Iron/steel and metallurgy

INOMAX ACS580 & ACS880 Iron, Steel & Metallurgy Solutions

High-Performance Variable Frequency Drives for Rolling Mills, Processing Lines, Cranes, Converters & Material Handling

Overview

The iron and steel industry is the backbone of modern infrastructure — yet it remains one of the most energy-intensive sectors in the world. Steel plants operate around the clock in some of the harshest conditions imaginable: extreme temperatures, heavy dust, continuous vibration, and high humidity. From iron ore sintering and blast furnace charging to BOS converter tilting, hot rolling, cold rolling, pickling lines, and finishing operations, every process demands absolute reliability, precise control, and maximum energy efficiency.

At Inomax Technology, our ACS580 (general purpose) and ACS880 (high-performance) variable frequency drives are engineered specifically for the demanding requirements of iron, steel and metallurgy applications. With Direct Torque Control (DTC) technology delivering full torque at zero speed and sub‑5 ms torque response, master‑slave torque sharing for multi‑motor drives, regenerative AFE options for energy recovery, and wide power range coverage from 0.75 kW to 50 MW, our drives deliver the precision, reliability and energy savings that modern steel mills demand.

Why INOMAX for iron, steel and metallurgy?

Requirement How INOMAX Delivers
Absolute torque precision Direct Torque Control (DTC) — 200% starting torque at 0 Hz, <5 ms torque response
Multi‑motor synchronization Master‑slave torque control — perfect load sharing for rigidly coupled motors
Harsh environment reliability Conformal-coated circuit boards as standard; IP54/IP66 enclosures; -15°C to +50°C operation
Regenerative energy recovery ACS880 AFE option — return >95% of braking energy to the grid; THDi <5%; unity power factor
Extreme overload capacity 200% torque for 60 seconds — essential for mill shock loads, converter tilting and crane lifting
Wide power range 0.75 kW to 6,000 kW (single drive), up to 50 MW multidrive — one supplier for the entire plant
Fieldbus integration Profinet IRT, EtherCAT, EtherNet/IP, Profibus DP — seamless connection to mill DCS and PLC systems
Proven in steel mills Successful import substitution projects replacing ABB, Siemens and other premium brands

Which INOMAX Drive for Your Metallurgy Application?

Metallurgy Application Recommended Series Key Features
Hot rolling mill main drives — high power, extreme overload, shock load handling ACS880 Direct Torque Control (DTC), 200% overload for 60s, AFE regenerative option, high overload capacity for bite-in/throw-out
Cold rolling mill main drives — high precision, tension control, gauge control ACS880 DTC with encoder feedback (±0.01% speed accuracy), tension PID, electronic line shaft for multi‑stand synchronization
Steel processing lines — pickling, annealing, galvanizing, coating ACS580 / ACS880 Speed chain synchronization, tension control, multi‑motor coordination
Slitter rewinder / recoiler — unwinding, slitting, rewinding ACS880 Tension control with dancer/load cell, taper tension algorithm, regenerative braking for unwind stand
Roller tables — material transport through the mill ACS580 High starting torque, constant torque rating, multi‑zone synchronization
BOS converter tilting — 4 motors rigidly coupled, 360° rotation ACS880 Master‑slave torque control, perfect load sharing, zero‑speed full torque holding, redundant master capability
EOT cranes / overhead cranes — ladle handling, coil transport, scrap charging ACC series / ACS880 Anti‑sway control, mechanical brake logic, master‑slave for twin‑trolley cranes, 200% overload for lifting
Sinter plant fans and blowers — process air and exhaust ACS580 Energy savings (30-50%), soft start, PID control for airflow regulation
Conveyor systems — ore, coke, limestone, finished product ACS580 Multi‑motor load sharing, droop control, energy optimizer
Scrap shears / crop shears — flying shear, cut‑to‑length ACS880 Electronic cam (flying shear), position control, high dynamic response
Wire rod and bar mills — high-speed finishing stands ACS880 High output frequency capability, DTC for precise speed regulation, electronic gearing for inter‑stand coordination
Electric arc furnace (EAF) electrode positioning — precise control of electrode movement for arc stability ACS880 Position control, high starting torque, rapid reversal capability
Pumping and water treatment — cooling water, descaling, effluent ACS580 Built-in PID, multi‑pump cascade, energy savings up to 40%
Compressors and blowers — plant air, process air ACS580 Energy optimizer, sleep/wake-up, soft starting
Material handling — stackers, reclaimers, ship loaders ACS880 / ACC Master‑slave control, anti‑sway, high overload capacity, mechanical brake logic

