SIEMENS 3WT9841-0JB000 Product Description

Overview

SIEMENS 3WT9841-0JB000 is an ETU2WT electronic overcurrent release designed for the Siemens 3WT8 air circuit breaker series. SIEMENS 3WT9841-0JB000 provides LSI protection functions for low-voltage power distribution circuits, including long-time overload protection, short-time delay short-circuit protection and instantaneous short-circuit protection. SIEMENS 3WT9841-0JB000 serves as the core protection control unit of the 3WT8 breaker and supports on-site status indication and function test.

Features

SIEMENS 3WT9841-0JB000 adopts LSI three-section protection logic, and each protection threshold can be adjusted to match different load characteristics. It is equipped with an LED trip indicator to visually display the trip cause after fault action for fast troubleshooting. The built-in test button allows maintenance personnel to verify the protection function without applying high primary current. SIEMENS 3WT9841-0JB000 is directly installed inside the 3WT8 air circuit breaker and works with the current transformer of the breaker to sample line current continuously. It follows IEC 60947-2 standard and has stable anti-interference performance in power distribution cabinets. It can replace the original release unit of 3WT8 breakers for maintenance and retrofit, and it supports basic power protection without complex communication expansion. SIEMENS 3WT9841-0JB000 helps avoid equipment damage caused by overload and short-circuit faults in the power supply loop.

Specs

Brand: SIEMENS Model: 3WT9841-0JB000 Product type: Electronic overcurrent release Release type: ETU2WT Protection characteristic: LSI, long time, short time, instantaneous Compatible breaker: 3WT8 air circuit breaker Indication: LED trip indicator Auxiliary function: Integrated test function Applicable standard: IEC 60947-2 Installation: Internal assembly for 3WT8 breaker

Principle

SIEMENS 3WT9841-0JB000 receives current sampling signals from the built-in current transformers of the 3WT8 circuit breaker. The internal circuit compares the real-time current value with the preset LSI protection setting parameters. When the current exceeds the corresponding threshold and meets the time-delay condition, SIEMENS 3WT9841-0JB000 outputs a trip signal to drive the breaker operating mechanism to open the main contact and cut off the fault circuit. Meanwhile, the LED indicator lights up to record the trip event. The test function simulates fault signals to check whether the trip loop and logic of the release work normally.

Applications

SIEMENS 3WT9841-0JB000 is widely used in low-voltage power distribution systems with 3WT8 air circuit breakers. It is commonly applied in factory main distribution cabinets, substation power distribution, building power supply, water treatment and industrial equipment power inlet protection. It protects transformers, cables and heavy motor feeders against overload and short-circuit risks, and it is used for power distribution overhaul and spare replacement of 3WT8 breakers.