INOMAX ACS580 & ACS880 – Mine Hoist Solutions

High-Performance Variable Frequency Drives for Shaft Hoisting, Winder & Underground Transport

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Overview

Mine hoisting is one of the most critical and demanding applications in the mining industry. Whether it is a friction hoist (Koepe winder) or a drum winder (Blair or single-drum), the hoist system transports men, material, and ore up and down shafts that can extend thousands of meters underground. A failure or malfunction can halt production, endanger lives, and cost millions in lost output. The electric drive system must deliver absolute reliability, precise speed and torque control, high overload capacity for emergency braking and heavy loads, and regenerative braking to return energy to the grid during lowering.

At Inomax Technology, we supply ACS580 (general purpose) and ACS880 (high-performance) variable frequency drives to mine hoist OEMs, retrofit specialists, and mining operators worldwide. Our drives are engineered for the unique demands of mine hoisting: Direct Torque Control (DTC) with full torque at zero speed for precise positioning, regenerative AFE for energy recovery during lowering (saving 15-25% of hoisting energy), high overload capacity (200% for 60s) for emergency stops and heavy skip loads, master‑slave torque control for twin-drive hoists, and harsh environment protection with conformal coating and IP54/IP66 enclosures.

We are also actively expanding our global partner network. If you are a distributor, system integrator, mine hoist OEM, or retrofit specialist, we invite you to explore a partnership with INOMAX – factory‑direct pricing, technical support, market protection, and proven technology trusted by mining operations worldwide.

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Why Mine Hoists Need High-Performance VFDs

The Challenge – Safety, Reliability & Energy Efficiency

Mine hoists operate in some of the harshest conditions on earth: high humidity, conductive dust, temperature extremes, continuous vibration, and potential for explosive gas (methane). The drive system must be fail-safe – braking and emergency systems must work even if the main power fails. It must deliver precise positioning at the shaft top and bottom to within millimeters. And it must handle peak torque during acceleration and emergency stops.

Traditional DC drives (Ward-Leonard) are obsolete – inefficient, high maintenance, and poor speed regulation. Direct-on-line AC is impossible for large hoists. VFD-controlled AC drives are now the industry standard, offering higher efficiency (95%+), lower maintenance (no brushes/commutators), better speed regulation (±0.01% with encoder), and regenerative braking.

Energy Savings – Regenerative Lowering

When a loaded skip descends, the hoist motor regenerates energy. A non‑regenerative VFD wastes this energy as heat in braking resistors. Our ACS880 AFE regenerative drives return >95% of this energy to the grid, reducing overall hoisting energy consumption by 15-25%. For a deep mine with frequent hoisting cycles, this can save hundreds of thousands of dollars annually.

Precision Positioning – Full Torque at Zero Speed

At the shaft bottom and top, the hoist must stop within millimeters of the target to allow proper loading/unloading. Our DTC technology delivers full torque at zero speed without an encoder – the motor holds the skip exactly at the landing position without mechanical brake drag, enabling precise, repeatable positioning.

High Overload Capacity – Emergency & Dynamic Braking

Mine hoists must handle emergency stops and heavy overloads. Our ACS880 provides 200% torque for 60 seconds – sufficient for the most demanding hoisting cycles. The drive also includes dynamic braking via braking resistors or regenerative AFE.

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Key Technologies – Professional Solutions for Mine Hoists

1. Direct Torque Control (DTC) – Precision & Torque at Zero Speed

ACS880 DTC updates the motor model 40,000 times per second, delivering instantaneous torque response without an encoder for most hoisting applications.

Why DTC matters for mine hoists:

• Full torque at zero speed – The hoist holds the skip exactly at the landing position without mechanical brake wear; smooth, controlled starts from zero speed

• Torque response <5 ms – Critical for emergency stops and anti‑slip control during acceleration/deceleration

• Speed accuracy ±0.01% with encoder – Precise positioning at shaft top and bottom

• No encoder needed for most applications – Higher reliability in dusty, vibrating mine environments

2. Regenerative AFE (Active Front End) – Energy Recovery During Lowering

When a loaded skip descends, the motor acts as a generator, producing energy. Traditional drives waste this energy as heat in braking resistors. Our ACS880 AFE returns >95% of this energy to the grid.

