Emerson Control Techniques Unidrive Modules: UNI3405

Technical Dossier

Product Details And Specifications

Control Techniques Unidrive Series: Comprehensive Module Range and Technical Overview

The Control Techniques Unidrive series, developed by Emerson Industrial Automation (now Nidec Control Techniques), is one of the most widely deployed AC variable speed drive platforms in global heavy industry. Installed across petrochemical refineries, nuclear power auxiliary systems, offshore platforms, pulp and paper mills, and large-scale water treatment facilities, the Unidrive platform is recognized for its closed-loop vector control capability, multi-mode operation (open-loop, closed-loop RFC, servo), and robust industrial communication support. The UNI3405 and its siblings remain active in legacy DCS and PLC-integrated architectures worldwide, with a substantial installed base that continues to require spare parts, repair, and lifecycle extension support.

The Evolution of Unidrive Architecture

The Unidrive platform was introduced in the mid-1990s as a modular, high-performance drive designed to replace earlier generation DC and basic AC drives in demanding process applications. The original Unidrive Classic (UNI-series) established the platform's reputation for closed-loop vector and servo control in a single hardware frame. Key architectural milestones include:

Unidrive Classic (1995–2005): Frame sizes 1–6, covering 0.75 kW to 1.4 MW. Supported open-loop V/Hz, closed-loop flux vector, and servo modes via a unified parameter set. The UNI3405 belongs to this generation — Frame 3, 4.5 kW (400V) or 5.5 kW (200V) output rating.

Unidrive SP (2003–2015): Introduced the Solutions Module slot architecture, enabling plug-in fieldbus adapters (PROFIBUS, DeviceNet, CANopen, Ethernet) and encoder interface modules. Backward-compatible parameter structure eased migration from Classic units.

Unidrive M (2012–present): Current-generation platform. Modular design with dedicated M200, M300, M400, M600, M700, M800 sub-series targeting specific application tiers. Supports EtherCAT, PROFINET, and Ethernet/IP natively. The M-series is the designated migration path for all Classic and SP installations.

Compatibility note: Unidrive Classic units use a proprietary CT-Net serial network and RS485 Modbus interface. Direct fieldbus integration requires an external gateway or upgrade to SP/M-series hardware. Parameter migration between Classic and SP requires manual remapping — no automatic conversion tool is available from the OEM.

Unidrive Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly stocked models within the Unidrive Classic and SP series. Each entry reflects the drive's frame size, power rating, and primary application role.

UNI1401: Frame 1, 0.75 kW / 400V, open-loop and closed-loop vector, DIN-rail compatible compact drive.
UNI1402: Frame 1, 1.1 kW / 400V, general-purpose conveyor and pump duty, RS485 Modbus standard.
UNI2401: Frame 2, 1.5 kW / 400V, closed-loop vector with encoder feedback, servo-capable variant.
UNI2402: Frame 2, 2.2 kW / 400V, multi-mode operation, suitable for tension control applications.
UNI2403: Frame 2, 3.0 kW / 400V, enhanced current limit for high-inertia load starting.
UNI3401: Frame 3, 2.2 kW / 200V, compact three-phase input, servo and spindle duty.
UNI3402: Frame 3, 3.0 kW / 400V, standard industrial duty, CT-Net and Modbus RTU interface.
UNI3403: Frame 3, 3.7 kW / 400V, closed-loop RFC mode, quadrature encoder input standard.
UNI3404: Frame 3, 4.0 kW / 400V, high-dynamic servo mode, ±10V analog reference input.
UNI3405: Frame 3, 4.5 kW / 400V (5.5 kW / 200V), closed-loop vector and servo, CT-Net, RS485 Modbus, 0–10V / 4–20mA analog I/O, digital I/O x6, relay output x2. Core replacement unit for legacy DCS-integrated servo axes.
UNI3406: Frame 3, 5.5 kW / 400V, extended overload rating 150% for 60 s, crane and hoist duty.
UNI4401: Frame 4, 7.5 kW / 400V, four-quadrant regenerative braking capable, winder/unwinder duty.
UNI4402: Frame 4, 11 kW / 400V, closed-loop vector, integrated EMC filter Class C2.
UNI4403: Frame 4, 15 kW / 400V, high-performance spindle drive, encoder resolution to 65536 ppr.
UNI5401: Frame 5, 18.5 kW / 400V, multi-drive common DC bus capable, regenerative front-end compatible.
UNI5402: Frame 5, 22 kW / 400V, process industry duty, ATEX-compatible motor interface.
UNI5403: Frame 5, 30 kW / 400V, large pump and fan duty, PID process controller built-in.
UNI6401: Frame 6, 37 kW / 400V, cabinet-mount, parallel drive operation for high-power axes.
UNI6402: Frame 6, 45 kW / 400V, regenerative braking standard, suitable for test bench and dynamometer duty.

Sourcing Hard-to-Find & Obsolete Unidrive Parts

The Unidrive Classic series reached end-of-active-production in approximately 2008, with OEM repair support formally discontinued by Nidec Control Techniques for most frame sizes. However, the installed base across refineries, power generation facilities, and continuous process plants remains substantial, and replacement with current-generation M-series drives requires engineering re-commissioning that many facilities defer due to cost and downtime constraints.

DriveKNMS maintains a dedicated inventory of Unidrive Classic units including UNI3405 and adjacent frame sizes, sourced through controlled decommissioning projects, OEM surplus channels, and verified third-party refurbishers. All units are subject to incoming inspection before entering stock. For obsolete variants with no available new-old-stock equivalent, DriveKNMS offers board-level repair and functional restoration services with a defined warranty period. Customers operating under long-term maintenance contracts for legacy DCS systems — including Honeywell TDC 3000, Yokogawa CENTUM, and ABB Advant integrations — are supported with documented traceability records on request.

Quality Control for the Unidrive Range

Unidrive Classic units present specific test challenges due to their multi-mode firmware architecture and the interaction between the drive's internal parameter set and connected encoder or resolver feedback devices. DriveKNMS applies the following test protocol to all Unidrive units processed through its facility:

Power stage verification: DC bus capacitor ESR measurement, IGBT gate drive signal integrity check, and full-load thermal cycling at rated current for a minimum of 30 minutes.
Control board diagnostics: Firmware version identification, parameter default restore, and functional test of all analog and digital I/O channels against published specifications.
Communication interface test: RS485 Modbus RTU loopback test at 9600 and 19200 baud; CT-Net node address assignment and polling verification where applicable.
Encoder feedback simulation: Closed-loop RFC mode test using a calibrated quadrature encoder simulator to verify speed regulation accuracy within ±0.1% of set point.
Final run test: Motor coupled load test at 25%, 50%, and 100% rated torque with data-logged output frequency, current, and DC bus voltage recorded for traceability.