The Siemens 3WT8121-6UA34-5AB2 is a SENTRON 3WT8 withdrawable air circuit breaker (ACB) designed for high-current low-voltage power distribution and protection applications. It is a 3-pole, Size 1 circuit breaker with a rated current of 1250 A and rated voltage up to 500 V AC at 50/60 Hz. The breaker has a specified ultimate short-circuit breaking capacity (Icu) of 66 kA at 500 V. Siemens' current Industry Mall listing confirms the exact MLFB and configuration.
The 3WT8121-6UA34-5AB2 combines a withdrawable construction with a guide frame, making it suitable for switchboards where convenient inspection, servicing and replacement are important. The withdrawable design allows the breaker to be moved between operating and withdrawn positions without completely removing the unit from the switchboard arrangement.
This model is equipped with the ETU37WT LSING electronic overcurrent release with display, providing electronic protection functions for suitable overload and fault conditions. The exact protection settings should be configured according to the electrical system and coordination study. Siemens documentation identifies the ETU37WT configuration for this 3WT8 product family.
The breaker includes a motorized/manual operating mechanism with stored-energy memory, along with control equipment for 220–240 V AC / 220–250 V DC motor and electrical charging. It also includes a 220–250 V DC activation solenoid and a shunt release F/F2 rated for 220–240 V AC and 220–250 V DC.
Safety and status-monitoring functions include a mechanical lockout device, tripped signaling switch, tripped indicators, auxiliary current switches and a shutter system with sealing provisions. These features are useful in industrial switchgear where secure operation, breaker status indication and controlled access are important.
| Specification | Details |
|---|---|
| Product | Siemens 3WT8121-6UA34-5AB2 |
| Product Type | Withdrawable Air Circuit Breaker |
| Series | SENTRON 3WT8 |
| Configuration | 3-Pole |
| Frame Size | Size 1 |
| Rated Current (In) | 1250 A |
| Rated Voltage | Up to 500 V AC |
| Frequency | 50/60 Hz |
| Breaking Capacity (Icu) | 66 kA at 500 V |
| Short-Time Current Strength (Icw) | 66 kA/S |
| Overcurrent Release | ETU37WT LSING with display |
| Operating Mechanism | Motorized/manual with memory |
| Design | Withdrawable with guide frame |
| Motor/Electrical Charging Voltage | 220–240 V AC, 220–250 V DC |
| Activation Solenoid | 220–250 V DC |
| Shunt Release | F, F2; 220–240 V AC / 220–250 V DC |
| Auxiliary Current Switch | 2 NC + 2 NO |
| Standard | IEC 60947-2 |
The technical information above is based on Siemens' current product listing and available product documentation for 3WT8121-6UA34-5AB2.
The Siemens 3WT8121-6UA34-5AB2 1250A 3-pole withdrawable ACB can be considered for:
The 1250 A rated current makes the 3WT8121-6UA34-5AB2 suitable for high-current low-voltage distribution applications where substantial electrical loads need reliable circuit protection and switching.
Its 66 kA Icu at 500 V AC provides a high level of short-circuit interruption capability for suitable installations. The actual prospective fault current at the installation point should always be evaluated to verify that the breaker is correctly selected.
The withdrawable design with guide frame is particularly useful in switchboards where maintenance access and equipment replacement are important. It can help reduce service-related downtime because the breaker can be withdrawn from the connected position as part of the applicable switchgear operating procedure.
The ETU37WT LSING electronic overcurrent release with display provides electronic protection and monitoring functions suitable for the configured breaker. This supports more controlled protection settings compared with a purely thermal-magnetic protective device.
The motorized/manual operating mechanism with memory provides flexible breaker operation for suitable electrical control schemes. The associated motor and electrical charging circuit is specified for 220–240 V AC or 220–250 V DC, while the activation solenoid is rated 220–250 V DC.
The integrated mechanical lockout, tripped signaling and indication functions provide useful operational and safety features for industrial switchgear. They help operators and maintenance personnel identify breaker status and support controlled operating procedures.
The 2 NC + 2 NO auxiliary current switch arrangement, shutter system and door sealing frame provide additional functionality for switchboard integration and operational control.
For panel builders, EPC companies, OEMs, electrical contractors, system integrators and industrial maintenance teams, the Siemens 3WT8121-6UA34-5AB2 offers a high-current withdrawable ACB solution for demanding power-distribution applications.
The Siemens 1250A 3P 66kA withdrawable ACB can be considered for suitable projects across Faridabad, Delhi NCR, Noida, Gurgaon/Gurugram, Ghaziabad, Punjab, Mumbai, Pune, Ahmedabad, Hyderabad, Bengaluru/Bangalore, Chennai, Kolkata, Jaipur, Chandigarh, Ludhiana and other major industrial and commercial locations across India.
Before installation or replacement, verify the 3WT8 breaker configuration, guide-frame compatibility, rated voltage, fault level, ETU settings, control voltages and switchboard connection arrangement.
SB Smart supplies Siemens circuit breakers, switchgear and industrial electrical products for OEMs, EPC contractors, panel builders, electrical contractors, system integrators and industrial maintenance teams across India.
The Siemens 3WT8121-6UA34-5AB2 1250A 3-pole withdrawable ACB is suitable for customers looking for high-capacity Siemens circuit protection for main distribution boards, industrial switchboards, generator systems, infrastructure projects and critical power applications.
SB Smart supports Siemens product sourcing across Faridabad, Delhi NCR, Noida, Gurgaon/Gurugram, Mumbai, Pune, Ahmedabad, Hyderabad, Bengaluru/Bangalore, Chennai, Kolkata, Chandigarh, Ludhiana and other major Indian industrial markets.
1. What is Siemens 3WT8121-6UA34-5AB2?
It is a Siemens SENTRON 3WT8 withdrawable Air Circuit Breaker (ACB) with a 3-pole configuration and 1250 A rated current.
2. What is the breaking capacity?
The specified Icu is 66 kA at 500 V AC.
3. What is the rated current?
The breaker has a rated current of 1250 A.
4. What is the rated voltage?
The breaker is specified for applications up to 500 V AC at 50/60 Hz.
5. What type of trip unit does it use?
It uses the ETU37WT LSING electronic overcurrent release with display.
6. Is this breaker withdrawable?
Yes. The product is a withdrawable circuit breaker supplied with a guide frame.
7. What control voltage is used for the motor mechanism?
The motor and electrical charging circuit is specified for 220–240 V AC or 220–250 V DC.
8. What safety and indication features are included?
The configuration includes a mechanical lockout device, tripped signaling switch, tripped indicators, auxiliary contacts, shutter and door sealing frame.
| Parameter | Specification |
|---|---|
| Product Series | Siemens SENTRON 3WT8 |
| Part Number | 3WT8121-6UA34-5AB2 |
| Product Type | Air Circuit Breaker (ACB) |
| Number of Poles | 3 Pole |
| Rated Current | 1250A |
| Rated Voltage | Up to 500V AC |
| Breaking Capacity (Icu) | 66kA @ 500V AC |
| Protection Unit | ETU37WT LSING |
| Protection Functions | Overload, Short Circuit, Earth Fault |
| Type | Withdrawable / Draw-out |
| Frequency | 50/60 Hz |
| Mounting Type | Fixed base with draw-out mechanism |
| Standard | IEC 60947-2 |
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