Key AFE benefits for mine hoists:

• Energy recovery during lowering – 15-25% reduction in hoisting energy consumption

• THDi <5% at 80-100% load – Eliminates harmonic interference with mine communication and control systems

• Unity power factor (>0.99) – Reduces utility penalties and generator fuel consumption in off-grid mines

• Constant DC bus voltage – Immune to grid fluctuations common in remote mine sites

3. Master‑Slave Torque Control for Twin-Drive Hoists

Large mine hoists (especially friction hoists) often use two motors driving the same sheave or drum. Without proper load sharing, one motor can carry most of the load, leading to overheating and premature failure.

How our master‑slave torque control works:

• Master drive operates in speed control

• Slave drive operates in torque control, receiving torque reference from master via internal drive-to-drive communication

• Result – Both motors produce identical torque; perfect load sharing; eliminates “nodding” and “shaking”

• Redundant master capability – If master fails, slave can automatically assume master role

4. Mechanical Brake Control Logic – Integrated Safety

Mine hoists require coordinated control between the VFD and the mechanical brake. Our drives include dedicated hoist brake logic:

• Pre‑excitation before brake opening – Torque is established before the brake releases, preventing slip

• Programmable brake open/close delays – Matched to your brake system response time

• Zero-speed brake closing – Brake closes only after the motor reaches zero speed, minimizing wear

• Brake response monitoring – Optional feedback input confirms brake status

5. Anti‑Slip Control for Friction Hoists

Friction (Koepe) hoists rely on the coefficient of friction between the rope and the sheave. Excessive acceleration or deceleration can cause rope slip. Our drives include:

• Torque rate limiting – Prevents sudden torque changes that could cause slip

• Acceleration/deceleration profiling – Smooth S-curve ramps for rope-friendly operation

• Torque limit monitoring – Optional feedback from rope tension sensors

6. High Overload Capacity – Emergency & Dynamic Braking

Mine hoists must handle emergency stops and heavy overloads. Our ACS880 provides 200% torque for 60 seconds – sufficient for the most demanding hoisting cycles. The drive also includes dynamic braking via braking resistors or regenerative AFE.

7. Harsh Environment Protection – Built for Mines

Mines are among the harshest environments for electrical equipment: high humidity, conductive dust, vibration, and potential for explosive gas. Our drives feature:

• Conformal-coated circuit boards as standard – Protects against moisture and conductive dust

• IP54/IP66 enclosure options – For installation in underground or surface hoist houses

• Wide operating temperature range – -15°C to +50°C without derating (extended options available)

• Stainless steel hardware options for critical components

8. Fieldbus Integration for Mine Control Systems

Mine hoists are integrated with shaft signaling systems, conveyor control, and mine-wide SCADA. Our drives support all major protocols:

• Profinet IO / Profinet IRT – For Siemens-based mine control systems

• EtherNet/IP – For Rockwell-based systems

• EtherCAT – For high‑performance synchronization

• Profibus DP – For legacy mine systems

• CANopen – For many European hoist controllers

• Modbus RTU/TCP – For universal compatibility

We provide complete GSDML, ESI, and EDS files, plus sample code for common mine hoist controllers.

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Mine Hoist Types Covered

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Technical Specifications – Professional Grade

ACS580 Series (Smaller Service Hoists & Auxiliary Winders)

ACS880 Series – High‑Performance for Main Production Hoists

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Real Projects – Proof of Performance

Our drives are used by mine hoist OEMs, retrofit specialists, and mining operators worldwide. Customer names are partially hidden for privacy.

Measured results from these installations:

• Energy recovery during lowering: 15-25% reduction in hoisting energy consumption

• Positioning accuracy: ±5 mm at shaft bottom (with encoder feedback)

• Master‑slave torque balance (twin-drive hoists): within ±3%

• Drive availability: >99.5% in continuous 24/7 operation

• Brake wear reduction: estimated 30-50% (zero-speed brake closing)

• Payback period (energy savings only): 12-24 months

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For Distributors, System Integrators & Mining Specialists

Why Partner with INOMAX?

Partnership Models

Distributor Support Program

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Frequently Asked Questions

For End Users (Technical)

Q1: How much energy can I save by retrofitting my mine hoist with a regenerative ACS880 AFE drive?

When a loaded skip descends, the motor regenerates energy. A non‑regenerative drive wastes this energy as heat in braking resistors. Our ACS880 AFE returns >95% of this energy to the grid. For a typical deep mine hoist operating 20 cycles per hour, 8,000 hours/year, with 250 kW average lowering power, annual energy savings can exceed 1.5 million kWh – worth $150,000-$200,000 depending on electricity rates. Payback is typically 12-24 months from energy savings alone.

Q2: Can I use ACS880 without an encoder for precise hoist positioning?