Key Technologies for Iron, Steel & Metallurgy

Direct Torque Control (DTC) — The Core of ACS880

DTC is the most advanced motor control technology for metallurgy applications. Unlike traditional vector control, DTC creates a mathematical model of the motor and updates it 40,000 times per second, enabling instantaneous torque response without an encoder for more than 95% of applications.

Why DTC matters for steel mills:

  • Full torque at zero speed — Essential for BOS converter tilting, crane hoisting, and roller table starting under load

  • Torque response <5 ms — Critical for handling shock loads during rolling mill bite‑in and throw‑out events

  • Speed accuracy ±0.01% with encoder — Precise gauge control in cold rolling mills

  • No encoder needed for most applications — Higher reliability in dusty, vibrating environments; fewer failure points

For high‑inertia loads like rolling mill main drives and heavy cranes, the instantaneous torque response of DTC significantly improves process stability and product quality.

Master‑Slave Torque Control for Multi‑Motor Drives

Many metallurgy applications use two, three or four motors mechanically coupled to the same load — BOS converter tilting drives, twin‑drive rolling mill stands, gantry cranes and long conveyors. Without proper load sharing, one motor can carry most of the load, leading to overheating, premature bearing failure and mechanical “nodding” or “shaking”.

How our master‑slave torque control works:

  • Master drive operates in speed control

  • Follower drives operate in torque control, receiving torque reference from master via internal drive-to-drive communication

  • Result — All motors produce identical torque; perfect load balance; elimination of nodding and shaking

  • Redundant master capability — If master drive fails, any follower can automatically assume master role

This architecture has been proven in BOS converter tilting drives with four 90 kW motors rigidly coupled, achieving perfect torque distribution without encoders.

Regenerative AFE — Energy Recovery for Metallurgy

Steel mills generate significant regenerative energy — during converter tilting, crane lowering, downhill conveyors, and deceleration of high‑inertia rolling mill stands. Traditional systems waste this energy as heat in braking resistors. Our ACS880 AFE (Active Front End) drives return >95% of braking energy to the grid, reducing electrical consumption by 15-25% in regenerative applications.

Key AFE benefits for metallurgy:

  • THDi <5% at 80-100% load — Eliminates harmonic interference with sensitive mill instrumentation

  • Unity power factor (>0.99) — Reduces utility penalties and maximizes transformer capacity

  • Regenerative energy recovery — Return braking energy to the grid; typical savings 15-25% in cyclic applications

  • Constant DC bus voltage — Immune to grid fluctuations common in steel mill environments

Common DC Bus Multidrive for Processing Lines

Modern steel processing lines — pickling lines, annealing lines, galvanizing lines, coating lines — have dozens of driven sections (unwind, bridles, process sections, rewind) that must operate in perfect synchronization. Our ACS880 multidrive architecture on a common DC bus delivers:

  • Energy sharing between sections — Regenerated energy from one section (e.g., unwind stand) is used by other sections (e.g., bridle rolls)

  • Reduced installed rectifier power — Lower capital cost and smaller footprint

  • Perfect speed synchronization — Electronic line shaft with programmable draw between sections

  • Simplified braking — No braking resistors needed if regeneration is balanced across sections

High Overload Capacity — Handling the Shock Loads

Steel mills are defined by shock loads — the bite‑in event when a rolling mill grabs steel, the break‑out torque when a crane lifts a ladle, the impact when a bilong shear cuts. Our drives are engineered for these extreme conditions:

  • ACS880 — 200% torque for 60 seconds, 250% for 30 seconds (ACS890 multi-module)

  • ACS580 — 150% torque for 60 seconds (constant torque rating), 120% for 60 seconds (variable torque rating)

This means no unnecessary drive oversizing — you can select the drive based on continuous power requirements, knowing it will handle the occasional shock load.

