Siemens 3RT6028-1AG20 3RT60 Series AC Contactor 110VAC 38A 3NO

The Siemens 3RT6028-1AG20, a robust component within the 3RT60 series AC contactor lineup, stands as a powerful solution for demanding industrial applications. This contactor boasts a 110VAC coil voltage, a substantial 38A current rating, and a configuration of three normally open (3NO) poles, making it ideal for switching high-power electrical loads. Its inherent reliability, coupled with Siemens' renowned engineering, positions it as a go-to choice for critical control circuits in various industrial sectors. Key advantages include its compact design, facilitating space-efficient panel building, and its adherence to stringent international safety and performance standards.

Product Specifications

| Feature              | Specification                               |

| :------------------- | :------------------------------------------ |

| Manufacturer         | Siemens                                     |

| Series               | 3RT60                                       |

| Product Number       | 3RT6028-1AG20                               |

| Type                 | AC Contactor                                |

| Coil Voltage         | 110VAC                                      |

| Rated Current (AC-3) | 38A                                         |

| Number of Poles      | 3                                           |

| Contact Configuration| 3 Normally Open (3NO)                       |

| Auxiliary Contacts   | (Typically configurable, check datasheet)     |

| Mounting             | DIN Rail or Screw Mount                     |

| Protection Class     | IP20 (enclosure)                            |

| Operating Temperature| -25°C to +60°C                              |

| Standards            | IEC/EN 60947-4-1, UL, CSA |

Core Features & Market Positioning

The Siemens 3RT6028-1AG20 distinguishes itself through its exceptional durability and consistent performance in harsh industrial environments. As part of the 3RT60 series, it benefits from Siemens' extensive experience in electrical control technology, offering a reliable solution for motor control and power switching. Its market positioning is firmly rooted in providing a high-quality, dependable component that minimizes downtime and ensures operational continuity. The contactor’s robust construction and adherence to international standards like IEC/EN 60947-4-1 give it a competitive edge, assuring users of its suitability for critical infrastructure. Furthermore, its compatibility with a wide range of Siemens control and automation systems enhances its value proposition for integrated solutions.

Key Application Scenarios

The Siemens 3RT6028-1AG20 finds extensive use in applications requiring the reliable switching of AC loads, particularly motor control circuits. Industries such as manufacturing, material handling, HVAC systems, and pump control frequently specify this contactor for its robust 38A rating and 3NO pole configuration. It is a critical component in automated production lines, enabling the start, stop, and reversing of electric motors. Its suitability extends to power distribution panels, where it can be employed for load shedding or as a main disconnect in certain configurations. The 110VAC coil voltage makes it compatible with many standard control power circuits found in North American and international installations.

Practical System Integration Guidance

Integrating the Siemens 3RT6028-1AG20 into an industrial control system is straightforward due to its standardized mounting options and connection terminals. The contactor can be mounted directly onto a standard 35mm DIN rail or secured via screw terminals, offering flexibility in panel design. Wiring the control circuit to the 110VAC coil requires careful attention to polarity and ensuring the power source matches the specified voltage. For power circuit connections, the main terminals are designed to accommodate appropriate gauge wiring for the 38A rating. It is crucial to adhere to local electrical codes and wiring best practices during installation. When used for motor control, it is often paired with overload relays (e.g., Siemens 3UA series) for comprehensive motor protection, typically wired in series with the coil or control circuit.

Operation and Risk Mitigation

Proper operation of the Siemens 3RT6028-1AG20 is paramount for safety and system longevity. The contactor is designed to operate reliably when supplied with its rated 110VAC coil voltage, which energizes the electromagnet, causing the main contacts to close. When the coil voltage is removed, a spring mechanism returns the contacts to their normal (open) state. Risk mitigation involves ensuring the contactor is correctly sized for the load it is switching, preventing overheating and premature failure. Regular inspection for signs of wear, such as pitted contacts or damaged insulation, is recommended. In case of faults, especially those related to coil failure or contact welding, a proper lockout/tagout procedure must be followed before any maintenance or inspection is performed to prevent electrical shock.

Scalability & Long-Term Value

The Siemens 3RT6028-1AG20 offers significant long-term value through its robust design and compatibility within the broader Siemens industrial automation ecosystem. While this specific model is a standalone component, its integration into larger systems can be enhanced by pairing it with Siemens programmable logic controllers (PLCs) or human-machine interfaces (HMIs). This allows for remote operation, status monitoring, and inclusion in sophisticated control strategies. For applications requiring more advanced digital capabilities or IIoT integration, the 3RT60 contactor can serve as a foundational switching element within a modernized control architecture. Its inherent reliability minimizes replacement cycles, contributing to reduced maintenance costs and operational efficiency over the lifespan of the industrial plant.

Frequently Asked Questions (FAQs)

Q1: What is the primary function of the Siemens 3RT6028-1AG20?

This AC contactor is designed for switching electrical power circuits, most commonly used for starting and stopping electric motors. It provides a reliable means to connect or disconnect power to equipment based on control signals.

