6SE7021-8TB31 SIMOVERT MASTERDRIVES

SKU: 6SE7021-8TB31 Category: Drive

Description
Additional information

The Siemens SIMOVERT MASTERDRIVES 6SE7021-8TB31 is a vector control AC drive belonging to the SIMOVERT MASTERDRIVES MC (Motion Control) and VC (Vector Control) series. This unit is designed for variable-speed control of three-phase asynchronous and synchronous motors, providing precise speed and torque regulation in demanding industrial environments. The 6SE7021-8TB31 is a compact, cabinet-mounted inverter unit rated for medium power applications within the MASTERDRIVES product family.

The 6SE7021-8TB31 operates from a three-phase 380–480 V AC supply and delivers a continuous output current of 18 A, corresponding to a power rating of approximately 7.5 kW. It supports a range of communication options including PROFIBUS-DP via optional CBP2 boards, as well as the SIMOLINK and USS protocol interfaces. The drive features closed-loop vector control with or without encoder feedback, integrated pulse-width modulation, and supports a switching frequency of up to 16 kHz. It is housed in a compact chassis format with a protection rating of IP20, suitable for installation within control cabinets.

The SIMOVERT MASTERDRIVES series is widely deployed in machine tools, textile machinery, printing presses, paper and film processing lines, and material handling systems. The 6SE7021-8TB31 is particularly suited to applications requiring dynamic speed control, coordinated multi-axis motion, and regenerative braking capability. Its compatibility with Siemens SIMATIC automation systems and support for encoder feedback makes it a reliable choice for precision drive applications in manufacturing and process industries.

Technical Specifications

Input Voltage	380–480 V AC (3-phase)
Output Current (Continuous)	18 A
Power Rating	7.5 kW
Control Type	Vector Control (VC) / Sensorless Vector Control
Switching Frequency	Up to 16 kHz
Communication Interface	USS protocol (standard); PROFIBUS-DP via optional CBP2 module
Protection Rating	IP20
Mounting	Cabinet / Chassis mounting
Operating Temperature	0 °C to +40 °C
Storage Temperature	-25 °C to +70 °C
Relative Humidity	15–95% (non-condensing)
Motor Compatibility	Three-phase asynchronous and synchronous motors
Encoder Support	Incremental encoder via optional SBP/SBM board
Braking Resistor Support	Yes, external braking resistor compatible
Series/Product Family	SIMOVERT MASTERDRIVES

Common Fault Codes

F001: Overcurrent: Output current has exceeded the permissible limit, typically caused by a short circuit, motor fault, or excessive load.
Check motor wiring for short circuits, verify motor parameters are correctly programmed, and reduce acceleration ramp if necessary.
F002: Overvoltage: DC link voltage has exceeded the maximum threshold, often caused by regenerative energy during deceleration.
Extend the deceleration ramp time, verify supply voltage is within specification, or connect an external braking resistor.
F003: Undervoltage: DC link voltage has dropped below the minimum threshold, indicating a supply voltage dip or failure.
Check the input supply voltage and connections. Verify that the supply is stable and within the rated input voltage range.
F004: Overtemperature (Heatsink): The drive heatsink temperature has exceeded the permissible limit.
Check that ambient temperature is within specification, ensure adequate ventilation and cooling airflow, and clean any blocked air vents.
F005: Overtemperature (Motor): Motor temperature has exceeded the set threshold as detected by PTC thermistor or I2t monitoring.
Check motor load and duty cycle, verify PTC thermistor wiring, and allow the motor to cool before restarting.
F011: Ground Fault: A ground fault has been detected on the output side of the drive.
Disconnect the motor and check motor winding insulation resistance. Inspect output cabling for damage or insulation breakdown.
F023: Output Phase Failure: One or more output phases are missing or have an open circuit.
Check motor cable connections at the drive output terminals and at the motor terminal box. Verify all three phases are connected.
F035: EEPROM Fault: A read or write error has occurred in the drive's non-volatile parameter memory.
Perform a factory reset and re-enter drive parameters. If the fault persists, the control board may require replacement.

Frequently Asked Questions

What is the output power rating of the 6SE7021-8TB31?

The 6SE7021-8TB31 is rated for approximately 7.5 kW with a continuous output current of 18 A, suitable for medium-duty motor control applications.

What input voltage does the 6SE7021-8TB31 require?

This drive requires a three-phase AC supply in the range of 380 to 480 V AC at 50/60 Hz.

Does the 6SE7021-8TB31 support PROFIBUS-DP communication?

PROFIBUS-DP is not built in as standard but can be added via the optional CBP2 communication board, which plugs into the drive's option slot.

Can the 6SE7021-8TB31 operate without an encoder (sensorless)?

Yes, the drive supports sensorless vector control for applications that do not require encoder feedback, as well as closed-loop vector control when an encoder module such as the SBP is installed.

What protection rating does the 6SE7021-8TB31 have?

The unit carries an IP20 protection rating and is intended for installation inside a suitable control cabinet to provide additional environmental protection.

Troubleshooting

Drive displays F002 overvoltage fault during deceleration

Measure the DC link voltage during deceleration. If it exceeds the overvoltage threshold, regenerative energy from the motor is not being dissipated adequately.

Extend the deceleration ramp time in the drive parameters, or connect a suitably rated external braking resistor and enable the braking chopper function.

Drive fails to start and displays F001 overcurrent immediately on run command

Check output terminals for short circuits between phases or to earth. Verify that motor nameplate data entered in the drive parameters matches the actual motor.

Correct any wiring faults, re-enter accurate motor data, and perform a motor identification run if supported. Reduce the acceleration ramp rate if the motor load is high.

Drive powers up but display is blank or unresponsive

Check the 24 V DC control supply voltage at the relevant terminals. Inspect the internal control board for visible damage or blown fuses.

Restore the 24 V DC supply if absent. Replace any blown control fuses. If the control board is faulty, it will require repair or replacement.

PROFIBUS communication loss between drive and PLC

Verify the CBP2 option board is correctly seated in the drive option slot. Check PROFIBUS cable termination resistors and node address settings.

Re-seat the CBP2 board, verify the correct PROFIBUS node address is set in the drive parameters, and ensure bus termination is applied only at the two physical ends of the network.

Drive overheats and trips on F004 heatsink overtemperature

Check ambient temperature inside the control cabinet and measure airflow across the drive heatsink. Inspect cooling fans for operation and check for blocked ventilation slots.

Reduce ambient temperature by improving cabinet ventilation or adding forced cooling. Clean blocked air vents and replace any failed cooling fans. Derate the drive if ambient temperature consistently exceeds 40 °C.

Condition	Repair, Used, Refurbished, New in box (sealed)