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The FR-F740-S75K-CHT is a 3-phase 400V-class inverter from Mitsubishi Electric’s FREQROL‑F700 series, designed specifically for fan and pump applications. Optimized for 75kW quadratic torque loads, it is a classic flagship model for industrial energy-saving speed control and fluid control systems, compliant with Chinese CCC certification and domestic power grid standards.
- Explicação do modelo
| Código | Descrição |
| França | General prefix for Mitsubishi FREQROL series inverters |
| F740 | F700 series, 3-phase 380~480V class, energy-saving model dedicated for fans and pumps |
| S75K | Applicable motor rating: 75kW three-phase induction motor; S indicates large-size heavy‑duty series |
| CHT | Version exclusive to Chinese market, adapted to local power grid, compliant with GB and CCC |
- Key Rated Electrical Specifications
| Item | Especificação |
| Applicable motor capacity | 75kW (three-phase induction motor) |
| Rated output capacity | 110kVA for both SLD / LD duty |
| Corrente de saída nominal | 144UM (common for SLD light duty / LD heavy duty) |
| Capacidade de sobrecarga | SLD default: 110% rated current for 60s, 120% for 3s at 40°C |
| LD heavy duty: 120% rated current for 60s, 150% for 3s at 50°C | |
| Both feature inverse-time characteristics | |
| Input power specification | 3-phase AC 380~480V, 50/60Hz; allowable voltage fluctuation: 323~528V, freqüência: ±5% |
| Faixa de frequência de saída | 0.2~400Hz, speed control range 1:100 (sob controle vetorial) |
| Protection structure | Open type IP00, must be installed in a qualified enclosure |
| Método de resfriamento | Resfriamento por ar forçado |
| Aprox.. weight | 35kg |
| Dedicated DC reactor | FR-HEL-H75K |
- Funções principais & Características
- Dedicated Energy-Saving Control
Optimized for quadratic torque loads such as fans and pumps. Built-in optimal excitation control and energy-saving mode achieve up to 30% higher energy efficiency than conventional V/F control.
- Multi-Mode Precision Control
Supports V/F control, advanced magnetic flux vector control, general vector control. Stable low-speed torque. Suitable for constant-pressure water supply, multi-pump systems, closed-loop temperature/airflow control. Dual PID and sleep/wake functions included.
- Alta confiabilidade & Full Protection
Proteção abrangente: sobrecorrente, sobretensão, subtensão, superaquecer, sobrecarga, prevenção de estol, falha à terra. Adaptive to power fluctuations. Designed lifetime of main capacitors and fans exceeds 10 anos.
- Rich Communication & Expansão
Standard RS485, Modbus-RTU. Link CC opcional, Profibus-DP, DeviceNet cards for seamless integration into automation systems.
- User-Friendly Design
Standard FR-DU07 keypad: local start/stop, frequency setting, parameter tuning, fault monitoring. Parameters compatible with Mitsubishi inverter series.
- Principais aplicações
Primary: 75kW 3-phase 380V fans, bombas, compressors — industrial water supply/drainage, central AC water circulation, boiler ID/FD fans, AVAC, water treatment aeration/booster systems.
Secondary: Transportadores, misturadores, equipamento de ventilação. Ideal for continuous operation requiring high efficiency, estabilidade, e longa vida útil.
- Instalação & Diretrizes de Comissionamento
- Instalação: IP00 open type must be installed in a proper enclosure, vertically mounted with sufficient cooling space. Ambient temp: -10~+50°C. Avoid moisture, pó, corrosive gas, strong EMI.
- Fiação: Main input R/L1, S/L2, T/L3 → power supply; output U, V, W → motor. Never reverse input/output. Use suitable circuit breakers and contactors. Recommended DC reactor FR-HEL-H75K to improve power factor and reduce harmonics.
- Modos de controle: PU (teclado), external terminal, comunicação. Perform motor auto-tuning first. Set acceleration/deceleration time, PID, and protection levels accordingly.
- Aterramento: Reliable independent grounding, resistance ≤10Ω. Do not share ground with high-power equipment.
- Typical Faults & Solução de problemas
| Código de falha | Descrição | Main Checks |
| EOC1 | Overcurrent during acceleration | Check if acceleration time is too short, motor short鈥慶ircuit/ground fault, or load jam |
| EOV | Main circuit overvoltage | Check high input voltage, short deceleration time, or improper braking circuit |
| EUV | Main circuit undervoltage | Check phase loss, loose input terminals, or excessive power fluctuation |
| OH | Inverter overheat | Check fan failure, blocked air duct, or excessive ambient temperature |
| OL | Sobrecarga do motor | Check motor stall, sobrecarga, or mismatched motor rated parameters |
Complete Guide to Braking Resistor Selection for Mitsubishi FR-F740-S75K-CHT
- Critical Pre-Selection Notes (Deve ler)
The FR-F740-S75K-CHT is a 75kW 3-phase 400V fan/pump inverter with no built-in braking transistor or braking unit. It cannot directly connect external braking resistors.
