Siemens MICROMASTER 440 VFD 5.5kW 200-240V 3-Phase 6SE6440-2UC25-5CA1

Siemens MICROMASTER 440 VFD 5.5kW – Maximum C-Size Vector Drive for 200V Systems

The Siemens MICROMASTER 440, model 6SE6440-2UC25-5CA1, delivers 5.5kW constant torque output power with 200-240V 3-phase input, with square-law torque rating extending to 7.5kW for pump and fan applications[reference:38]. This C-size unfiltered drive represents the maximum power rating in the compact C-size chassis before transitioning to the larger D-size platform.

This model serves as the transition point within the MM440 200V product line. For applications requiring up to 5.5kW constant torque, it offers the highest power density available in the C-size enclosure. The drive's robust overload capability (150% for 60 seconds, 200% for 3 seconds) provides ample margin for high-inertia starts, making it particularly suitable for large fans with significant moment of inertia and conveyors starting under load[reference:39].

The sensorless vector control algorithm maintains 100% rated torque down to 0.5 Hz without requiring encoder feedback, a critical feature for applications like extruders and mixers where low-speed torque is essential. The built-in braking chopper allows dynamic braking when used with an external resistor, supporting controlled deceleration for high-inertia loads.

Key Specifications:
- Output Power: 5.5 kW (constant torque) / 7.5 HP
- Square-Law Torque Power: 7.5 kW (pumps, fans, centrifugal loads)[reference:40]
- Input Voltage: 200-240V AC 3-phase only, +10/-10%, 47-63Hz[reference:41]
- Input Current: 34.2 A (constant torque)[reference:42]
- Rated Output Current: 22 A (constant torque)[reference:43]
- Output Frequency: 0-650 Hz
- Overload Capacity: 150% for 60 s, 200% for 3 s[reference:44]
- Protection Class: IP20
- Operating Temperature: -10°C to +50°C
- Dimensions (H×W×D): 245mm × 185mm × 195mm[reference:45]
- Weight: 5.5 kg[reference:46]
- Filter: Without built-in filter
- Frame Size: C

Typical Applications:
- Large industrial conveyors (belt and roller types)
- High-inertia centrifugal fans and blowers
- Centrifugal pumps with variable speed requirements
- Small to medium extruders for plastics and rubber
- Industrial mixers for heavy materials (concrete, mortar, bulk solids)
- Small compressors (screw type, piston type)
- Woodworking machinery (planers, saws, jointers)

Key Features:
- Sensorless vector control delivers full torque from zero speed without encoder
- Built-in braking chopper (external resistor required for dynamic braking)
- BiCo technology for custom I/O configuration
- Integrated Modbus RTU (RS-232 and RS-485)
- PID controller for closed-loop process control (pressure, flow, temperature)
- 6 digital inputs, 2 analog inputs, 2 analog outputs, 3 relay outputs
- Flying restart captures coasting motors
- DC injection braking for holding torque
- 4 skip frequencies for resonance avoidance
- Automatic restart after fault clearing

Application Case: Large Exhaust Fan Control
In a 24/7 industrial ventilation application, this 5.5kW drive would typically achieve energy savings of 30-50% when controlling a variable-speed fan compared to fixed-speed operation or inlet damper control. The drive's built-in PID can maintain constant duct pressure with minimal programming, while the flying restart function ensures smooth re-engagement if power is momentarily interrupted.

Important Notes:
- This product is discontinued (PM410). Available ONLY as a spare part[reference:47]
- Requires 3-phase input only; single-phase operation not supported at this power level
- For EMC compliance in certain environments, external filter may be required
- A BOP or AOP is required for parameter configuration beyond factory defaults
- SINAMICS G120 series recommended for new installations

FAQ:

Q1: What is the difference between constant torque (5.5kW) and square-law torque (7.5kW) ratings?
A: Constant torque rating applies to loads requiring consistent torque across speed range (conveyors, positive displacement pumps, extruders). Square-law rating applies to centrifugal pumps and fans where torque increases with the square of speed, allowing the same drive to handle a larger motor (7.5kW) due to the lower torque requirements at reduced speeds.

Q2: Why would I choose this over the larger D-size models?
A: If 5.5kW meets your power requirements, this C-size model offers the smallest physical footprint (245×185×195mm) and lower cost. The D-size chassis (520mm height) is significantly larger and only required for higher power applications.

Q3: Does this drive include a braking resistor?
A: No. The drive includes a built-in braking chopper (braking transistor), but the external braking resistor must be ordered separately. For pump and fan applications without dynamic braking requirements, a resistor may not be necessary.

Q4: What is the recommended cooling clearance?
A: Allow 100mm clearance above and below the drive for proper natural convection airflow. For side-by-side mounting, no horizontal clearance is required, but ensure adequate overall cabinet ventilation.

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