TA75DU-42 overload relay: current setting, trip class and contactor coordination
The TA75DU-42 is a three-pole thermal overload relay for motor protection. ABB’s technical catalogue lists a 29–42 A setting range and class 10A for order code 1SAZ321201R1003. The relay is phase-loss sensitive and includes one normally open and one normally closed auxiliary contact. These are relay-family characteristics; confirm mounting and coordination requirements for the exact contactor and starter assembly.
Key technical data
| Technical item | Verified value / selection note |
|---|---|
| ABB order code | 1SAZ321201R1003 |
| Type designation | TA75DU-42 |
| Adjustable setting range | 29–42 A |
| Trip class | 10A |
| Power poles | Three-pole thermal overload relay |
| Auxiliary contacts | 1 NO + 1 NC, electrically isolated |
| Protection functions | Motor overload and phase-loss sensitivity |
| Reset and indication | Manual/automatic reset selection; front TEST/STOP and trip indication |
The values above are intended to identify the listed version and support an initial technical review. Confirm applicable standards, rating conditions, installed accessories and the current ABB documentation for the serial number or revision before design approval, replacement or commissioning.
Application and engineering focus
Set the relay to the motor nameplate current within its adjustment range and in accordance with the selected wiring arrangement. Do not raise the setting to mask repeated trips. Investigate actual load, phase imbalance, cooling, start duration, mechanical friction and supply quality. Class 10A and the selected reset mode affect trip and restart behavior, so align them with the motor’s thermal limits and the machine’s safety and process requirements.
Configuration, compatibility and related references
Confirm direct mounting or the appropriate adapter, the contactor frame, terminal orientation and starter combination. Check the short-circuit protective device separately; an overload relay does not provide short-circuit protection. Coordinate fuse or breaker type and rating using ABB’s documented coordination data. Wire the NC trip contact into the control circuit as designed and use the NO contact for status only if the control logic supports it.
The related designations below are comparison references, not automatic substitutes. Confirm the complete type code, order number, interface, ratings and revision against the approved application before selecting an alternative.
- TA75DU-32
- TA75DU-52
- TA75DU-63
Installation and commissioning checks
Isolate power before fitting or adjusting. Verify all three phases pass through the sensing path and that auxiliary terminals 95–96/97–98 match the control schematic. Select manual or automatic reset deliberately, then test the stop, test and trip functions during commissioning. Record the motor full-load current, relay setting, control response and coordinated protective-device combination for maintenance.
During commissioning, verify the nameplate, configuration, wiring and diagnostics before enabling normal operation. Test the relevant signal path or protection response end to end under controlled conditions. Record settings and as-left measurements, and investigate abnormal values at the sensor, load, wiring or system configuration before replacing components.
Ordering, replacement and application information
For a quotation or replacement review, provide the complete designation 1SAZ321201R1003 TA75DU42, ABB order code where available, serial or hardware revision, quantity, installation environment, connected equipment, interface requirements and target delivery date. Include a clear rating-label photograph and relevant wiring, loop or panel drawing when possible.
Ask the supplier to confirm the exact configuration, accessories, revision and any approved successor in writing. Do not select solely from a family name or product photograph. For safety, grid-protection, medium-voltage or regulated applications, obtain review by the responsible qualified engineer and follow local codes and the manufacturer’s instructions.
