Product Description

Nidec Control Techniques MP350A4R — Mentor MP DC Drive | 350A | 125kW | 200HP | 480V | 4-Quadrant Regenerative | New Original In Stock

DC motors don't become obsolete just because the industry gravitated toward AC drives. In high-power applications — paper mills, steel rolling lines, large extruders, winding machines, test stands — a well-maintained DC motor with a modern digital drive delivers controlled torque and speed that is genuinely difficult to match with an AC alternative at the same cost. The challenge historically was the drive itself: older analog DC drives required specialist knowledge to commission, drifted over time, and offered none of the network integration that modern plant control systems expect.

The MP350A4R solves that problem. It's Control Techniques' fifth-generation DC drive — the Mentor MP platform — built around the same digital control core as their Unidrive SP AC drive. That heritage matters: the commissioning tools, the option module ecosystem, the parameter structure, and the communications architecture all reflect decades of AC drive refinement applied to a DC converter. A panel builder already familiar with Control Techniques products will find the MP350A4R immediately recognizable. An engineer migrating from a Mentor II installation will find that the physical footprint and power terminal layout are unchanged.

At 350A armature output, 125kW on a 480V supply, with full four-quadrant regenerative capability, the MP350A4R handles demanding continuous-duty industrial applications that would stress smaller drives.

✅ Genuine Nidec Control Techniques. New original. Ships worldwide via DHL / FedEx / UPS.

Technical Specifications

Parameter	Specification
Model Number	MP350A4R
Drive Series	Mentor MP — DC Thyristor Drive
Frame Size	2A
Max. Armature Current	350A continuous
Motor Power @ 480V	125 kW / 200 HP
Max. Field Current	20A (standard internal controller)
Supply Voltage Range	24V to 480V AC (–20% / +10%)
Quadrant Operation	4-quadrant regenerative
Overload Capability	150% for 30 seconds (up to 10 times/hr at 40°C)
Cooling	Forced cooled (internal fan)
IP Rating	IP10 (Frame 2A)
Operating Temp (no derate)	0°C to 40°C
Operating Temp (with derate)	0°C to 55°C
Storage Temperature	–40°C to 55°C
Altitude	1,000m no derate; 1,000–3,000m: 1% per 100m
Humidity	95% non-condensing at 40°C
Pollution Degree	2 (dry, non-conducting)
Dimensions (H × W × D)	640 × 495 × 301 mm / 25.20 × 19.49 × 11.85 in
Weight	38 kg / 83.8 lb
Option Module Slots	3 universal option slots
On-Board PLC	6kB user program memory
Control I/O	3× analog in, 2× analog out, 3× digital I/O, 4× digital in, 2× N.O. relay (250V AC max)
Analog Input Resolution	Input 1: 14-bit + sign; Inputs 2 & 3: 10-bit + sign
Operating Modes	Estimated speed (open loop), tacho feedback, encoder feedback
Communications (via options)	RS485, Ethernet, EtherCAT, PROFIBUS, DeviceNET, CANopen, Interbus
Certifications	CE, cUL (USA/Canada), KC (Korea), RCM (Australia/NZ), EAC
Warranty	5 years standard
Product Safety Standard	EN61800-5-1
EMC Emission Compliance	Category C3 without filters; C2 with recommended filters/reactors

Four-Quadrant Operation — What It Means and Why It Matters

A DC drive's quadrant designation describes what it can do with power flow and direction of rotation. This is not an abstract classification — it determines whether the drive can handle certain types of loads and braking requirements.

Two-quadrant drives (no "R" suffix) handle forward motoring and can control current during deceleration, but they cannot feed energy back to the AC supply. Braking energy is typically dissipated as heat in a dynamic braking resistor.

Four-quadrant regenerative drives like the MP350A4R can motor in both directions AND return braking energy to the AC supply grid during deceleration. The thyristor bridge fires in a controlled sequence that reverses current flow, effectively running the drive as an inverter (in the AC sense) to push energy upstream. This has two practical consequences:

First, operating costs are lower in high-cycle or continuous braking applications. A winding machine that repeatedly accelerates and decelerates a large roll of material can recover substantial energy during each deceleration phase rather than burning it off in resistors. Second, braking performance is cleaner — the AC grid absorbs the energy instead of a resistor bank heating up, and the torque control during braking is as precise as during motoring because the same thyristor bridge handles both.

Applications that specifically need four-quadrant operation include: winders and unwinders with tension control, hoists and cranes with regenerative lowering, test stands that both drive and absorb load, large centrifuges, and any process where the motor frequently operates against its direction of rotation.

