Siemens 6SE6440-2UD21-5AA1 — MICROMASTER 440 Drive, 1.5 kW, 380–480 V, Without Filter

Part No.: 6SE6440-2UD21-5AA1 | Range: MICROMASTER 440 | Power: 1.5 kW | Input: 3-Phase 380–480 V AC | Enclosure: IP20 | Filter: Not included

Product Overview

Running a motor at full line frequency when the process only demands partial speed wastes energy, generates unnecessary mechanical wear, and leaves operators with no way to fine-tune process speed or torque. The Siemens 6SE6440-2UD21-5AA1 MICROMASTER 440 inverter is engineered to solve exactly that.

The MICROMASTER 440 is Siemens' proven general-purpose variable-frequency drive platform, spanning 0.12 kW to 250 kW across its full range. The 6SE6440-2UD21-5AA1 sits at the compact end — 1.5 kW, three-phase 380–480 V input, Frame A dimensions — making it the standard selection for smaller motors on conveyors, fans, pumps, compressors, and a wide range of general production machinery.

What distinguishes the MM440 from a basic V/f inverter is the depth of its control architecture. Sensorless vector control, closed-loop vector operation, and Flux Current Control (FCC) are all packed into the same compact housing. Torque can be managed accurately at low speeds without a shaft encoder on every drive. For applications that simply need a reliable V/Hz curve, that mode is factory pre-programmed and operational on first power-up.

This listing is for the without-filter variant. The '2UD' designation in the part number confirms no internal EMC filter is fitted — the standard choice for installations with an external line filter already in place, for IT power system environments, or where the cabinet layout calls for side-by-side drive mounting without thermal derating.

Technical Specifications

Understanding "Without Filter" — What It Means for Your Installation

The absence of an internal EMC line filter is not a limitation — it is a deliberate engineering choice that gives the installer meaningful flexibility across three common scenarios.

External filtration is already in place. Many panel builders fit a single, correctly rated external EMC filter at the cabinet feed point that covers multiple drives sharing the same supply bus. In that configuration, fitting individual internal filters to each drive is redundant in both cost and panel space.

IT (isolated neutral) power systems. Facilities with IT earthing — hospitals, offshore platforms, and certain European industrial buildings — require filter-free drives. The Y-capacitors inside a standard filtered drive create ground leakage paths that are incompatible with the floating earth topology of an IT system.

Side-by-side mounting in compact panels. The without-filter version carries a smaller thermal footprint and supports adjacent mounting without forced air derating. Where space is constrained and drives are racked together, the filter-free variant is the practical solution.

If EN 55011 Class A or Class B compliance is required and no external filter is in place, Siemens produces compatible external line filters sized for the Frame A current rating, as well as filtered-version equivalents within the 6SE6440 product range.

Key Features

Sensorless Vector Control The MM440 delivers significantly tighter low-speed torque performance than a standard V/Hz curve — without an encoder on the motor shaft. For the majority of industrial applications, this eliminates the cost and maintenance burden of encoder feedback while still achieving stable speed regulation and consistent torque output down to near-zero speeds.

BICO Technology — Connecting Signals in Software Siemens' Binary Interconnect (BICO) system allows any drive input signal to be assigned to any control function through parameter settings rather than cabinet rewiring. Setpoint sources, command sources, relay output triggers, and analog output signals can all be freely reassigned. This reduces the need for external relays and logic hardware and simplifies fault-finding when control behaviour needs to change.

Integral Brake Chopper Across the Full Power Range A dynamic braking chopper is built into the 6SE6440-2UD21-5AA1 and is ready for connection to an external braking resistor. This means controlled deceleration and braking capability comes standard — no separate brake chopper module needed in the panel. The chopper is fully rated, not a reduced-duty option fitted only to larger frame sizes.

Six Isolated Digital Inputs With NPN/PNP Selection All six digital inputs are galvanically isolated and switchable between NPN sink and PNP source logic via on-board DIP switches — no rewiring required when integrating with PLCs from different manufacturers or different logic conventions. Each input is independently programmable to any function in the MM440's parameter list.

Adjustable Switching Frequency Up to 16 kHz Higher switching frequencies push motor audible noise well above the range that causes operator discomfort or interference with sensitive process equipment. The switching frequency is adjustable through parameters, with the drive's thermal model automatically managing any derating required at higher settings.

