy TeSys contactors for standardized motor starter systems.
Product Specifications
- Brand – Schneider Electric
- Model – EasyPact TVS– Schneider Electric
- Reference No – LRE07
- Overload Range – 1.6 – 2.5 A
- Mounting Type – Direct & Independent Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling Schneider Electric Easy TeSys Overload Relay in India
L&T (Lauritz Knudsen) Overload Relay – MN, ML and RTO Series
Lauritz Knudsen (L&T) is a well-established and trusted Indian brand in the industrial electrical segment, widely known for its rugged and reliable relay solutions. The MN, ML and RTO series relays from L&T are extensively used across Indian industrial panels, OEM machinery, and infrastructure projects due to their robust construction, stable thermal performance, and suitability for harsh operating conditions. Popular models such as MN2, MN5, and ML2 are commonly specified for dependable motor protection in diverse industrial applications.
Most Preferred L&T MN, ML and RTO Series Overload Relays in Indian Industry
The Lauritz Knudsen MN2 thermal overload relay provides reliable Class 10 motor protection for low-current industrial applications and is widely used in OEM control panels.
It is suitable for small motor applications and offers direct mounting compatibility with MNX series contactors for standardized motor starter systems.
Product Specifications
- Brand – Lauritz Knudsen (Formerly L&T Switchgear)
- Model – MN Series – Lauritz Knudsen
- Reference No – SS94141OOPO
- Overload Range – 1.4 – 2.3 A
- Mounting Type – Direct Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling L&T MN2 Overload Relay in India
The Lauritz Knudsen MN5 thermal overload relay provides dependable Class 10 motor protection for medium to high current industrial applications and is widely used in OEM panels and motor control centers.
It is suitable for motors with higher load requirements and offers direct mounting compatibility with MNX50 to MNX80 contactors for robust starter configurations.
Product Specifications
- Brand – Lauritz Knudsen (Formerly L&T Switchgear)
- Model – MN Series – Lauritz Knudsen
- Reference No – SS94135OOBO
- Overload Range – 9 – 15 A
- Mounting Type – Direct Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling L&T MN5 Overload Relay in India
The Lauritz Knudsen ML2 / ML3 thermal overload relay provides reliable Class 10 motor protection for small to medium industrial motor applications and is widely used in compact control panels.
It supports direct mounting with ML2 to ML3 contactors, making it ideal for space-optimized and standardized motor starter designs.
Product Specifications
- Brand – Lauritz Knudsen (Formerly L&T Switchgear)
- Model – ML Series – Lauritz Knudsen
- Reference No – SS91859OOAO
- Overload Range – 9 – 14 A
- Mounting Type – Direct Mounting
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling L&T ML2 Overload Relay in India
The Lauritz Knudsen RTO-3 thermal overload relay delivers reliable Class 10 motor protection for high-current industrial motor applications and is commonly used in heavy-duty control panels.
It is suitable for large motors and supports direct mounting with MO80 to MO110 contactors for robust and dependable motor starter systems.
Product Specifications
- Brand – Lauritz Knudsen (Formerly L&T Switchgear)
- Model – RTO Series – Lauritz Knudsen
- Reference No – CS96313OOJO
- Overload Range – 60 – 78 A
- Mounting Type – Direct Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling L&T RTO Overload Relay in India
Siemens Overload Relay – 3UA, 3RU, & 3RB Series
Siemens provides a comprehensive range of 3UA, 3RU, and 3RB overload relays for reliable industrial motor protection. The 3UA Series (Thermal) is widely used for small to high-current motors with models like 3UA5000-1G, 3UA5200-1H/J, and 3UA5500-2Q. The 3RU Series offers compact thermal and solid-state options such as 3RU2116-4AB0, ideal for contactor mounting in modern panels. For precise, high-accuracy protection, the 3RB Series electronic relays, including 3RB30261PB0, provide microprocessor-based performance for critical industrial applications.
Most Preferred Siemens 3UA, 3RU, & 3RB Series Overload Relays in Indian Industry
1. Siemens Sirius 3UA5 Suitable For 3TF32/33 Contactors Thermal Overload Relay 3UA5200-1G
The Siemens 3UA5200-1G thermal relay provides reliable Class 10 motor protection for low to medium current industrial motors and is widely used in OEM panels and motor control centers.
It offers precise tripping performance and direct mounting compatibility with Siemens 3UA contactors for standardized motor starter applications.
Product Specifications
- Brand – Siemens
- Model – 3UA Series – Siemens
- Reference No – 3UA5200-1G
- Overload Range – 4 – 6.3 A
- Mounting Type – Contactor Mounting
- Reset Type – Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling Siemens 3UA Series Overload Relay in India
2. Siemens Sirius 3RU2 Suitable For S00 Size 3RT Contactor Thermal Overload Relay 3RU2116-4AB0
The Siemens 3RU2116-4AB0 thermal overload relay provides reliable Class 10 motor protection for medium-current industrial motors and is widely used in motor control centers and OEM panels.
It supports direct mounting with S00 size 3RT contactors and delivers precise tripping performance for standardized motor starter applications.
Product Specifications
- Brand – Siemens
- Model – 3RU Series – Siemens
- Reference No – 3RU2116-4AB0
- Overload Range – 11 – 16 A
- Mounting Type – Direct Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling Siemens 3RU Series Overload Relay in India
3. Siemens Sirius 3RB3 Microprocessor Based Suitable For S0 Size Contactor Overload Relay 3RB30261PB0
The Siemens 3RB30261PB0 microprocessor-based overload relay provides precise Class 10 motor protection for low-current industrial motors and is widely used in automated systems and OEM panels.