The Mentor MP Control Architecture

What distinguishes the Mentor MP from earlier generations of DC drives is not primarily the power electronics — a thyristor bridge is a mature technology. The differentiation is in the digital control platform, which Control Techniques developed from their Unidrive SP AC drive rather than building a DC-specific controller from scratch.

Three universal option module slots accept the same SM-series option modules used across Control Techniques' AC drive range. A communications module for PROFIBUS goes into a Mentor MP the same way it goes into a Unidrive M700. An encoder feedback module, an I/O expansion module, a machine control module with application programming — all available from the same module ecosystem. This matters for system integrators who are already familiar with one option module type: it transfers directly.

On-board PLC with 6kB of user program memory runs structured text or other IEC 61131-3 code directly in the drive. Simple sequencing logic, tension control algorithms, winder calculations — these can execute inside the MP350A4R without requiring a separate external controller for process logic.

CTSoft commissioning software connects via Ethernet, CTNet, serial, or USB. For engineers migrating from Mentor II, a built-in migration wizard transfers parameter sets to the Mentor MP format automatically. This is a meaningful time saving during retrofit projects where the Mentor II parameter set represents years of tuned application-specific adjustments.

Galvanic isolation between power and control circuits — documented as a patent-pending feature at the time of the Mentor MP's release — protects control circuits and any equipment connected to the drive's control terminals from the high voltages present on the power thyristor circuit. On a drive handling up to 480V AC input and hundreds of amps of DC output, this isolation is a genuine protection benefit rather than a marketing claim.

Field Control — Internal vs. FXMP25 External

Every MP350A4R includes an internal field controller as standard. For the majority of DC motor applications, this built-in controller provides complete field regulation, including intelligent field weakening for constant-power operation above base speed. The internal controller handles field currents up to 20A, which covers most industrial DC motors in the 125kW class.

Three situations call for the optional FXMP25 external field controller instead:

The motor requires more than 20A field current — typically older motors with low field voltage windings that draw higher current to achieve rated field flux. The FXMP25 extends field current capability to 25A and can be controlled digitally via RJ45 connection from the main drive.

The application requires forced field weakening faster than a standard half-controlled field bridge allows — spindle drives and motors with high field time constants where the field must collapse quickly for rapid speed range changes.

Field current reversal is needed without armature reversal — a specific four-quadrant technique applicable where rapid torque direction reversal isn't required but direction of rotation needs to change.

For standard industrial applications with motors in good condition and field windings within normal parameters, the built-in controller handles everything without the FXMP25.

Mentor MP Model Family at 480V — Size Reference

Model	Armature Current	Power (480V)	Frame	Quadrant
MP210A4R	210A	75 kW / 125 HP	1B	4Q Regen
MP350A4R	350A	125 kW / 200 HP	2A	4Q Regen
MP420A4R	420A	150 kW / 250 HP	2A	4Q Regen
MP550A4R	550A	200 kW / 300 HP	2A	4Q Regen
MP700A4R	700A	250 kW / 400 HP	2B	4Q Regen
MP350A4	350A	125 kW / 200 HP	2A	2Q only

The "R" suffix is the critical differentiator for regenerative applications. The MP350A4 (no R) uses the same frame, same armature current rating, and same physical dimensions but lacks the second anti-parallel thyristor bridge required for four-quadrant operation.

Typical Applications

The MP350A4R's 125kW / 350A / 4-quadrant rating places it in demanding industrial territory. Applications where this drive is commonly found:

Paper and printing — Winding, unwinding, and tension control on paper rolls require precise torque in all four quadrants. The regenerative capability allows controlled braking during deceleration without resistor banks, and the on-board PLC handles winder diameter compensation calculations.

Metal processing — Wire drawing, coil winding, and rolling mill auxiliary drives benefit from the high armature current rating and four-quadrant operation. DC motors on these applications often represent capital equipment that will run for decades; upgrading the drive to Mentor MP extends motor life rather than replacing the motor.

Test stands — Dynamometer and load simulation applications need to operate the connected machine as a generator as well as a motor. The MP350A4R absorbs energy from the device under test and returns it to the supply rather than wasting it in resistors.

Hoists and cranes — Regenerative lowering of heavy loads recovers energy that would otherwise be dissipated as heat. On high-cycle operations such as steel plant charging cranes, the energy savings accumulate to a meaningful operational cost reduction.

❓ FAQ — Nidec Control Techniques MP350A4R

Q1: What does the "R" suffix mean, and do I need it for my application?