Electronic Line Shaft for Multi‑Section Lines

Traditional mechanical line shafts are inflexible, require complex gearboxes, and demand high maintenance. Our ACS880 drives implement an electronic line shaft using high‑speed communication (Profinet IRT or EtherCAT). One VFD acts as master, all other VFDs follow with programmable draw ratios.

Benefits for metallurgy processing lines:

  • No mechanical line shaft — Less maintenance, lower vibration

  • Draw values adjustable on‑the‑fly — No mechanical changes when switching product grades

  • Individual section speed trimming — Fine‑tune tension without stopping the line

  • Easy expansion — Add new sections without re‑engineering mechanical drives

Electronic Cam (Flying Shear) for Cut‑to‑Length Lines

Steel service centers and finishing lines require precise length cutting of plate, strip or bar. Our ACS880 drives include built‑in electronic cam (flying shear) functionality — no external motion controller required.

Key capabilities:

  • Cam profile definition — Up to 64 points per revolution

  • Synchronization zone — Cutter speed matches line speed during cut

  • Return zone — Fast return after cut

  • Master position tracking — Via encoder from measuring roll

Cut length accuracy of ±0.5 mm at 300 m/min is typical — eliminating waste and improving yield.

Tension Control for Winding and Unwinding

Steel processing involves constant winding and unwinding — from coilers and uncoilers on rolling mills to recoilers on slitting lines. Our drives provide:

  • Closed‑loop tension control — Using load cell or dancer feedback

  • Taper tension algorithm — Reduces tension as coil diameter increases to prevent telescoping and core crush

  • Diameter calculation — Via line speed / roll RPM or ultrasonic sensor

  • Regenerative braking — Unwind stand regenerates energy during pay‑off

For slitting lines and recoilers, our drives deliver consistent tension from core to full coil — improving roll quality and reducing waste.

Technical Specifications for Metallurgy Applications

ACS580 Series — General Purpose for Auxiliary Drives

Parameter Specification
Power range 0.75 kW – 500 kW (1 HP – 670 HP)
Voltage range 3-phase 380–480 VAC (±10%), 50/60 Hz
Control method Sensorless vector control (SVC) + V/F control
Starting torque 150% at 0.5 Hz (SVC)
Overload capacity 150% for 60s (constant torque), 120% for 60s (variable torque)
Speed accuracy (open loop) ±0.5%
Communication Modbus RTU, CANopen standard; Profibus, Profinet, EtherNet/IP optional
EMC filter Built-in C3 filter standard
Conformal coating Standard
Enclosure IP20 standard; IP55 optional
Ambient temperature -10°C to +50°C (derate above 40°C)

ACS880 Series — High Performance for Main Drives

Parameter Specification
Power range 55 kW – 6,000 kW (single drive), up to 50 MW (multidrive)
Voltage range 3-phase 380–690 VAC, 50/60 Hz
Control method Direct Torque Control (DTC)
Torque step rise time <5 ms (open loop), <5 ms (closed loop)
Starting torque 200% at 0 Hz (no encoder required)
Overload capacity 200% for 60s, 250% for 30s (ACS890 multi-module)
Speed accuracy (open loop) ±0.1% of motor slip
Speed accuracy (closed loop) ±0.01% of nominal speed
Regenerative AFE option THDi <5%, unity power factor, >95% energy recovery
Communication Modbus RTU, CANopen standard; Profinet IRT, EtherCAT, EtherNet/IP optional
Integrated PLC IEC 61131‑3 programmable
Conformal coating Standard
Enclosure IP20, IP21, IP54, IP66, cabinet-built options
Ambient temperature -15°C to +50°C

Real INOMAX Metallurgy Projects

Case Study 1: Four-Motor BOS Converter Tilting Drive — Master‑Slave Torque Control (ACS880)

