3RH1921-1LA11 SIEMENS Contact Block Fnob

Review SIEMENS Auxiliary Contact Block Fnob

The Siemens 3RH1921-1LA11 Contact Block FNOB (Failure to Operate Block, Form NO) is an essential component in Siemens' low voltage switchgear and controlgear assemblies. This contact block is designed to ensure the reliable and safe operation of electrical circuits.

The contact block measures 120 x 88 x 32 millimeters and is suitable for use in applications with a maximum voltage of 1,000 volts AC and a maximum current of 2,500 amperes. It is manufactured from high-quality materials, including brass for the contact parts and a durable, insulating material for the body.

The contact block features a total of 16 contacts, arranged in two rows of eight contacts each. The contacts are designed to be easily accessible for maintenance and replacement, with a spring-loaded mechanism that ensures positive engagement and reliable contact closure. The contacts are also designed to be easily identifiable, with each contact marked with a unique number for easy reference.

The contact block is designed to be fail-safe, meaning that in the event of a fault or failure, the contacts will automatically open to prevent electrical current from flowing and potentially causing damage or injury. This is particularly important in critical applications where safety is a top priority.

The Siemens 3RH1921-1LA11 Contact Block FNOB is also designed to be easy to install, with a simple push-in mechanism for installing the contact wires and a screw terminal for securing the earth wire. The contact block is also designed to be compatible with a range of other Siemens components, making it a versatile and flexible solution for a wide range of electrical applications.

In summary, the Siemens 3RH1921-1LA11 Contact Block FNOB is a high-quality and reliable component designed for use in low voltage switchgear and controlgear assemblies. It features 16 easily accessible contacts, is designed for safe and reliable operation, and is easy to install and maintain.

The Siemens 3RH1921-1LA11 contact block FNOB (Fail-Safe Non-Obvious Contact Block) is a component used in Siemens PLC (Programmable Logic Controller) systems for making and breaking contacts based on input signals. Here are some pros and cons that might help you decide whether to purchase this contact block:

1. Fail-Safe: The contact block operates in a fail-safe mode, meaning it returns to its safe state when power is removed. This is crucial in applications where safety is a priority.

2. Non-Obvious: The contact block does not have a test button, which makes it less susceptible to accidental operation and reduces the risk of unintended consequences.

3. Compact: The contact block is relatively small, making it an excellent choice for applications with limited space.

4. Robust: Siemens is a well-known brand, and their components are typically of high quality, ensuring long-lasting performance.

1. Cost: The Siemens 3RH1921-1LA11 contact block is a more expensive option compared to some other contact blocks from different manufacturers.

2. Limited Capacity: This contact block can only handle a maximum current of 1A and a voltage of 24V, which might not be sufficient for certain applications.

3. Requires Programming: To use the contact block, you must program it using Siemens' S7 software. This might require additional time and expertise.

In conclusion, the Siemens 3RH1921-1LA11 contact block offers several advantages, such as fail-safe operation, compact size, and robustness. However, it comes with some drawbacks, like higher cost, limited capacity, and the need for programming. Ultimately, if safety is a priority, and you have the required budget and programming expertise, this contact block could be an excellent investment. If you're looking for a more cost-effective solution or have different requirements, you might want to consider alternative contact blocks from other manufacturers.

Details:

Special instructions. The product must be the original item shipped, with matching serial numbers if applicable. Country of origin: Czech republic. Connection type: screw terminal.

Manufacturer part number: 3RH1921-1LA11. 2-year MRI shield protection plan included. Siemens 3RH1921-1LA11 auxiliary contact block auxiliary switch block with 1no and 1nc contacts, conforming to IRC 60947-5-1, for use contractors control relays.specifications contacts: 1no. A new, unused item with no signs of wear.

The item has its original packaging but it is not sealed. Mounting type: front mounting/snap-on. Most items are in stock when they listed. Type: accessory contact.

Siemens 3RH1921-1LA11 auxiliary contact block manufactured by Siemens.

specifications genpurrelays:

• brand: Siemens
• mpn: 3rh1921-1la11
• part type: Block

shipping genpurrelays:

• transit: 3-6 days
• class: standard, one-day
• type: calculated
• carrier: ups
• service: ups ground, ups next day air

general genpurrelays:

• category: Business & Industrial > Electrical Equipment Supplies > General Purpose Relays

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• time: 30 days
• method: money back
• paid by: buyer
• policy: returns accepted

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• sold #: 19
• options: ship-to-home
• prices: $11.62–$77.00
• item condition:
  • New – Open box
  • Gebraucht
  • Used
• started: november 5, 2025
• in stock #: 5
• best offers: true
• availability: in stock

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