Yes – DTC provides full torque at zero speed and ±0.1% speed accuracy without an encoder. For most hoisting applications, this is sufficient. For applications requiring ±0.01% speed accuracy or positioning within millimeters, we recommend adding an encoder. The ACS880 supports incremental encoders (TTL, HTL), resolvers, and absolute encoders (EnDat, Hiperface).

Q3: How does the mechanical brake logic work on ACS880?

Our drives include dedicated hoist brake logic. When a stop command is given, the drive decelerates the hoist to zero speed (using regenerative braking to save energy), then issues a brake close command. The brake closes after a programmable delay, and the drive continues to hold torque until the brake is fully engaged. When starting, the drive pre‑excites the motor and builds torque before opening the brake – preventing any slip. This sequence minimizes brake wear and ensures safe, smooth operation.

Q4: What is master‑slave torque control and when is it needed?

Large friction hoists often use two motors driving the same sheave. Without load sharing, one motor can carry most of the load. Master‑slave torque control ensures both motors produce identical torque – the master operates in speed control, the slave(s) in torque control receiving torque reference from the master. This eliminates uneven loading, reduces overheating, and extends motor and gearbox life.

Q5: Can ACS880 handle emergency stop and dynamic braking?

Yes. ACS880 provides 200% torque for 60 seconds – sufficient for emergency stops. For dynamic braking, you have two options: braking resistors (dissipate energy as heat) or regenerative AFE (return energy to the grid). For deep mines with frequent hoisting cycles, AFE is recommended for energy savings.

Q6: What certifications do INOMAX drives hold for mining applications?

Our drives are CE, UL, cUL, and CSA certified. For mining applications, we offer CCS (China Classification Society) and DNV type approvals. For hazardous area applications (gas/dust), we can supply drives with ATEX or IECEx certified enclosures (Ex d or Ex e). Contact us for specific requirements.

Q7: What is the expected service life of ACS880 drives in underground mine hoist houses?

With proper maintenance, 20+ years. We recommend IP54 enclosures for underground installations (protects against dust and humidity). Conformal coating (standard on all our drives) protects against conductive dust and moisture. Regular cleaning of air filters and annual fan replacement are essential.

For Distributors & Partners (Commercial)

Q8: What is the minimum order quantity (MOQ) for distributors?

No strict MOQ for initial orders. Volume discounts apply from 10 units per order. For OEM/private label, MOQ is negotiated.

Q9: What is the standard warranty period?

2 years from date of manufacture or 12 months from commissioning, whichever comes first. Extended warranty up to 5 years available.

Q10: What is your typical lead time?

Popular models (≤250 kW) – 3-5 working days from our China factory + shipping. Larger units (250-6,000 kW) – 2-4 weeks.

Q11: Do you offer market protection?

Yes. Exclusive territory agreements (subject to minimum commitment) and project registration. Registered projects are protected – we will not quote directly or work with other distributors on that project.

Q12: Can you customize drives for my OEM requirements?

Yes: private labeling, custom parameter presets for specific hoist types, special enclosures, modified firmware, custom voltage/frequency ranges.

Q13: What technical support can I expect for my customers?

Free pre-sales support: drive sizing, harmonic analysis, configuration recommendations, brake logic setup. Post-sales: remote diagnostics (free), on-site commissioning (fee-based). Product training for your technical staff.

Q14: How does INOMAX compare to ABB, Siemens or Danfoss for mine hoists?

We are legitimate competitors. Our ACS880 uses the same Direct Torque Control (DTC) technology as ABB ACS880. Performance specifications match or exceed competition. Price is 20-30% lower. Lead times are shorter. Customization is more flexible. Our hoist brake logic and master‑slave torque control are specifically designed for mine hoisting applications.

Q15: Do you offer retrofit kits for converting existing DC-driven mine hoists to AC VFD?

Yes. We offer pre‑engineered retrofit packages including:

• ACS880 AFE regenerative drive(s) sized for your hoist motor(s)

• Optional encoder kits

• Pre‑configured parameters for your hoist type (friction or drum, single or twin drive)

• Brake logic setup

• Wiring diagram and installation guide

• Commissioning checklist

Contact us with your hoist specifications for a quote.

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Ready to Partner with INOMAX?

Join a growing network of distributors, retrofit specialists, and mine hoist OEMs who have discovered that INOMAX delivers premium performance at a competitive price – with real factory support.

Apply for distributorship today:

• Fill out the form below with your company information and market focus

• We will contact you within 24 hours to discuss partnership terms

• Receive distributor pricing, marketing materials, and technical documentation