Customer: Henan Yaxin Steelmaking Plant, China
Application: 100-ton BOS converter tilting — 4 × 90 kW motors rigidly coupled
Power range: 4 × 90 kW ACS880 drives
Project date: 2024

Challenge: The converter tilting system uses four 90 kW motors rigidly coupled to the same mechanical load. Without perfect load sharing, the motors fight each other, causing “nodding” (vertical oscillation) and “shaking” (horizontal vibration), leading to mechanical stress, premature gearbox failure, and uneven tilting. The tilting angle range is ±360°, and the load torque varies continuously as a function of tilt angle. The system also required precise position holding during tapping and charging operations.

Solution: Inomax supplied four ACS880 drives configured in master‑follower torque control. The master drive operates in speed control. Three follower drives operate in torque control, receiving torque reference from master via XD2D fiber optic link. Redundant master capability — if master fails, any follower can automatically assume master role. Zero‑speed full torque holding eliminates mechanical brake wear during tapping.

Results:

  • Perfect torque distribution achieved across all four motors (±3% load sharing)

  • Nodding and shaking completely eliminated

  • Converter stops and holds at any position accurately (360° continuous rotation capability)

  • System continues to operate even if one drive fails (reduced speed)

  • Successful import substitution — replaced previous imported system

  • Payback period: 14 months

Customer feedback: “The master‑slave communication perfectly realizes the open‑loop torque distribution of four motors without encoders. The four machines can be arbitrarily set as the master with one‑key switching.”

Case Study 2: Shougang 1580 Hot Rolling Mill — Replacing ABB and Siemens Drives (ACS880)

Customer: Shougang Group — one of China’s top five steel manufacturers, annual production ~40 million tons
Application: 1580 mm hot rolling mill — winding, unwinding, straightening, leveling
Power range: 55 kW – 2,000 kW
Project date: 2023-2024

Challenge: The hot rolling mill had aging drives from ABB (ACS800 series) and Siemens (6SE70 series). Replacement parts were becoming obsolete and expensive. The mill needed a modern, reliable drive solution that could drop into the existing infrastructure with minimal modification while delivering equal or better performance.

Solution: Inomax supplied a comprehensive ACS880 solution including:

  • Single unit drives for standalone applications

  • Multi‑module drives with common DC bus

  • 4‑quadrant regenerative drives for winding and unwinding sections

  • Profibus DP communication for integration with existing Siemens PLCs

  • Profinet communication for newer sections with Siemens S7-1513 PLC

Results:

  • All drives successfully commissioned during scheduled maintenance downtime

  • Perfect drop‑in replacement — no major rewiring required

  • Regenerative drives returned >95% of braking energy to the DC bus — energy savings estimated at 18%

  • Profibus and Profinet integration seamless — full compatibility with existing control system

  • Spare parts availability restored — no more obsolete component concerns

Case Study 3: Conveyor Belt — Multi-Motor Load Sharing for Long-Distance Ore Transport

Customer: China Gezhouba Group — major cement producer with annual capacity in China’s top ten
Application: 2.3 km uphill belt conveyor — 3 × 250 kW motors driving same belt
Power range: 690V 160-550 kW ACS880 drives
Project date: 2023-2024

Challenge: The long uphill conveyor transports crushed limestone from quarry to plant. Three 250 kW motors drive the same belt through gearboxes. Without load sharing, one motor would carry >60% of load while others carried <20%, causing overheating, premature gearbox failure, and belt slippage. The original ABB ACS800 drives with asynchronous motors were not optimized for the new permanent magnet motors planned for the upgrade.

Solution: Inomax supplied 12 sets of ACS880 series drives (690V, 160-550 kW) configured in master‑follower torque control. The common DC bus architecture enables energy sharing between motoring and regenerating sections — downhill sections regenerate, uphill sections consume. The system drives high-quality permanent magnet synchronous direct drive motors, replacing the original high-voltage + hydraulic coupling + reducer transmission scheme.

