SP3402 Variable Frequency Drive UNIDRIVE SP 18.5kW 3-ф/380

SP3402 is a frame 3 Unidrive SP rated 18.5 kW HD, 40 A rated current, 3-ph/380. The mid frame 3 model for heavy dynamic loads.

Typical applications:

• Main drives of extruders and calenders
• Wind/unwind stations with tension control
• Powerful conveyors and cranes

Note: a fieldbus for SCADA/PLC (Profibus, CANopen, DeviceNet) is added via an SM module; Modbus RTU/RS-485 is onboard.

Control Techniques Unidrive SP — universal high-performance drive for demanding machines

Unidrive SP is the flagship Control Techniques (now Nidec) family where one platform covers four modes: scalar V/f, sensorless vector for induction motors, closed-loop vector with an encoder, and servo control of PMAC motors. Every model in this lineup is three-phase, 3-ph/380, frame sizes 1–6, IP20, spanning 0.75–110 kW. Let us be honest up front: the series is discontinued. For new equipment, choose the successor Unidrive M701 (a direct SP upgrade) or M700 with onboard Ethernet. The SP itself is mainly relevant today as a replacement for a drive already running on a line.

Important: the model number = Heavy Duty rating

In Unidrive SP designations the power figure is the heavy-duty (HD) rating. For example, SP1401 is 0.75 kW HD at 2.1 A, even though distributors often list 1.1 kW under normal duty (ND). We deliberately state the HD kW and the rated current for each model so you see the real working range, not a marketing figure.

What Unidrive SP is for

• Machinery and machine tools: closed-loop vector with an encoder holds speed and torque where a plain VFD lacks dynamics — spindles, feeds, extruders.
• Servo tasks: the same hardware drives a PMAC servo motor — winders, test rigs, precise positioning.
• Cranes, hoists, hard-start conveyors: the HD rating and overload capacity are sized for shock loads.
• Modular integration: SM-option slots add Profibus, CANopen, DeviceNet, feedback cards and onboard SM-Applications logic.

How Unidrive SP differs from a plain VFD

The takeaway is simple: SP wins where you genuinely need servo or a tight closed loop. For an ordinary pump or fan it is overkill — pricier and dated.

When Unidrive SP is NOT the right choice

• A new pump, fan or conveyor without servo dynamics — pick a modern frequency inverter, such as Veichi AC310 or AC10.
• You need onboard fieldbus without add-on modules — SP requires an SM option.
• Single-phase 220 V supply — every model in this lineup is 3-ph/380 only.
• Guaranteed long-term spares — for greenfield builds specify Unidrive M700/M701.

Our experience with Unidrive SP

In practice most SP enquiries are about replacing a drive on a running machine where the engineer wants to keep the parameters and logic. Here we usually recommend the M701: it accepts the SP SMARTCARD parameter set and mirrors the control terminals, so the upgrade goes far more smoothly than rebuilding the whole panel. For a genuinely new task we steer customers honestly toward current series, because paying for a legacy platform there makes no sense.