3RU2126-4FB00-8K | Siemens Sirius 3RU2 Thermal Overload Relay 34 – 40 A, Direct Mounting, Manual Reset, Suitable For S0 Size 3RT Contactor – Siemens

Name: 3RU2126-4FB00-8K | Siemens Sirius 3RU2 Thermal Overload Relay 34 - 40 A, Direct Mounting, Manual Reset, Suitable For S0 Size 3RT Contactor - Siemens - myelectric.in
Brand: Siemens
SKU: 3RU2126-4FB00-8K
Price: 3562.70 INR
Availability: InStock

SKU: 3RU2126-4FB00-8K

Original price was: ₹7,745.00.Current price is: ₹3,562.70. Excl. GST

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📋 Technical Specifications

Parameter	Value
Brand	Siemens
Part Number / SKU	3RU2126-4FB00-8K
Category	Overload Relay
Series / Model	3RT
Current Rating	34–40 A
Standard	IEC 60947-4-1, IS 13947
Certifications	BIS certified, CE, cULus (select models)

⚡ Key Features

Adjustable current range 34–40 A — set to the motor nameplate FLC for accurate overload detection; range covers multiple motor sizes from a single relay model.
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: How do I set the 34–40 A adjustable range on the 3RU2126-4FB00-8K for my motor?

A: Turn the setting dial to the motor’s nameplate full-load current (FLC) — the FLC must fall within the 34–40 A range of this device. Setting it at the motor FLC (not the maximum of the range) gives correct overload trip timing while still riding through normal starting inrush. If the motor FLC is outside this range, select the adjacent rating in the same series.

Q: Does the 3RU2126-4FB00-8K 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 3RU2126-4FB00-8K 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) — ensure the FLC is within the 34–40 A range of this relay. 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 3RU2126-4FB00-8K?

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 3RU2126-4FB00-8K when the application specifically requires overload relay characteristics.

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