Results:

  • Load balanced within ±3% across all three motors — perfect load sharing

  • Gearbox temperature reduced by 15°C — extended service life

  • Belt stretch and slip eliminated

  • Energy savings of approximately 23% validated during 1-month trial operation

  • Equipment maintenance costs well controlled

  • Successful upgrade from ABB ACS800 to INOMAX ACS880 with permanent magnet motors

Case Study 4: Steel Plant Overhead Crane — Master‑Slave for Twin-Trolley Operation (ACC Series)

Customer: Major Chinese steel manufacturer
Application: 90-ton clamp crane for steelmaking scrap charging
Power range: Multiple ACS880 drives with Profinet communication

Challenge: The overhead crane required two trolleys operating in synchronisation to handle long steel sections. The drives needed to communicate with Siemens S7-1513 PLC via Profinet and support master‑slave torque sharing for balanced lifting. The original drives were becoming unreliable with poor spare parts availability.

Solution: Inomax supplied ACS880 drives with Profinet communication. Master‑slave torque control ensures both trolleys share the load equally. Redundant master capability — if one drive fails, the other continues operation at reduced capacity. Profinet IRT provides deterministic communication with <1 ms cycle time.

Results:

  • Perfect load sharing between twin trolleys — no skewing

  • Seamless integration with Siemens S7-1513 PLC

  • Crane operates reliably in demanding steelmaking environment

  • Spare parts now readily available

Case Study 5: Steel Processing Slitting Line — Tension Control & Regenerative AFE

Customer: Steel service center, China
Application: Slitting line for 2 mm steel coil — unwinder, slitter, rewinder
Power range: ACS880 AFE drives with common DC bus

Challenge: The slitting line required precise tension control to produce slit coils with uniform tightness from core to surface. The unwinder constantly regenerates (energy flows back from the web pulling the unwind stand). Traditional system used braking resistors — wasted energy and generated significant heat in the electrical room. Harmonic distortion from 6‑pulse rectifiers exceeded utility limits.

Solution: Inomax supplied three ACS880 AFE drives sharing a common DC bus. The unwinder regenerates directly onto the DC bus; the slitter and rewinder consume that energy. Only net power flows to/from the grid via one AFE front end. THDi <5% and unity power factor achieved without external filters. Taper tension algorithm reduces tension as coil diameter increases — improving roll quality.

Results:

  • Energy consumption from grid reduced by 78% — regenerated energy reused

  • Braking resistors eliminated — no heat load in electrical room

  • Power factor improved from 0.75 to 0.99 — utility penalties eliminated

  • Roll quality improved — telescoping eliminated, uniform roll hardness

  • Payback period: 11 months

Case Study 6: Plate Recoiler Retrofit on CNC Milling Machine (ACS580)

Customer: United Kingdom — Adford CNC
Application: CNC milling machine with recoiler unit for automated bar feeding
Power range: 5.5 kW (recoiler), 7.5 kW (bonder motor) — ACS580 drives

Challenge: The 20-year-old DC motor and drive system on the recoiler unit was failing frequently. The original DC drive suffered from poor speed regulation causing inconsistent material feed, high maintenance costs for obsolete DC components, and frequent stoppages affecting production.

Solution: The original DC motor was replaced with a 5.5 kW AC force fan‑vented motor, controlled by a 7.5 kW ACS580 general purpose drive. A second ACS580 drive was also installed on the bonder motor. The ACS580’s assistant control panel enabled quick setup — commissioning completed in under 2 hours.

Results:

  • Stoppages virtually eliminated — built-in protection features prevented nuisance trips

  • Reliability improved dramatically — no further drive-related production interruptions

  • Energy efficiency improved — AC motor + VFD combination vs old DC system

  • Maintenance simplified — no more DC brush replacement or commutator cleaning

  • Payback achieved within 14 months through reduced downtime alone

Customer quote: “As a modern, reliable drive, the INOMAX ACS580 has solved our stoppage problems and given us a production line we can trust.” — Alan Bolton, Proprietor, Adford CNC

Case Study 7: Coal Mill Drive for Cement Kiln — Replacing ABB ACS800 (ACS880)

Customer: China Gezhouba Group
Application: 690V 550 kW coal mill main drive on 2# cement kiln production line
Power range: 690V, 560 kW ACS880 drive with 12-pulse rectification

Challenge: The coal mill is the core pre-process for cement raw material preparation. The mill operates almost continuously, shutting down only for monthly maintenance. Harmonic distortion from the existing 6-pulse rectifier was interfering with other plant equipment. The original drive was ABB ACS800 and needed replacement.