Its 38A rating makes it suitable for medium to high-power loads in industrial settings. The 110VAC coil voltage dictates the control signal required to activate its switching mechanism.

The 3NO (three normally open) configuration means that when the coil is de-energized, the main power contacts are open, and when energized, they close, allowing current to flow.

Q2: Can the Siemens 3RT6028-1AG20 be used for DC loads?

While primarily designed for AC applications, some contactors can be adapted for DC use with specific considerations. However, for the 3RT6028-1AG20, it's strictly rated for AC loads.

Using it with DC loads can lead to arc-quenching issues and premature contact failure. For DC applications, it's essential to select a contactor specifically designed for direct current.

Always consult the official Siemens datasheet for the 3RT6028-1AG20 to confirm its suitability for any specific load type and voltage. Using it outside its specified application voids warranty and poses safety risks.

Q3: What is the correct way to wire the coil of the Siemens 3RT6028-1AG20?

The Siemens 3RT6028-1AG20 has a coil rated for 110VAC. You connect the 110VAC control power source to the two coil terminals, typically labeled A1 and A2.

Ensure the control voltage precisely matches the 110VAC rating to prevent coil damage or malfunction. Incorrect voltage can cause overheating or failure to energize properly.

Observe proper electrical wiring practices, including insulation, strain relief, and compliance with local electrical codes, for safe and reliable operation.

Q4: How do I select an appropriate overload relay for the 3RT6028-1AG20?

An overload relay protects the motor from excessive current. You typically select an overload relay based on the full-load current (FLC) of the motor being controlled.

The overload relay is usually wired in series with the contactor's power terminals and often has auxiliary contacts that signal a trip to the control system or directly de-energize the contactor coil.

Consult the motor's nameplate and the overload relay manufacturer's selection guide to ensure correct sizing and compatibility with the 3RT6028-1AG20 for effective motor protection.

Q5: What does "38A" signify for this Siemens contactor?

The "38A" rating refers to the maximum continuous current the contactor can safely handle under AC-3 duty conditions. AC-3 duty typically involves starting squirrel cage motors and stopping them.

This rating is crucial for ensuring the contactor does not overheat or fail when carrying the operational current of the connected equipment. It's a key parameter for proper application sizing.

Exceeding the 38A rating, especially for extended periods or frequent switching, can lead to premature wear of the contacts, coil burnout, or even fire hazards.

Q6: Can this contactor be used for frequent switching operations?

The Siemens 3RT6028-1AG20 is built for industrial use and can handle frequent switching, but its lifespan is influenced by the duty cycle and load type. For very high switching frequencies, specialized contactors or solid-state relays might be more suitable.

Siemens contactors are designed with robust contact materials and mechanical endurance. However, extreme switching rates can still accelerate wear, impacting longevity and reliability over time.

Always refer to the specific mechanical and electrical endurance ratings in the product datasheet to determine if it meets the requirements of your high-cycle application.

Q7: What are common failure modes for this type of contactor?

Common failure modes include contact wear or welding due to excessive current or arcing, coil burnout from overvoltage or sustained energization without load, and mechanical issues affecting contact actuation.

If the contactor fails to close, the coil might be damaged or the control voltage incorrect. If it fails to open, contacts may have welded shut, or a mechanical obstruction could be present.

Regular inspection, proper sizing, and adherence to operating conditions are key to preventing these failure modes and ensuring maximum service life for the Siemens 3RT6028-1AG20.

Q8: Is the Siemens 3RT6028-1AG20 compatible with PLC outputs?

Yes, the 110VAC coil of the 3RT6028-1AG20 can be controlled by a PLC output, but usually through an interface relay or a dedicated PLC output module. Standard PLC outputs might not have the current/voltage capacity to directly drive the coil.

You would typically use a PLC digital output to energize a smaller interposing relay, whose contacts then switch the 110VAC to the contactor coil. This protects the PLC and provides the necessary power.

Alternatively, if the PLC output module is rated for 110VAC and sufficient current, direct control might be possible, but always verify the PLC module's specifications against the contactor's coil requirements.

Q9: What are the advantages of using Siemens contactors over other brands?

Siemens contactors, including the 3RT60 series, are known for their high quality, reliability, and long service life, even in demanding industrial environments. They adhere to stringent international standards, ensuring consistent performance.

The brand benefits from extensive research and development, offering innovative features and robust designs. Siemens also provides comprehensive technical support and a wide product portfolio for integrated automation solutions.

Their strong global presence means that replacement parts and technical expertise are generally readily available, minimizing potential downtime for users of their products like the 3RT6028-1AG20.

Q10: How can I check if the Siemens 3RT6028-1AG20 is energized?

You can check if the coil is energized by using a multimeter set to AC voltage to measure between the coil terminals (A1 and A2) – it should read approximately 110VAC.

Observe the physical actuation of the contactor. When energized, you should hear an audible "click" as the electromagnet engages, and if visible, you can often see the armature moving and the contacts closing.

Some contactors have built-in indicator lights, or you can add an auxiliary contact to the contactor wired to an indicator lamp, which will light up when the main contacts are closed and the coil is energized.