Siemens 3RT2936-1BB00 Varistor Surge Suppressor, S2/S3 Original Brand New

Overview

The Siemens 3RT2936-1BB00 is an essential varistor surge suppressor designed for the reliable protection of the control coil circuits in Siemens SIRIUS 3RT2 power contactors. Specifically engineered for contactor sizes S2 and S3 (corresponding to the 3RT2.3 and 3RT2.4 series), this clip-on module prevents damaging voltage peaks caused by switching off inductive loads.

This versatile surge protection device handles a wide range of control voltages, operating with 24 V to 48 V AC (at 50/60 Hz) and 24 V to 70 V DC. Its compact, push-fit design allows for simple and fast mounting directly onto the contactor, ensuring maximum protection without affecting the contactor’s external dimensions or requiring complex wiring.

Benefit 

1. Extended Contactor Lifespan: The varistor suppresses high-energy voltage peaks that occur when the contactor coil is de-energized, preventing premature wear and damage to the coil and associated control components.
2. Circuit Reliability: Protects sensitive electronic components in the control system (like PLCs or relays) from transient overvoltages, ensuring stable and reliable operation of your machinery.
3. Space and Time Saving: The compact, clip-on design allows for tool-free, rapid installation, saving assembly time and maintaining a uniform appearance within the control cabinet.
4. Universal AC/DC Application: A single component solution for both AC and DC control circuits within the specified voltage range, simplifying inventory and selection.
5. Part of the SIRIUS Modular System: Fully compatible and integrated into the renowned Siemens SIRIUS modular system for industrial controls.

Function

A varistor (Voltage-Dependent Resistor) protects the control circuit by shunting the transient energy away from the contactor coil and back into the control circuit when a dangerous overvoltage spike occurs. When the coil is switched off, the energy stored in the coil is released as a high-voltage surge. The varistor’s resistance dramatically drops at this high voltage, clamping the peak voltage to a safe level (typically 2 to 4 times the rated coil voltage) and dissipating the surge energy as heat. This process protects the coil’s insulation and prevents damage to other connected devices.

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