3RH21311BG40 | Contactor relay, 3 NO + 1 NC, 125 V DC, Size S00, screw terminal – Siemens

Name: Siemens 3RH21311BG40 Contactor Relay, 3NO+1NC, 125VDC
Brand: Siemens
SKU: 3RH21311BG40
Price: 2065.40 INR
Availability: InStock

SKU: 3RH21311BG40

Original price was: ₹4,490.00.Current price is: ₹2,065.40. Excl. GST

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The Siemens 3RH21311BG40 is a contactor, engineered for motor control and switching in demanding Indian and international installations. Key ratings include 125V AC. Buy the 3RH21311BG40 | Contactor relay, 3 NO + 1 NC, 125 V DC, Size S00, screw terminal online at myelectric.in with GST invoice, genuine-product assurance, and fast delivery across India — bulk and worldwide export enquiries welcome.

📋 Technical Specifications

Parameter	Value
Brand	Siemens
Part Number / SKU	3RH21311BG40
Category	Contactor
Contact Configuration	3 NO + 1 NC
Voltage Rating	125V AC
Utilisation Category	AC-3 (motor duty) / AC-1 (resistive)
Rated Frequency	50/60 Hz
Coil Operating Range	0.8–1.1 × rated coil voltage (Uc)
Mounting	35mm DIN rail or screw fixing
Standard	IEC 60947-4-1 / IS 13947-4-1
Certifications	BIS certified, CE, cULus (select models)

⚡ Key Features

Manufactured to IEC 60947-4-1 / IS 13947-4-1 — complies with the applicable Indian BIS and IEC international standards for this product category.
BIS certified, CE, cULus (select models) — meets Indian regulatory requirements for use in government, commercial, and industrial electrical installations.
Genuine authorised Siemens product — sourced directly from the official distribution network with full manufacturer traceability and warranty.
GST invoice provided for India orders — valid for corporate procurement, government project orders, and public tender supply via myelectric.in.
Worldwide export available — UAE, Singapore, UK, USA, Sri Lanka & more. Contact +91 94814 00316 for bulk pricing and international shipping.

❓ Frequently Asked Questions

Q: What does the 3 NO + 1 NC contact configuration on the 3RH21311BG40 mean?

A: This device has both Normally Open (NO) and Normally Closed (NC) contacts. NO contacts close when the device operates (energised/tripped); NC contacts open. This allows both start-interlock and stop-interlock circuits from a single device.

Q: Can multiple 3RH21311BG40 contactors be wired for star-delta starting?

A: Yes. Star-delta starters use three contactors: main (KM1), star (KM2), and delta (KM3). The Siemens contactor series supports mechanical and electrical interlocking accessories that prevent simultaneous energisation of star and delta contactors — critical for safety. Ensure all three contactors are rated correctly for the motor FLC and star-delta transition current.

Q: What is the electrical and mechanical life of the 3RH21311BG40?

A: Siemens contactors are rated for millions of operations: typically 10–30 million mechanical operations and 1–3 million electrical operations at rated current and voltage (AC-3 duty). High-frequency switching applications (>10 operations/hour) require checking the specific thermal capacity of the contactor for continuous duty without overheating.

Q: Can the 3RH21311BG40 be used for reversing duty (forward/reverse motor control)?

A: Contactors used for reversing must be wired with two contactors interlocked so only one can energise at a time. The Siemens series provides mechanical interlock kits that physically prevent both contactors from closing simultaneously — mandatory for reversing and brake applications to prevent phase-to-phase short circuits.