The "R" suffix identifies four-quadrant regenerative operation, enabled by a fully controlled anti-parallel thyristor bridge configuration. It means the drive can both supply current to the motor (motoring) and receive current from the motor acting as a generator (braking), in both directions of rotation. If your application involves controlled deceleration of large inertia loads, bidirectional operation, active tension control, or hoist/crane duty where the load drives the motor during lowering, you need the "R" variant. Two-quadrant drives (MP350A4 without R) can still decelerate, but they do so by reducing armature current and allowing the load to coast, or through a dynamic braking resistor — not by feeding energy back to the AC supply. For applications with light braking duty and unidirectional operation, the non-R version may be sufficient and is slightly less expensive.

Q2: What supply voltage does the MP350A4R accept, and is it suitable for both 460V and 380V installations?

The "4" in the model number designates the 480V voltage class, with a supply range of 24V to 480V AC (–20% / +10%). This makes it compatible with 208V, 240V, 380V, 400V, 415V, and 460/480V three-phase supplies. The –20% tolerance on the lower end means even a nominal 380V supply dipping under load is acceptable. The +10% upper tolerance on 480V means a 528V supply condition would exceed the input rating. For 575V or 690V supplies, separate model variants exist (MP350A5R, MP350A6R) with different voltage class designators.

Q3: The datasheet lists IP10 protection for the Frame 2A size — what does IP10 mean for installation?

IP10 (also noted as NEMA 1 equivalent in some documentation) means the enclosure provides protection against solid objects greater than 50mm — essentially a finger-safe classification — but offers no protection against liquids. The Frame 2A Mentor MP is an open chassis drive intended for installation inside a control panel or equipment enclosure that provides the final environmental protection. It is not suitable for direct exposure to moisture, oil mist, conductive dust, or corrosive atmospheres. For installations in particularly harsh environments, the conformal-coated variant (MP350A4R-CC) provides additional protection for the electronics against humidity and mild chemical attack, but the IP rating of the enclosure itself remains the same — the control panel must provide the physical environmental protection.

Q4: How does the on-board 6kB PLC work, and what kinds of application programs can run in the drive?

The Mentor MP's on-board PLC executes user-written programs in the drive's own processor, independently of any external controller. The 6kB of program memory supports structured text code written in Control Techniques' SyPTPro or Drive Solutions Programmer software tools. Typical applications for on-board PLC programs include winder control with diameter compensation, tension regulation loops, sequential startup/shutdown sequences, and custom parameter manipulation. The advantage over external PLC control for these functions is speed: the on-board program executes at the drive's own task rate, giving direct access to drive parameters without the latency of a network transaction. For more complex machine logic, the SM-Applications Plus option module adds extended on-board processing capability.

Q5: Can the MP350A4R replace a Mentor II drive directly, and what is involved in the migration?

Yes — direct mechanical and power replacement is one of the design goals of the Mentor MP platform. The Frame 2A Mentor MP has the same physical footprint and the same power terminal connection positions as the equivalent Mentor II frame. Bolting the new drive into the existing panel and connecting the existing power wiring is mechanically straightforward. The control wiring requires verification because terminal assignments differ between generations. Control Techniques provides a free CTSoft migration wizard that reads a Mentor II parameter set and generates the equivalent Mentor MP parameter file, handling the translation of parameter numbers and scaling between the two platforms. This significantly reduces commissioning time compared to manual re-entry of a large parameter set. Any custom application programs in the Mentor II (if using Mentor II's application programming features) would need to be reviewed and adapted for the Mentor MP's on-board PLC environment.

Q6: What communications options are available, and how are they installed?

The MP350A4R has three universal option module slots that accept SM-series communications modules. Available communications options include SM-PROFIBUS, SM-Ethernet, SM-EtherCAT, SM-DeviceNET, SM-CANopen, and SM-Interbus. RS485 serial communication is built into the drive without requiring an option module. A single RJ45 connector on the drive provides Ethernet connectivity for CTSoft commissioning software. Option modules slide into the option slots and are recognized automatically by the drive firmware — no hardware configuration switches are involved. Multiple option modules can occupy different slots simultaneously, so a drive can have PROFIBUS for machine-level communication in slot 1, and SM-I/O Plus for expanded I/O in slot 2, running concurrently. The third slot can be held as a spare for future expansion.

Q7: What does the 5-year standard warranty cover, and how does it compare to other DC drive suppliers?

Nidec Control Techniques offers a 5-year standard warranty on the Mentor MP as part of their standard product terms — no registration required, no additional purchase needed. This covers manufacturing defects in materials and workmanship for the drive unit from the date of purchase. The 5-year term is notable in the industrial drive market, where 1–2 year warranties are more typical at this power level. This warranty position reflects the company's stated confidence in the Mentor MP's reliability and is explicitly highlighted in their product literature as a competitive differentiator. For OEM applications where long machine service intervals are expected, the warranty term reduces the total cost of ownership calculation compared to drives requiring earlier planned replacement or warranty purchases.

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