It supports contactor mounting for S0 size Siemens contactors and delivers high-accuracy protection with enhanced diagnostics for critical motor applications.
Product Specifications
- Brand – Siemens
- Model – 3RB Series – Siemens
- Reference No – 3RB30261PB0
- Overload Range – 1 – 4 A
- Mounting Type – Contactor Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Microprocessor Based
Top-Selling Siemens 3RB Series Overload Relay in India
ABB Overload Relay – TA Series
ABB’s TA Series thermal overload relays deliver reliable motor protection for industrial applications of all sizes. The TA25DU-14M offers compact and versatile protection, ideal for standard starter panels, while the TA200DU-150 is designed for high-current, heavy-duty motors. These relays provide stable tripping, easy adjustment, and dependable thermal protection. ABB TA relays are widely trusted across Indian industries for both OEMs and panel builders.
Most Preferred TA Series Overload Relays in Indian Industry
The ABB TA25 thermal overload relay provides reliable Class 10 motor protection for small to medium industrial motors and is widely used in starter panels and OEM machinery.
It supports direct mounting with a wide range of ABB contactors and offers stable tripping performance with both auto and manual reset options.
Product Specifications
- Brand – ABB
- Model – TA Series – ABB
- Reference No – 1SAZ211201R2045
- Overload Range – 10 – 14 A
- Mounting Type – Direct Mounting
- Reset Type – Auto / Manual Reset
- Trip Class – Class 10
- Operating Type – Thermal
Top-Selling ABB TA Series Overload Relay in India
Top-Selling Overload Relays by Brand & Current Range (India)
The following comparison highlights the most widely used overload relay models across Indian industries, categorized by brand and motor current range. This table helps engineers, OEMs, and procurement teams quickly identify suitable relay options based on application requirements and operating current.
| Brand | Series / Model | Current Range | Trip Class | Operating Type | Best Used For |
| Schneider Electric | TeSys LRD03 | 0.25 – 0.4 A | Class 10 | Thermal | Small OEM machines, control panels |
| Schneider Electric | TeSys LRD10 | 4 – 6 A | Class 10 | Thermal | Pumps, fans, conveyors |
| Schneider Electric | TeSys LRD21 | 12 – 18 A | Class 10 | Thermal | General industrial motors |
| Schneider Electric | Easy TeSys LRE07 | 1.6 – 2.5 A | Class 10 | Thermal | Cost-effective OEM applications |
| L&T (Lauritz Knudsen) | MN2 | 1.4 – 2.3 A | Class 10 | Thermal | Rugged industrial environments |
| L&T (Lauritz Knudsen) | MN5 | 9 – 15 A | Class 10 | Thermal | MCC panels, medium-duty motors |
| L&T (Lauritz Knudsen) | RTO-3 | 60 – 78 A | Class 10 | Thermal | Heavy-duty & high-current motors |
| Siemens | 3UA5200-1G | 4 – 6.3 A | Class 10 | Thermal | Standard Siemens starter panels |
| Siemens | 3RU2116-4AB0 | 11 – 16 A | Class 10 | Thermal | Compact MCC and OEM panels |
| Siemens | 3RB30261PB0 | 1 – 4 A | Class 10 | Electronic | High-precision & automated systems |
| ABB | TA25DU-14M | 10 – 14 A | Class 10 | Thermal | General industrial starter panels |
| ABB | TA75DU | 36 – 52 A | Class 10 | Thermal | Heavy-duty industrial motors |
How to Choose the Right Overload Relay for Your Application
Selecting the correct overload relay is a technical decision that must account for multiple parameters:
- Motor Full Load Current (FLC): The relay’s adjustable range must match the motor’s rated current.
- Trip Class:
- Class 10 for normal starting conditions
- Class 20 or 30 for high-inertia loads
- Class 20E for enhanced electronic protection
- Operating Type: Thermal for standard applications; electronic for precision and advanced diagnostics.
- Mounting Compatibility: Contactor-mounted, direct, or independent mounting based on panel design.
- Reset Type: Manual reset for safety-critical systems; auto reset where controlled restart is acceptable.
By aligning these factors with the application’s duty cycle and operating environment, engineers can ensure optimal motor protection and system reliability.
FAQs
1. What is the primary function of an overload relay?
It protects motors from overheating caused by sustained overcurrent conditions.
2. Can overload relays protect against short circuits?
No. Short-circuit protection is handled by fuses or circuit breakers; overload relays address thermal overloads.
3. Which trip class is commonly used in industrial motors?
Class 10 is common, but Class 20 or 30 is used for high-inertia loads.
4. Where can I buy overload relays online?
You can easily purchase overload relays from Eleczo, which offers genuine products from top brands with competitive pricing. For any business inquiries, you can reach their sales team at sales@eleczo.com or call +91 9090903837.
5. Are electronic overload relays better than thermal ones?
They offer higher accuracy and advanced features, but thermal relays remain reliable for many applications.
6. Can one relay be used for different motors?
Only if the motor current ratings fall within the relay’s adjustable range.
7. Where are overload relays typically installed?
They are usually installed with contactors in motor starters or control panels.
8. How can I get an overload relay price list or catalogue?
You can find updated price lists, catalogues, and technical datasheets directly on Eleczo’s website, covering multiple brands and models. For customized quotes or bulk pricing, contact sales@eleczo.com or call +91 9090903837.
Conclusion
Overload relays remain a cornerstone of industrial motor protection in India. From thermal solutions used in standard panels to advanced electronic relays deployed in automated systems, the right selection ensures motor safety, operational continuity, and compliance with engineering best practices. By choosing proven models from trusted brands and sourcing them through reliable platforms like Eleczo, industries can build motor control systems that are both robust and future-ready.
