Product Description

🛍️ Siemens 3RH2131-1KB40 SIRIUS Coupling Contactor Relay – 24V DC, 3NO+1NC

The Siemens 3RH2131-1KB40 is a specialized SIRIUS 3RH2 coupling contactor relay engineered specifically for direct interfacing between low-power PLC digital outputs and high-power industrial control circuits. Built in a compact Size S00 frame, it features a 3 Normally Open (3NO) + 1 Normally Closed (1NC) contact configuration and operates on a low-power 24V DC control coil (2.8W) with an integrated suppressor diode to absorb coil inductive spikes and protect sensitive electronic outputs.

Key Features & Technical Details

• Direct PLC Compatibility: Low coil power consumption (approx. 2.8W) allows direct switching via PLC transistor outputs without needing intermediate amplification relays.

• Integrated Suppressor Diode: Factory-equipped with a built-in suppressor diode to damp opening voltage surges and safeguard upstream PLC modules.

• 3NO + 1NC Contact Configuration: Equipped with 3 Normally Open and 1 Normally Closed auxiliary poles for versatile signal switching, interlocking, and status feedback.

• Wide Operating Range (0.7–1.25 × Us): Highly tolerant to control voltage fluctuations, ensuring reliable operation under varying power supply conditions.

• Compact Size S00 Frame: Saves valuable space inside automation cabinets, Motor Control Centers (MCCs), and distributed I/O control boxes.

• Vibration-Proof Screw Terminals: Features durable screw connection technology for secure, maintenance-free conductor clamping.

• Extreme Mechanical Durability: Rated for a service life of up to 30 million operating cycles, ensuring long-term operational reliability in continuous-duty applications.

Ideal Applications

• PLC Output Interfacing & Signal Isolation Buffers

• Sensor-to-Contactor Interfacing & Control Logic

• Motor Control Centers (MCC) & Automation Panels

• Machine Tools, Packaging Machinery & Conveyor Control Systems

• Safety Interlocking & Process Automation Cabinets

❓ Frequently Asked Questions (FAQs)

Q1: What is a "coupling contactor relay" and how does it differ from a standard contactor relay?

A: A coupling contactor relay is optimized with a low-power coil (2.8W) and integrated coil surge suppression (suppressor diode), allowing it to be connected directly to a PLC's digital output without damaging the output electronics or requiring external interface cards.

Q2: What is the control coil voltage and contact arrangement for the 3RH2131-1KB40?

A: It operates on a 24V DC coil and provides a 3NO + 1NC (3 Normally Open + 1 Normally Closed) auxiliary contact arrangement.

Q3: Does this coupling relay require an external surge suppressor for the coil?

A: No, this model comes with an integrated suppressor diode built directly into the coil circuit to clamp voltage peaks when de-energized.

Q4: How is the Siemens 3RH2131-1KB40 mounted inside a control cabinet?

A: It supports convenient dual-mounting options, snapping easily onto standard 35mm DIN rail or mounting directly via panel screws.

🔗 Compatible Accessories & Cross-Selling Products

• Siemens 3RT201 Series Power Contactors (Size S00): Matching Size S00 power contactors for switching 3-phase motor loads driven by PLC/coupling outputs.

• Siemens SITOP 24V DC Power Supplies: Industrial-grade 24V power supply units ideal for supplying smooth DC control voltage to PLCs and coupling relays.

• Siemens 3RV2 Motor Starter Protectors: Compact circuit breakers for short-circuit and overload protection in the same control layout.