Inverter 6SE6420-2UD17-5AA1 6SE6 420-2UD17-5AA1 6SE642O-2UD17-5AA1

Siemens 6SE6420-2UD17-5AA1 | MICROMASTER 420 Inverter Drive — 0.75 kW CT / 3AC 380–480V / 3.70A / No Filter

MICROMASTER 420 — Simple, Compact Variable Speed Drive for Standard Applications

The 6SE6420-2UD17-5AA1 is the 0.75 kW member of Siemens' MICROMASTER 420 drive range — a variable speed drive for standard AC motor speed control in general industrial applications. At 0.75 kW on a 380–480V three-phase supply, this is the entry-level power class of the MM420 range: pumps, fans, conveyor sections, small compressors, and general machine drive applications where speed control is required but advanced drive functions are not.

The "without filter" designation is the defining purchasing decision point for this variant. The MICROMASTER 420 is available in two configurations — with or without a built-in EMC filter. The built-in filter reduces conducted high-frequency noise on the mains supply, allowing the drive to meet the EMC emission limits for its environment without additional external components. The filter-less variant (this unit) is smaller and lower cost but requires an external EMC filter to meet conducted emission standards if the installation site requires it.

External filter selection is determined by the drive's rated current (3.70A), cable lengths, and the site's emission class requirement (Category C2 or C3 under EN 61800-3). For installations in residential or light industrial environments where strict emission limits apply, the external filter is mandatory. For installations in heavy industrial environments on private networks, the drive may operate without an external filter subject to the site's EMC assessment.

At 96% efficiency and a power factor of 0.95, the MM420 draws close to its rated real power from the mains without significant reactive component, reducing the apparent power demand on the supply infrastructure.

Key Specifications

HO (Heavy-Overload) Current Rating

The input current specification of 3.70A is the Heavy Overload (HO) rated current. The MICROMASTER 420's HO rating covers constant torque loads where the drive may see peak overload currents significantly above the continuous rated current — conveyor drives, compressors, and mixing applications where starting or transient loads create current peaks.

The HO rating provides the overload margin for these applications. For fan and pump applications with low starting torque, the drive can typically serve a higher rated motor power at the Light Overload (LO) rating.

FAQ

Q1: What is the difference between the filter and no-filter variants of the MICROMASTER 420?

The filter variant includes a built-in EMC input filter, suppressing conducted high-frequency emissions generated by the drive's switching action from propagating onto the mains supply. The no-filter variant (6SE6420-2UD17-5AA1) omits this filter — the drive is more compact and costs less but requires an external EMC filter for EMC compliance in most industrial and all residential/commercial installations. The drive functionality is identical between the two variants.

Q2: What motor size does the MM420 0.75kW drive at 380–480V support?

The 6SE6420-2UD17-5AA1 drives a 0.75 kW (1 HP) standard three-phase induction motor at 380–480V. The drive is matched to the motor power class — the motor nameplate should show 0.75 kW at 380–480V (Y connection). Do not connect a significantly larger motor; the drive's rated current of 3.70A sets the maximum continuous motor current it can supply.

Q3: Does the MICROMASTER 420 support the STO (Safe Torque Off) safety function?

The basic MICROMASTER 420 (6SE6420 series) does not support STO as a certified safety function — this is a key distinction from the later SINAMICS G120 series. For applications requiring certified STO or other functional safety functions (SIL 2 / PLd), the SINAMICS G120 with a PM (Power Module) and CU (Control Unit) with safety functions is the appropriate selection.

Q4: What communication protocols does the MICROMASTER 420 support?

The MM420 base unit provides a serial RS-485 port supporting the USS (Universal Serial Interface) protocol for remote parameter access, speed setpoint, and start/stop commands. An optional PROFIBUS communication board can be added for PROFIBUS DP integration. The drive does not natively support PROFINET or Ethernet-based protocols without additional hardware.

Q5: Can the 6SE6420-2UD17-5AA1 be repaired, and where is it sourced?

Yes. MICROMASTER 420 drives are repairable through Siemens drive service and specialist drive repair centres. Common failure points include the IGBT transistors, electrolytic DC bus capacitors, gate driver boards, and control card faults. The MM420 is a mature product with a large installed base; both new and tested refurbished units are available through Siemens' own supply and through the established MM420 aftermarket. Confirm the full part number including 2UD17-5AA1 to ensure the correct power/voltage/filter configuration.