Flying Restart and Auto-Restart Flying restart allows the drive to synchronise with and re-control a motor that is still spinning after a power interruption — avoiding the mechanical stress of trying to start into a rotating load. Auto-restart attempts to resume operation automatically after a fault clears, with configurable retry counts and intervals, reducing manual intervention requirements on remote equipment.

Typical Application Areas

The 1.5 kW power rating and Frame A footprint suit a broad range of smaller AC motor applications across multiple industry sectors:

• Conveyor systems — belt, roller, and chain conveyors requiring variable feed rate, controlled acceleration, or soft-start duty
• Centrifugal pumps — water supply, circulation, and chemical dosing pumps where speed-based flow control replaces throttle valves
• Fans and blowers — HVAC supply/extract fans, cooling tower fans, and process ventilation where affinity law savings at partial load are commercially significant
• Mixers and agitators — food, chemical, and pharmaceutical applications with adjustable process speed and torque requirements
• Packaging machinery — form-fill-seal, wrapping, and labelling equipment requiring speed synchronisation between stations
• Machine tool auxiliaries — coolant pumps, hydraulic power unit motors, and tool magazine drives on CNC equipment
• Small hoisting and lifting — the integral brake chopper and compound braking capability make the MM440 appropriate for vertical conveyor and small hoist applications
• HVAC and building services — air handling units, pressurisation sets, and chiller pumps in commercial and industrial buildings

Control Terminal Summary

Part Number Format Decoded

Understanding the Siemens part number structure helps confirm the correct variant before ordering:

Common search variants: 6SE64402UD215AA1 · 6SE6440 2UD21 5AA1 · MM440 1.5kW 400V · MICROMASTER440 6SE6440-2UD21-5AA1

Frequently Asked Questions

Q: What is the MICROMASTER 440 and how does it differ from the MICROMASTER 420?

A: Both are Siemens general-purpose inverter drives, but the MM440 is the more capable platform. The core differences come down to control modes and braking. The MM440 supports sensorless vector control, closed-loop vector control with an encoder, Flux Current Control, and an integral brake chopper fully rated across its entire power range — none of which are available on the MM420. The MM420 is a V/f-only drive suited for straightforward pump and fan duty. If your application needs accurate low-speed torque, controlled deceleration, or any form of vector operation, the MM440 is the correct product.

Q: Does the 6SE6440-2UD21-5AA1 require an external EMC filter for CE-marked machinery in Europe?

A: It depends on the installation environment. The without-filter version does not independently achieve EN 55011 Class B compliance for first-environment (residential and light commercial) installations. In a second-environment industrial installation, or where a compatible external line filter is fitted ahead of the drive, the system-level requirement can be met. If you are building CE-marked machinery for first-environment use without any external filter, you should use the filtered equivalent or add a matched Siemens external line filter. We can advise on the correct accessory for this frame size.

Q: Can I add an operator panel to this drive after it is installed?

A: Yes. The drive ships without a BOP or AOP, but both connect via the front panel port and can be added at any time. The Basic Operator Panel (BOP) is sufficient for commissioning, fault reading, and manual speed control. The Advanced Operator Panel (AOP) adds a multi-line text display and the ability to clone parameter sets between drives — particularly useful when replacing a unit in an established installation.

Q: How do I connect this drive to a Siemens S7 PLC over PROFIBUS?

A: The built-in RS485 port supports USS protocol communication with Siemens controllers. For full PROFIBUS DP integration, a separate PROFIBUS communication module slots into the drive's option port. Once fitted, the drive appears as a standard DP slave and can be controlled via Siemens drive function blocks in STEP 7 or TIA Portal. DeviceNet and CANopen modules are available for integration into other automation platforms.

In Stock — Ready for Immediate Dispatch
The Siemens 6SE6440-2UD21-5AA1 listed here is genuine stock, available for dispatch within 1–2 business days of confirmed payment. Units ship in original Siemens packaging via DHL Express, FedEx International Priority, UPS, or TNT — buyer's choice. Tracking is provided as soon as the carrier collects.
Import duties and taxes are payable by the buyer at the destination port. A commercial invoice and packing list are provided with every shipment; certificate of origin is available on request.
Have a compatibility question before ordering? Send us your motor nameplate data, panel layout, or control system details — we are happy to confirm suitability and advise on any accessories required to complete the installation.