ABB TA25DU6.5 Thermal Overload Relay
Overview
The ABB TA25DU6.5 (setting range 4.5-6.5A) is a Type TA thermal overload relay engineered to protect three-phase induction motors from sustained overload and single-phasing conditions. Rated for a setting range of 4.5–6.5 A, it is part of the well-established ABB TA25DU frame size — the smallest in the TA25DU–TA450DU family — and mounts directly beneath ABB A/AE/AL9 through A/AE/AL40 series contactors without any adapter kit. As an electromechanical bimetal device, the TA25DU6.5 delivers dependable, field-proven motor protection at low cost and with virtually no maintenance, making it a staple in motor control centers (MCCs), starter panels, and OEM machine builds across the Gulf region.
Seven Star LLC supplies the ABB TA25DU6.5 thermal overload relay to panel builders, contractors, and industrial end users throughout Oman and the wider GCC as part of its authorized ABB low-voltage products portfolio. Whether you are refurbishing an existing motor control center in Sohar Industrial Estate, commissioning new starter panels for a Muscat utility project, or maintaining rotating equipment in Salalah’s free zone, Seven Star provides genuine ABB TA25DU6.5 relays, along with full traceability and application support.
Measurement and Operating Principle
The TA25DU6.5 is a three-pole thermal overload relay in which the motor’s line current flows directly through three bimetal strips, one per phase. As current rises above the calibrated setting, the bimetals heat and deflect proportionally to the I²t (current-squared-time) thermal load imposed on the motor windings, closely mimicking the actual heating curve of the protected motor. When the deflection reaches a fixed mechanical threshold, the relay trips a snap-action mechanism that opens the auxiliary NC contact (95-96) in the contactor coil circuit and closes the NO signal contact (97-98) for remote alarm or PLC indication, de-energizing the motor before winding insulation damage occurs.
Because the relay is a genuine current-sensing thermal analog rather than a fixed-time device, it inherently provides phase-failure protection per IEC 947-4-1: if one phase is lost, the unbalanced heating of the remaining bimetals accelerates tripping well ahead of the normal single-phase thermal limit, protecting the motor from the negative-sequence heating that phase loss otherwise causes. The relay also incorporates ambient temperature compensation from -25°C to +55°C, so nuisance tripping or under-protection caused by hot switchroom or outdoor enclosure temperatures — a real concern in Oman’s summer ambient conditions — is automatically corrected.
Engineering Design
Mechanically, the ABB TA25DU6.5 is a close-coupled, base-mounted unit designed for direct assembly under ABB A-line contactors up to frame A40, using the contactor’s own mounting rails with no separate bracket. A separate mounting kit (DB25) is available where the relay must be panel-mounted apart from its contactor, for example in remote-trip motor protection schemes. All power and control terminals are accessible from the front of the device, and captive terminal screws with screwdriver guide holes speed panel wiring and reduce dropped-hardware risk during commissioning.
The relay is offered in Trip Class 10 as standard, with a Trip Class 20 variant (TA25DU6.5-20) available for higher-inertia loads that require a longer permissible starting time, such as fans, pumps, and compressors with extended run-up. Reset can be field-selected between manual and automatic operation, and the design is inherently free-tripping — holding the reset button in does not defeat a genuine overload trip, a critical safety feature. A built-in STOP function and manual test button let technicians verify trip and reset operation without removing power from the panel, and a mechanical trip indicator flag provides at-a-glance fault status during troubleshooting.
ABB TA25DU6.5 Key Features
- Setting range 4.5–6.5 A, Trip Class 10 (Class 20 variant available) per IEC 947-4-1
- Three-pole bimetal design with true I²t thermal current sensing for accurate motor overload protection
- Built-in phase-failure and single-phasing protection with accelerated trip response
- Ambient temperature compensation from -25°C to +55°C
- Free-tripping mechanism — reset button cannot defeat a genuine fault trip
- Field-selectable manual or automatic reset, plus integral STOP and manual test functions
- Direct close-coupled mounting to ABB A/AE/AL9–A/AE/AL40 contactors, no adapter required
- Built-in 1 N.O. + 1 N.C. auxiliary contacts for trip alarm and remote indication circuits
Industrial Applications
The ABB TA25DU6.5 is specified wherever small and medium three-phase motors need reliable, low-cost overload protection: pump and fan motor starters, conveyor drives, compressor motor control circuits, HVAC motor starters, and general-purpose machine tool and packaging equipment drives. Its compact footprint and direct contactor mounting make it a default choice for OEM panel builders standardizing on ABB A-line motor starters, while its manual/automatic reset flexibility suits both unattended remote pumping stations and locally supervised production lines.
As an authorized ABB partner, Seven Star LLC supports oil and gas, petrochemical, water and wastewater, power generation, and manufacturing customers across Oman — from Muscat and Sohar to Duqm and Salalah — with genuine TA25DU6.5 relays, spares kitting for MCC refurbishments, and technical guidance on trip class and setting range selection to match actual motor nameplate current and starting duty.
ABB TA25DU6.5 Technical Specifications
| Model | ABB TA25DU6.5 |
| Type | Thermal overload relay, Type TA25DU frame |
| Setting Range | 4.5–6.5 A |
| Trip Class | 10 (Class 20 variant: TA25DU6.5-20) |
| Poles | 3, with ambient temperature compensation |
| Auxiliary Contacts | 1 N.O. (97-98) + 1 N.C. (95-96) |
| Reset Mode | Manual or automatic, field-selectable |
| Ambient Compensation | -25°C to +55°C |
| Mounting | Direct close-coupled to A/AE/AL9–A/AE/AL40 contactors; DB25 kit for separate mounting |
| Standards | IEC 947-4-1, UL File E48139, CSA File LR98336 |
| Manufacturer | ABB |
Request a Quote
Contact Seven Star LLC for pricing on the ABB TA25DU6.5,, lead time, and stock availability on the genuine ABB TA25DU6.5 thermal overload relay in Oman. Our engineering team can also help you select the correct TA25DU setting range and trip class for your specific motor nameplate current and starting profile.
Related Products
ABB is one of the world’s leading technology companies in electrification and automation, recognized for its commitment to innovation, reliability, and energy efficiency. With a history spanning more than a century, ABB delivers high-performance products and systems that help industries operate more intelligently and sustainably.
The company’s expertise covers a wide range of fields including power distribution, process automation, robotics, motion control, and digital solutions for smart manufacturing. ABB’s products are designed to enhance productivity, safety, and operational efficiency while reducing energy consumption and environmental impact.
Seven Star LLC supplies a complete selection of genuine ABB products, including industrial drives, PLCs, contactors, sensors, relays, and automation components, serving clients across oil & gas, energy, marine, and manufacturing sectors.
By combining ABB’s advanced engineering with Seven Star LLC’s trusted sourcing and support, customers gain access to reliable, future-ready industrial solutions built to meet the most demanding standards of modern industries.
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