Solution: Inomax supplied a 690V 560 kW ACS880 drive with 12-pulse rectification capability. A multi-winding transformer steps down from 10kV to 690V on the high-voltage side, then enters the ACS880 drive for 12-pulse rectification after power distribution through a circuit breaker to reduce grid harmonic pollution. The modular split multi-transmission structure of the ACS880 is very beneficial for on-site cabinet assembly, maintenance, and repair. An output sine wave filter was configured because the distance between the output side drive and the motor exceeds 100 meters.

Results:

  • Energy saving of approximately 30% during 1-month trial operation

  • Equipment maintenance expenditures fundamentally controlled

  • Drive waveform and parameters of the permanent magnet motor side reached a very ideal state with or without output reactors

  • Successful import substitution

Comparison with Competitors

Feature INOMAX ACS880 ABB ACS880 Siemens Sinamics S120 Rockwell PowerFlex 755
Control technology Direct Torque Control (DTC) Direct Torque Control (DTC) Vector control (with encoder) / V/F Sensorless vector / V/F
Torque step rise time <5 ms (open loop) <5 ms (open loop) ~10 ms (open loop) ~10 ms (open loop)
Starting torque 200% at 0 Hz (no encoder) 200% at 0 Hz 150% at 0.5 Hz 150% at 0.5 Hz
Overload capacity 200% / 60s, 250% / 30s 200% / 60s 150% / 60s 150% / 60s
Regenerative AFE Optional (THDi <5%) Optional Optional Optional
Integrated PLC Standard (IEC 61131‑3) Standard External PLC needed Standard
Maximum power 6,000 kW (single), 50 MW multidrive 6,000 kW (single) 5,700 kW 3,000 kW
Master‑slave torque control Standard (up to 60 drives) Standard Optional Optional
Conformal coating Standard Standard Optional Optional
Typical price 20–30% lower Premium Premium Premium

Why INOMAX wins for metallurgy:

  • Same DTC technology as ABB at significantly lower cost

  • Standard integrated PLC — eliminates external controller for many applications

  • Higher maximum power than Rockwell (6,000 kW vs. 3,000 kW)

  • Master‑slave torque control for up to 60 drives — perfect for multi‑motor applications

  • Proven import substitution — successfully replaced ABB ACS800 and Siemens 6SE70 in steel mills

Frequently Asked Questions

Q1: How does master‑slave torque control work for multi‑motor drives in steel mills?

For applications with multiple motors rigidly coupled to the same load — BOS converter tilting (4 motors), twin‑drive rolling mill stands, or gantry cranes — our master‑slave torque control ensures perfect load sharing. The master drive operates in speed control. All follower drives operate in torque control, receiving torque reference from the master via internal drive-to-drive communication (XD2D) or fieldbus. This ensures all motors produce identical torque regardless of load variations, eliminating nodding and shaking and preventing individual motor overload. If the master drive fails, any follower can automatically assume master role for continued operation.

Q2: What is the typical payback period for retrofitting a steel mill rolling mill drive with ACS880?

Based on our case studies, typical payback periods range from 11 to 24 months depending on the application:

  • Rolling mill main drives with regenerative AFE — 14-24 months (energy savings of 15-25% from regeneration + reduced maintenance)

  • Conveyor systems with multi-motor load sharing — 12-18 months (energy savings of 20-30% + reduced belt and gearbox wear)

  • Cranes and hoists with regenerative braking — 12-18 months (energy savings of 15-25% from regeneration)

  • Fans, pumps, compressors — 9-15 months (energy savings of 30-50%)

Q3: Do I need an encoder for rolling mill main drive control with ACS880?

