ABB TA25DU-5.0M Thermal Overload Relay

Pedido nº.: 1SAZ211201R2035

TA25DU-5.0M is a 3-phase bimetallic relé de sobrecarga térmica in the TA25DU série. The M variant is designed for AX series contatores (non‑M versions fit A series contactors). It provides motor overload and phase failure protection.

✅ Core Technical Parameters

Faixa de corrente ajustável: 3.5 ~ 5.0 UM

Classe de viagem: 10UM (standard motor protection)

Rated main circuit voltage: CA 690V / CC 440 V

Poloneses: 3-proteção de poste

Contatos auxiliares: 1NÃO + 1NC (one changeover contact)

Modo de reinicialização: Manual / Automatic reset selectable

Funções integradas: Compensação de temperatura, proteção contra falha de fase, botão de teste, STOP function, indicação de viagem, mecanismo sem desarme

Compatible contactors: AX09, AX12, AX18, AX25 (direct plug-in mounting)

Montagem autônoma: Requires separate mounting base as an accessory

📌 Type Code Definition

ENFRENTANDO: Relé de sobrecarga térmica

25: Frame rated current 25A

DE: Universal bimetallic type

5.0: Maximum setting current 5A

M: Version for AX contactors (differentiated from older TA25DU-5.0 for A contactors)

📋 Typical Applications

Protection for 0.75~2.2kW 3-phase asynchronous motors (380V), applied on machine tools, fãs, bombas de água, conveyors and compressors. It forms a motor starter circuit together with ABB AX contactors.

⚠️ Seleção & Diretrizes de Substituição

1. Substituição da mesma série: TA25DU-5.0 (older version for A contactors; pin layout differs and cannot be directly interchanged)
2. Alternativas domésticas: Delicioso, Chint thermal relays with 3.5–5A range (verify contact configuration, trip class and mounting base)
3. Coordenação: Short-circuit protection shall be implemented with fuses or circuit breakers. This relay only provides overload & proteção contra falha de fase, not short-circuit protection.

📎 Auxiliary Contact Ratings (AC-15)

400V: NC 0.75A, NO 0.37A

240V: NC 3A, NO 1.2A

120V: NC 3A, NO 1.5A

Operating Principle of ABB TA25DU Bimetallic Thermal Overload Relays

Princípio fundamental: Thermal effect of electric current + differential bending of bimetallic strips; inverse-time overload & proteção contra falha de fase. It only works with contactors for motor overload protection and cannot protect against short circuits.

1. Basic 3-phase Structure

Each phase is equipped with: heating element + tira bimetálica. Additional components: differential slide plate, temperature compensation strip, quick-trip mechanism, 1Contatos auxiliares NO+1NC (95/96 NC, 97/98 NÃO), setting knob, reset mechanism and test button.

Tira bimetálica: Two metals with different thermal expansion coefficients bonded together; it bends toward the lower-expansion side when heated.

2. Operação normal

Three-phase current equals the set value. Heat generation is low, and the bimetallic strip only bends slightly, not enough to trigger the trip mechanism. O 95-96 NC contact remains closed, the contactor coil stays energized, e o motor funciona normalmente.

3. Proteção contra sobrecarga (Inverse-time Characteristic)

Sustained motor overload → current exceeds setting → heating element keeps rising in temperature, and the bimetallic strip bends further with accumulated heat.

Once the deformation threshold is reached, the quick-trip mechanism releases, o 95-96 NC contact opens, the ABB contactor coil de-energizes, main contacts break and the motor stops.

Recurso: Característica de tempo inverso: Higher overload current leads to faster tripping. Short starting inrush current will not cause false tripping (Classe de viagem 10A, standard rating for TA25DU series), simulating the thermal inertia of motor windings.

4. Falha de Fase (Perda de Fase) Proteção (Built-in Differential Mechanism on TA25DU)

When three-phase current is unbalanced or one phase is lost:

The open phase carries nearly zero current; its bimetallic strip cools down and springs back.

The other two phases draw much higher current, and their bimetallic strips keep bending.

The differential slide plate amplifies the deformation difference, triggering tripping much faster than regular balanced overload protection. This prevents motor burnout due to phase loss, a standard feature on ABB DU-series thermal relays.

1) Direct Cross-Brand Equivalent (TA25DU-5.0M, 3.5~5A)

2) Full Series Cross Reference Table (TA25DU-M vs Competitors)

Papel 3: Extended Frame Sizes (TAxxDU-M Series)

TA42DU-M: For AX40~AX50 contactors, 25～42A

TA75DU-M: For AX65~AX80 contactors, 25～75A

TA80DU / TA110DU / TA200DU: Modelos de alta corrente (90～200A)

Papel 4: Field Replacement Notes

1. Non-interchangeable base: TA25DU-M only plugs onto AX contactors; older TA25DU fits A contactors. Mismatched mounting will cause loose connection and overheating.
2. Strictly match current range: Select relays with fully overlapping setting ranges; never use higher current ratings to replace lower ones.
3. Proteção contra falha de fase: TA25DU has built-in differential phase-loss protection. Siemens 3RU and Schneider LRD also include this function; confirm this feature before purchasing low-cost domestic models.
4. Modo de reinicialização: Keep manual/automatic reset consistent with the original unit to avoid unintended auto-restart for unattended equipment.

Papel 5: Simplest Replacement Plan for TA25DU-5.0M

Import alternatives: Schneider LRD07C, Siemens 3RU6116-1FB0

Alternativas domésticas: Chint NR2-25/Z 5, Delixi CDR6-25 5

OEM same-model replacement: TA25DU-5.0M (Número do pedido. 1SAZ211201R2035)