The GEC Alsthom TAH 1111 (Part Number 25744D13 / 30950164) is a specialized “Tropic” grade thermal protection relay designed to safeguard AC motors and electrical equipment against sustained overloads. The “Tropic” designation indicates that the internal components and insulation are specially treated to resist high humidity, fungal growth, and corrosive atmospheres common in equatorial or marine environments. This electromechanical relay operates on the bimetallic principle, providing a reliable inverse-time characteristic that mimics the heating curve of the protected motor.

Product Datasheet & Technical Specifications

The TAH series is built for rugged environmental endurance:

• Model Number: TAH 1111
• Part Number: 25744D13 / 30950164
• Protection Type: Thermal Overload (Device Code 49)
• Phase Configuration: Typically 3-phase monitoring (3-pole)
• Adjustment Range: Field-adjustable current settings (e.g., 0.6x to 1.0x of rated current)
• Resetting: Manual or Automatic reset options (selectable via internal toggle)
• Contacts: 1 NO (Normally Open) + 1 NC (Normally Closed) auxiliary contacts
• Environment: “Tropic” Proofed (high humidity and fungus resistant)
• Case Style: Modular drawout or flush-mount square case

 

Country of Origin

This protection relay was manufactured in France (at the L’Isle d’Abeau or Saint-Ouen facilities), representing the high-quality French engineering standards of the GEC Alsthom / Alstom group.

 

Application Fields

The TAH 1111 is primarily found in heavy industrial sectors operating in challenging climates:

• Mining & Minerals: Protecting conveyor and crusher motors in dusty, humid tropical mines.
• Marine & Offshore: Managing engine room ventilation fans and pump motors on ships and oil rigs.
• Water Treatment: Safeguarding submersible pumps in high-humidity pumping stations.
• Sugar Refineries: Operating in high-temperature, high-moisture processing areas.
• Chemical Plants: Protecting specialized agitator motors in corrosive coastal environments.

 

Product Instructions & Technical Notes

When installing the GEC Alsthom TAH 1111, ensure the current setting dial is precisely aligned with the Full Load Amps (FLA) of the motor as shown on its nameplate. Because this is a thermal relay, its operation is affected by the ambient temperature; if the relay is located in a significantly cooler or hotter environment than the motor, a compensation factor must be applied. For “Tropic” versions, ensure the cable entry points are properly sealed with gaskets to maintain the moisture-resistant integrity of the housing. Periodically test the trip mechanism by using the “Test” lever (usually located under a small cover) to verify that the auxiliary contacts switch correctly.

 

Q&A – Frequently Asked Questions

Q1: What exactly does “Tropic” protection mean for this relay? A: It means the copper coils are vacuum-impregnated with specialized varnish and the mechanical parts are treated with anti-fungal coatings to prevent degradation in environments with >90% humidity.

Q2: Can this relay protect against a short circuit? A: No. The TAH 1111 is a thermal overload relay (Device 49). It is designed for “slow” faults like overloads. It must be used in conjunction with fuses or a magnetic circuit breaker for “fast” short-circuit protection.

Q3: How do I change it from Manual to Auto reset? A: There is typically a small blue or black slider/screw located on the front or side of the internal module. Switching it to ‘A’ allows the relay to reset once the bimetal cools down, while ‘M’ requires an operator to push the reset button.

Q4: Is the 25744D13 part number compatible with Alstom units? A: Yes, GEC Alsthom evolved into Alstom. The 25744D13 is a standard manufacturing code that remained consistent across both brands for this specific hardware revision.

 

Similar Model Recommendations

1. GEC Alsthom TAH 1112 (Higher current range variant)
2. GEC Alsthom thermal relay series (standard non-tropic versions)
3. Alstom MiCOM P111 (Modern digital replacement for motor protection)
4. Telemecanique LR2 series (Industrial thermal overload alternative)
5. GEC Alsthom MVAJ (Auxiliary relays often used in the same trip circuit)