Simatic Inverter 6SE6440-2UD31-8DB1 6SE6 440-2UD31-8DB1 6SE644O-2UD31-8DB1

6SE6440-2UD31-8DB1 | Siemens MICROMASTER 440 — 18.5kW CT / 22kW LO / 380–480V / 3-Phase / Without Filter / IP20

MICROMASTER 440 at 18.5kW — Mid-High Power Class

The 6SE6440-2UD31-8DB1 positions the MICROMASTER 440 at 18.5kW constant torque — the mid-high power class where the drive transitions from lighter industrial conveyor and packaging applications into heavier machine drives, larger fans and pumps, and significant material handling systems.

At 18.5kW CT and 22kW LO from 380–480V AC, this MM440 covers the power range where many industrial processes deploy their primary production drives:

At 18.5kW constant torque: Crane and hoist auxiliary drives, heavy conveyors with high-inertia loads, compressors requiring full torque at all speeds, and textile and printing machine main drives.

At 22kW square-law torque: Centrifugal fans in industrial HVAC systems, large building management air handling units, and high-head centrifugal pumps where variable speed delivers maximum energy savings.

Key Specifications

18.5kW CT / 22kW LO — Two Overload Profiles for Different Loads

The dual-rating structure of MM440 drives allows one hardware configuration to serve two distinct application types:

18.5kW CT (Constant Torque / High Overload): The drive can deliver 150% of its rated 18.5kW output for 60 seconds and 200% for 3 seconds. This headroom handles motor starts against loaded conveyors, hoist load transients, and brief overloads from process peaks. The CT rating is selected for applications where torque demand can spike significantly above steady-state values.

22kW LO (Low Overload / Square-law): Fan and pump loads follow the cube law — torque scales with the square of speed, power with the cube. These loads rarely demand more than 110% overload in normal operation. By configuring the same drive hardware for LO duty, a larger 22kW motor can be used with the 6SE6440-2UD31-8DB1, accepting reduced overload headroom in exchange for higher continuous output capability.

Application Scenarios

Heavy conveyor drive: A production conveyor's 18.5kW drive motor requires variable speed with high overload capability for loading conditions. 6SE6440-2UD31-8DB1 with FCC vector control provides smooth speed regulation and reliable overload handling.

Large HVAC fan: A 22kW supply air fan in an industrial building requires energy-efficient variable speed. Configured for LO (22kW square-law), 6SE6440-2UD31-8DB1 provides full fan speed range with maximum energy savings at partial load.

FAQ

Q1: What is the difference between CT (18.5kW) and LO (22kW) ratings for 6SE6440-2UD31-8DB1?

CT (18.5kW) provides 150% × 60s overload for applications with transient load spikes. LO (22kW) allows a larger motor but limits overload to 110% × 60s — suitable for fans and pumps where transient overload is minimal. Select CT for conveyors, hoists, compressors; select LO for fans and centrifugal pumps. The drive hardware is identical — the overload capability is defined by the configured operating mode.

Q2: Does 6SE6440-2UD31-8DB1 include a braking chopper?

The MM440 range includes an integrated braking transistor connection point allowing external braking resistor connection. At 18.5kW, the minimum braking resistor value and power rating must be calculated from the drive documentation based on the load's inertia and the required deceleration time. An internal braking chopper transistor manages the resistor switching — only the external resistor itself is a separate component.

Q3: What communication options are available for 6SE6440-2UD31-8DB1?

The built-in RS485 port supports USS protocol for serial communication with a host PLC or HMI. For PROFIBUS DP connectivity, the optional CBP2 communication board plugs into the MM440's option slot — enabling direct SIMATIC S7 PLC integration over PROFIBUS. DeviceNet and other fieldbuses are supported by their respective Siemens option boards.

Q4: What ambient temperature limits apply to 6SE6440-2UD31-8DB1?

The MM440 is rated for ambient temperatures from −10°C to +50°C at full load rating. Above +40°C, some derating of the output current may apply depending on the specific model — confirm from the MM440 datasheet for the exact derating curve. At 18.5–22kW, the drive's internal cooling fan is essential — ensure adequate ventilation clearance around the drive in the control cabinet.

Q5: What operator panel options are available for 6SE6440-2UD31-8DB1?

The MM440 is supplied without an operator panel in this variant. The optional BOP-2 (Basic Operator Panel) provides a local numeric display for parameter access, monitoring, and local run/stop control. The AOP-2 (Advanced Operator Panel) adds a graphical display with plain-text parameter names and a copy function for backing up and restoring drive parameters. Both panels clip onto the drive's panel port without tools.