Product Overview
The Emerson SP4403 is a Frame 4 member of the Unidrive SP universal AC drive family, originally developed by Control Techniques and marketed under the Emerson Industrial Automation brand before the business transitioned to Nidec Control Techniques . What distinguishes the Emerson SP4403 from conventional variable frequency drives is its unified hardware architecture: a single power stage and control platform supports induction motors, permanent-magnet synchronous motors, and servo motors through selectable firmware modes rather than requiring separate drive families . This design philosophy allows facilities to standardize spare-parts inventory across diverse motor-driven processes, from simple fans and pumps to precision web-handling systems requiring closed-loop position control.
The Emerson SP4403 occupies the upper-mid power band of the Unidrive SP range, with a three-phase 380–480 V AC input and a continuous output current rated at 96 A for heavy-duty applications or 104 A for normal-duty loads. The drive is now an end-of-life product, with original equipment manufacturing discontinued; the market supply consists of surplus, refurbished, and tested used units . For maintenance organizations supporting legacy Unidrive SP installations, the Emerson SP4403 remains valuable precisely because its mechanical footprint, terminal pattern, and parameter architecture are fixed—a failed unit can be replaced with a tested spare without re-engineering the panel or rewriting the control program .
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | Emerson SP4403 |
| Manufacturer | Emerson / Control Techniques (now Nidec) |
| Product Type | Universal AC Variable Speed Drive (VFD) |
| Series | Unidrive SP, Frame 4 |
| Input Voltage | 3-phase 380–480 V AC ±10% |
| Input Frequency | 48–65 Hz |
| Continuous Output Current | 96 A (heavy duty) / 104 A (normal duty) |
| Motor Rating | 45 kW / 60 HP (heavy duty); 55 kW / 75 HP (normal duty) |
| Overload Capacity | 150% for 60 seconds |
| Output Frequency | 0–550 Hz (0–600 Hz reported by some sources) |
| Control Modes | Open-loop V/f, open-loop vector, RFC, closed-loop vector, servo |
| Motor Types Supported | Induction, permanent-magnet synchronous, servo |
| Option Slots | 2 (communication / I/O / encoder expansion) |
| Braking | Built-in dynamic brake transistor, DC injection braking |
| Protection Rating | IP20 |
| Operating Temperature | 0°C to +40°C (derating required above 40°C or 3 kHz switching) |
| Dimensions (approx.) | 310 × 510 × 298 mm |
| Weight (approx.) | 30 kg |