Siemens 6RA7081-6GV62-0-Z DC Master Drive Unit

Module Feature

6RA7081-6GV62-0-Z belongs to Siemens classic SIMOREG DC Master 70 series DC speed controller.

It adopts thyristor phase-control rectifier structure, supports armature voltage regulation and field excitation control for DC motors. It reserves expansion slots for communication and I/O option boards, compatible with Profibus and encoder feedback modules. This obsolete unit is widely used for old rolling mill, printing, paper machine and extruder DC drive spare replacement.

Working principle

Three-phase AC input is converted to adjustable DC voltage by controlled thyristor bridge.

The control board receives speed setpoint and armature/field feedback signal, executes closed-loop speed and current regulation. It integrates comprehensive protection functions such as overcurrent, over-temperature, field loss and stall, and locks pulse output once fault condition is triggered.

Onboard components

Thyristor power bridge, pulse transformer, armature and field current transformer, main control board, operation panel, cooling fan, power and signal terminal block.

LED indicators

Front panel LEDs indicate power ready, running state, fault alarm and communication status.

Hardware self‑diagnosis

Power-on self-test and continuous monitoring detect phase loss, thyristor fault, over-temperature, field circuit break and encoder signal loss, fault codes can be checked on panel.

Programming software

SIMOREG Parameterization Software, DriveMonitor, used for parameter setting, DC motor tuning and fault record reading.

Electrical & Process Parameters

Model:6RA7081-6GV62-0-Z Brand:Siemens Device type:DC thyristor converter Input voltage:400V 3-phase AC Armature rated current:800A Function:DC motor closed-loop speed and torque control

Mechanical & Structure

Mounting:Cabinet floor mounting

Protection class:IP20

Housing:Metal heavy-duty power chassis

Environmental

Operating temperature:0℃ ~ +40℃

Storage temperature:-40℃ ~ +85℃

Ambient humidity:5~95% non‑condensing

Certification:CE

Status:Siemens original discontinued DC drive spare

Installation

Install in ventilated power cabinet, reserve sufficient heat dissipation space.

Wire three-phase supply, armature cable and field winding cable strictly according to schematic. Complete motor parameter setting and current loop optimization before commissioning. Clean fan and heat sink dust regularly.

Interface

Three-phase AC input terminals, DC armature terminals, field excitation terminals, analog/digital I/O terminals, option expansion slot.

Diagnostic

Overcurrent alarm: Armature short circuit, motor insulation breakdown, wrong current limit parameter.

Field loss fault: Excitation wire open, field power supply failure.

Unstable speed: Speed feedback signal loss or interference, loop parameter mismatched.

No display: Internal auxiliary power supply damage.

Product Brief

Siemens 6RA7081-6GV62-0-Z SIMOREG 70 DC converter, 800A DC drive for paper machine and rolling equipment maintenance replacement.