Siemens 3VL7712-1TF46-8TE1 VL1250N MCCB Unit

Module Feature

3VL7712-1TF46-8TE1 belongs to Siemens Sentron 3VL VL1250N series molded case circuit breaker. It is equipped with ETU20 LSI electronic trip unit, supports long-time overload, short-time delay and instantaneous short-circuit protection. Rated frame current 1250A, adjustable Ir range 500~1250A, 4-pole design with neutral pole protection. Icu 55kA at 415V, suitable for heavy industrial distribution. This variant comes with factory fitted auxiliary switch and shunt trip coil for remote tripping and status feedback. Widely stocked as spare for factory main switchboard, power plant auxiliary LV switchgear and large building distribution cabinets.

Working principle

CT sensors collect three-phase current signals and send data to ETU20 trip electronic unit. The internal microprocessor compares measured current with protection setting curves. Overload triggers inverse time delayed trip; short-time fault triggers adjustable short delay trip; severe short circuit triggers instantaneous trip. Shunt trip coil can open contacts by remote control signal. Auxiliary contacts output breaker ON/OFF and trip status to SCADA system.

Onboard components

Current transformer group, ETU20 electronic trip unit, main contact assembly, arc quenching chamber, energy storage operating mechanism, shunt trip coil, auxiliary contact set, operation handle and insulated housing.

LED indicators

Front LEDs indicate power ready, ON, OFF and fault trip status.

Hardware self‑diagnosis

Trip unit continuously monitors CT signal integrity and internal power supply. LSI protection parameters can be modified on local trip panel.

Programming software

Siemens PowerConfig, used for protection curve setup and parameter backup.

Electrical & Process Parameters

Model: 3VL7712-1TF46-8TE1 Brand: Siemens Device type: Molded case circuit breaker Frame rating: 1250 A Pole: 4P Icu: 55 kA @415VAC Trip unit: ETU20 LSI Function: Overload, short-circuit protection, remote trip and status supervision for LV distribution circuits

Mechanical & Structure

Mounting: Panel mounting inside low voltage switchgear Protection class: IP40 front panel Housing: Reinforced insulated plastic housing

Environmental

Operating temperature: -25℃ ~ +60℃ Storage temperature: -40℃ ~ +70℃ Ambient humidity: 5~95% non‑condensing

Certification: CE Status: Original Siemens distribution spare

Installation

Cut off upstream power supply before replacement. Secure breaker to busbar support, tighten bus connection bolts, wire shunt trip and auxiliary contact wiring, set LSI protection parameters, test close, trip and remote shunt function after commissioning.

Interface

Three-phase + neutral main power terminals, shunt trip terminals, auxiliary alarm/status contact terminals.

Diagnostic

Overload trip: Continuous load current exceeds long delay setting. Instant short trip: Short-circuit fault on downstream cable or load. Remote trip failure: Shunt coil supply missing or wiring open.

Product Brief

3VL7712-1TF46-8TE1 breaker, Siemens VL1250N 4P 1250A frame MCCB spare for industrial main incoming and bus tie low voltage protection replacement.