An external braking unit must be installed first, then matched braking resistors. De outra forma, permanent damage to the inverter main circuit will occur.
1.1 Typical Applications Requiring Braking Resistors
Fast motor deceleration / parar, much shorter than free-run time
High-inertia loads (large fans, bombas, centrífugas)
Frequent `EOV` DC bus overvoltage faults during deceleration
Precise speed control without overshoot
Continuous braking for hoisting / lowering applications
1.2 Recommended Braking Unit
Use genuine Mitsubishi or compatible units:
| Item | Genuine Model | Parâmetros principais |
| Unidade de freio | FR-BU2-H75K | For 75kW 400V-class inverter, max withstand voltage 800V DC, IP00, forced air cooling |
| Minimum allowable external resistance | 6.5Oh | Never use resistance lower than this value, otherwise IGBT will burn out |
| Genuine matching resistor unit | MT-BR5-H75K | Standard resistance 6.5Ω, adequado para 10% ED duty, built‑in overheat protection |
- Braking Resistor Selection Rules
Core parameters: resistência, rated power, voltage class.
2.1 Resistance (R)
Must be ≥ 6.5Ω
Practical range: 6.5Ω ~ 20Ω
2.2 Potência nominal (P)
Braking resistors are intermittent duty. Selection depends on ED% (duty ratio).
Genuine MT-BR5-H75K: 65kW, suitable for ED ≤10%.
2.3 Suportar Tensão & Tipo
Classe de tensão: ≥ 1000V DC
Preferred types:
- Corrugated stainless steel resistor — excellent heat dissipation, high overload
- Aluminum-housed resistor — compact, low duty
- Genuine MT-BR5 — plug-and-play, proteção térmica
- Duty-Based Selection Table
| Duty Level | Aplicação Típica | ED% | Recommended R | Recommended P | Notas |
| Light basic | Occasional stop, decel ≥30s, ≤10 starts per shift | ≤5% | 6.8Ω~10Ω | 7.5kW~10kW | Basic overvoltage protection only |
| Em geral | Normal fan/pump, frequent starts, decel 10~30s | 5%~10% | 6.5Ω~7.5Ω | 10kW~15kW | Mais comum, custo-benefício |
| High‑frequency | High‑inertia fan/centrifuge, fast decel ≤10s | 10%~20% | 6.5Oh (padrão) | 15kW~30kW | Enhanced cooling, parallel resistors |
| Contínuo | Potential load, long‑term lowering | ≥20% | 6.5Oh (mandatory) | ≥30kW (genuine 65kW preferred) | Independent thermal protection + forced cooling |
3.1 Genuine Complete Set
Unidade de Frenagem: FR-BU2-H75K
Resistor de Frenagem: MT-BR5-H75K (6.5Oh, 65kW)
3.2 Economic Compatible Types
Básico: RXLG 10kW 10Ω 1000V
Em geral: RXLG 15kW 7.5Ω 1000V
Pesado: RXLG 30kW 6.8Ω 1000V (or two 15kW 13.6Ω in parallel)
- Fiação, Instalação & Parâmetros
4.1 Safety Wiring Rules
Sequência: Inverter `P/+` → Braking Unit `P/+`; Inverter `N/-` → Braking Unit `N/-`; Braking Unit → Resistor.
Do NOT connect resistor directly to P/N.
Cable length ≤5m; max 10m for twisted pair.
Cable section ≥14mm², voltage rating ≥1000V.
Connect resistor thermal contact to inverter emergency stop.
4.2 Thermal Installation
Monte verticalmente, sufficient clearance, no enclosure blocking.
Keep ≥30cm from inverter and PLC.
For heavy duty: add forced cooling fan.
4.3 Key Inverter Parameters
| Parameter No. | Nome | Contexto | Descrição |
| Pr.30 | Regenerative brake selection | 1 | Enable external braking unit |
| Pr.70 | Special regenerative brake | 0 | For FR-BU2 series |
| Pr.8 / Pr.11 | Accel / Decel time | Set by load | Avoid overload and overvoltage trip |
| Pr.150 | Overvoltage stall level | 660V | Match braking unit voltage |
- Falhas & Soluções
| Sintoma | Main Checks |
| EOV overvoltage fault during deceleration | Loose resistor wire, faulty braking unit, excessive resistance, short decel time, incorrect parameters |
| Braking unit alarm / burnout | R < 6.5Oh, reversed wiring, resistor short, resfriamento deficiente |
| Resistor overheat / burnout | Under‑rated power, conexão solta, IGBT breakdown, insufficient cooling |
| Weak braking, long stopping time | Excessive resistance, parâmetros errados, braking unit disabled |
