3RN2012-1BW31 | Siemens Sirius 3RN2 Thermistor Motor Protection Relay Standard Evaluation 22.5 mm, 2 C/O, 24 V – 240 V AC/DC, Manual/Auto/Remote Reset – Siemens

Name: 3RN2012-1BW31 | Siemens Sirius 3RN2 Thermistor Motor Protection Relay Standard Evaluation 22.5 mm, 2 C/O, 24 V - 240 V AC/DC, Manual/Auto/Remote Reset - Siemens - myelectric.in
Brand: Siemens
SKU: 3RN2012-1BW31
Price: 38577.90 INR
Availability: InStock

SKU: 3RN2012-1BW31

Original price was: ₹83,865.00.Current price is: ₹38,577.90. Excl. GST

In stock

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The Siemens 3RN2012-1BW31 is an overload relay, engineered for motor control and switching in demanding Indian and international installations. Key ratings include 24V AC. Buy the 3RN2012-1BW31 | Siemens Sirius 3RN2 Thermistor Motor Protection Relay Standard Evaluation 22.5 mm, 2 C/O, 24 V – 240 V AC/DC, Manual/Auto/Remote Reset 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	3RN2012-1BW31
Category	Overload Relay
Contact Configuration	2 CO (Changeover)
Voltage Rating	24V AC
Phase-Loss Sensitivity	Yes — differential bimetal mechanism
Reset Mode	Manual / Automatic (selectable)
Auxiliary Contacts	1 NO + 1 NC
Mounting	Direct mounting on matching contactor
Rated Frequency	50/60 Hz
Standard	IEC 60947-4-1 / IS 13947-4-1
Certifications	BIS certified, CE, cULus (select models)

⚡ Key Features

Bimetal thermal element with phase-loss sensitivity — independently monitors each phase; trips if any phase carries more than ~115% of the set current, or on complete phase failure.
Normally open (NO) and normally closed (NC) auxiliary contacts built in — NO contact wired to motor run indicator; NC contact wired to PLC fault input or motor starter stop circuit.
Manual/automatic reset selectable — set to manual for attended machinery requiring operator acknowledgement; auto-reset for unattended remote installations.
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 2 CO (Changeover) contact configuration on the 3RN2012-1BW31 mean?

A: CO (Change Over) contacts switch between two circuits — the common terminal connects to either NO or NC depending on the device state. Used for dual-purpose indication or reversing circuits.

Q: Does the 3RN2012-1BW31 provide single-phase (phase loss) protection?

A: Siemens thermal overload relays include single-phase sensitivity: if one phase is lost, the remaining phases carry higher current, causing the bimetal to heat and trip within the specified time. For critical motors, add a dedicated phase-loss relay for faster response independent of load — overload relay phase-loss protection is load-dependent and may take minutes to trip at light load.

Q: How do I set the 3RN2012-1BW31 to protect a motor without causing nuisance trips on starting?

A: Set the thermal overload dial to the motor’s nameplate full-load current (FLC). For star-delta starters, set the overload relay to 58% of motor FLC (line current in delta = FLC × 0.58). Allow 10 trips for the relay’s thermal memory to stabilise before adjusting the setting.

Q: What is the difference between an Overload Relay and a standard MCB — and why use the 3RN2012-1BW31?

A: A standard MCB protects against overload and short-circuit only. An Overload Relay provides thermal overload protection calibrated to motor FLC, protecting the motor from sustained overloads that would destroy windings before a standard MCB trips. Choose the 3RN2012-1BW31 when the application specifically requires overload relay characteristics.