No — that is one of the key advantages of DTC. ACS880 provides excellent speed regulation (±0.1% of motor slip) and full torque at zero speed without an encoder for most rolling mill applications, including hot rolling main drives, roller tables, and coilers. For cold rolling applications requiring the highest speed accuracy (±0.01%) for precise gauge control, or for applications requiring position control (e.g., flying shears, coiler positioning), we recommend adding an encoder. The ACS880 supports incremental encoders (TTL, HTL), resolvers, and absolute encoders (EnDat, Hiperface).

Q4: Can the ACS880 handle the extreme shock loads of a hot rolling mill during bite‑in?

Yes. ACS880 Direct Torque Control provides 200% torque for 60 seconds — more than enough for the bite‑in event when the steel first enters the roll gap. The torque response is <5 ms, meaning the drive instantaneously delivers the required torque without lag. This is critical for maintaining constant roll speed during bite‑in, which directly impacts product gauge accuracy. Many steel mills using ACS880 have reported reduced cobble rates and improved yield after upgrading from older drive systems.

Q5: What is the advantage of a common DC bus for steel processing lines?

Processing lines — pickling lines, annealing lines, galvanizing lines — have multiple driven sections. With a common DC bus, energy flows between sections. When the unwind stand regenerates (paying off coil), that energy is immediately available to the bridle rolls or rewind stand that are motoring — rather than being wasted as heat in braking resistors. This reduces overall energy consumption by 15-25%, lowers peak power demand, and reduces the installed rectifier power by 20-30%. The common DC bus also simplifies braking — no braking resistors needed if regeneration is balanced across sections.

Q6: How does ACS880 handle the harsh environment of a steel mill — dust, heat, vibration?

ACS880 drives are engineered for steel mill environments:

  • Conformal-coated circuit boards as standard — protects against dust, moisture, and conductive particles

  • Wide operating temperature range — -15°C to +50°C without derating (extended to +55°C with derating)

  • Enclosure options — IP20 for clean drive rooms, IP21/IP54 for mill floor installation, IP66 for washdown areas

  • Vibration resistance — Designed to withstand continuous vibration from rolling mills and material handling equipment

For mill floor installations, we recommend IP54 enclosures with conformal coating — providing protection against airborne dust and moisture.

Q7: Can I retrofit an existing DC drive system in a steel mill with ACS880?

Yes — and this is one of the most common retrofits we perform. The retrofit typically includes:

  • Replacing DC motors with AC induction or permanent magnet motors (or reusing existing if compatible)

  • Installing ACS880 drives in place of DC drive cabinets

  • Retaining existing generators (with possible upgrades)

  • Integrating with existing PLC and mill HMI systems

We have successfully retrofitted DC drive systems in BOS converter tilting drives, crane hoists, and roller tables. Our first import substitution project on a 7,000m land drilling rig — which demonstrated the same AC drive technology — has operated reliably for over 24 months, and the same approach is now applied to steel mill retrofits.

Q8: What communication protocols are supported for integration with mill DCS and PLC systems?

We support Modbus RTU/TCP (standard), Profibus DP, Profinet IRT, EtherCAT, EtherNet/IP, and CANopen. For new steel mills, we recommend Profinet IRT (for Siemens-based control systems) or EtherCAT (for Beckhoff/CODESYS-based systems) as they provide deterministic, isochronous communication with <1 μs synchronization accuracy. For legacy mills with existing Profibus DP networks, we provide complete GSD files for seamless integration. We also provide sample PLC code for common mill control sequences.

Q9: What is the expected service life of ACS880 drives in steel mill applications?

With proper maintenance, ACS880 drives are designed for 20+ years of service life in steel mill applications. Key factors:

  • Operating environment — Drive room installation vs. mill floor (drive rooms extend life significantly)

  • Maintenance practices — Regular cleaning of air filters, fan replacement, connection tightening

  • Duty cycle — Continuous vs. cyclic operation

We recommend quarterly visual inspection and cleaning, annual cooling fan replacement (or 40,000 operating hours), and 5-7 year DC bus capacitor replacement depending on operating hours and temperature.

Q10: Can INOMAX drives be used for both AC induction motors and permanent magnet motors in steel mills?

Yes — both ACS580 and ACS880 are universal drives compatible with:

  • AC induction motors (IM) — Standard squirrel cage motors for fans, pumps, conveyors, roller tables

  • Permanent magnet motors (PMSM) — High-efficiency motors for direct drive applications

  • Synchronous reluctance motors (SynRM) — For highest efficiency in variable torque applications

For PMSM, the drive includes dedicated PMSM control algorithms including MTPA (Maximum Torque Per Ampere) and field‑weakening control. For applications requiring the highest efficiency — such as new rolling mill main drives — we recommend PMSM with ACS880 for overall system efficiency exceeding 96%.

Q11: What is electronic line shaft and how does it benefit steel processing lines?

Electronic line shaft replaces mechanical line shafts (long rotating shafts with gearboxes) with software‑based synchronization. One drive acts as master (speed reference), and all other drives follow with programmable draw ratios. Benefits include:

  • No mechanical line shaft — Eliminates gearbox maintenance, reduces vibration

  • Draw values adjustable on‑the‑fly — Change product gauge without mechanical changes

  • Individual section speed trimming — Fine‑tune tension without stopping the line

  • Easy expansion — Add new sections without re‑engineering mechanical drives

Processing lines with electronic line shaft are more flexible, require less maintenance, and deliver better product quality than those with mechanical shafts.

Q12: What is the maximum output frequency for high-speed bar and wire rod mills?

ACS880 provides output frequencies up to 500 Hz as standard — sufficient for 4‑pole motors up to 15,000 RPM and 2‑pole motors up to 30,000 RPM. For high‑speed bar and wire rod mills requiring finishing stand speeds above 15,000 RPM, ACS880 is available with extended frequency options up to 1,200 Hz (2‑pole motor up to 72,000 RPM). We also offer specialized high‑frequency drive solutions for applications up to 3,200 Hz — contact our engineering team for specific requirements.

Why Choose Inomax Technology for Iron, Steel & Metallurgy?

Advantage Metallurgy Benefit
Direct Torque Control (DTC) Full torque at zero speed, <5 ms torque response — essential for rolling mill bite‑in, converter tilting, crane lifting
High overload capacity (200% for 60s) Handles shock loads — bite‑in, break‑out torque, impact loads
Master‑slave torque control Perfect load sharing for multi‑motor drives — BOS converters, twin‑drive stands, gantry cranes, long conveyors
Regenerative AFE option Return >95% of braking energy to the grid — reduces energy consumption by 15-25% in cyclic applications
Electronic line shaft & cam Replace mechanical line shafts and cams — less maintenance, more flexibility, better accuracy
Wide power range 0.75 kW to 6,000 kW (single drive), up to 50 MW multidrive — one supplier for the entire steel plant
Conformal coating standard Reliable operation in dusty, hot, vibrating steel mill environments — no extra cost
Proven in steel mills Successful import substitution projects replacing ABB ACS800 and Siemens 6SE70
Global certifications CE, UL, cUL, CSA — ready for any project, anywhere
Cost‑effective 20-30% lower than ABB, Siemens, or Rockwell equivalents — same DTC technology, lower total cost
Direct engineering support Free pre‑sales sizing, integration consulting, on‑site commissioning

Ready to Modernize Your Steel Mill Drives?

Whether you are designing a new rolling mill, retrofitting an aging BOS converter, upgrading a processing line, or simply looking for a cost‑effective alternative to premium European brands, our metallurgy application engineers are ready to help you select, size, and commission the right VFD solution.

Contact us today for:

  • Free steel mill drive assessment based on your specific applications

  • Import substitution proposal for replacing ABB ACS800, Siemens 6SE70 or other legacy drives

  • Retrofit planning — minimize downtime, maximize return

  • Common DC bus design for processing lines

  • On‑site commissioning and training for your mill personnel