Mitsubishi FR-F740-S75K-CHT Inverter

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.

Model Explanation

コード	説明
フランス	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

アイテム	仕様
Applicable motor capacity	75kW (three-phase induction motor)
Rated output capacity	110kVA for both SLD / LD duty
Rated output current	144あ (common for SLD light duty / LD heavy duty)
Overload capacity	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, frequency: ±5%
Output frequency range	0.2~400Hz, speed control range 1:100 (under vector control)
Protection structure	Open type IP00, must be installed in a qualified enclosure
Cooling method	Forced air cooling
約. weight	35kg
Dedicated DC reactor	FR-HEL-H75K

コア機能 & 特徴
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.

高い信頼性 & Full Protection

包括的な保護: 過電流, 過電圧, 不足電圧, overheat, 過負荷, stall prevention, 地絡. Adaptive to power fluctuations. Designed lifetime of main capacitors and fans exceeds 10 年.

Rich Communication & 拡大

Standard RS485, Modbus-RTU. Optional CC-Link, 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.

Main Applications

Primary: 75kW 3-phase 380V fans, パンプス, compressors — industrial water supply/drainage, central AC water circulation, boiler ID/FD fans, HVAC, water treatment aeration/booster systems.

Secondary: Conveyors, mixers, ventilation equipment. Ideal for continuous operation requiring high efficiency, stability, and long service life.

インストール & Commissioning Guidelines
インストール: IP00 open type must be installed in a proper enclosure, vertically mounted with sufficient cooling space. Ambient temp: -10~+50°C. Avoid moisture, dust, corrosive gas, strong EMI.
Wiring: 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.
Control Modes: PU (keypad), external terminal, コミュニケーション. Perform motor auto-tuning first. Set acceleration/deceleration time, PID, and protection levels accordingly.
接地: Reliable independent grounding, resistance ≤10Ω. Do not share ground with high-power equipment.
Typical Faults & トラブルシューティング

故障コード	説明	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	Motor overload	Check motor stall, 過負荷, or mismatched motor rated parameters

Complete Guide to Braking Resistor Selection for Mitsubishi FR-F740-S75K-CHT

Critical Pre-Selection Notes (必読)

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. Otherwise, permanent damage to the inverter main circuit will occur.

1.1 Typical Applications Requiring Braking Resistors

Fast motor deceleration / 停止, much shorter than free-run time

High-inertia loads (大型ファン, パンプス, 遠心分離機)

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:

アイテム	Genuine Model	主要なパラメータ
Braking unit	FR-BU2-H75K	For 75kW 400V-class inverter, max withstand voltage 800V DC, IP00, forced air cooling
Minimum allowable external resistance	6.5Ω	Never use resistance lower than this value, otherwise IGBT will burn out
Genuine matching resistor unit	MT-BR5-H75K	Standard resistance 6.5Ω, suitable for 10% ED duty, built‑in overheat protection

Braking Resistor Selection Rules

Core parameters: 抵抗, rated power, voltage class.

2.1 Resistance (R)

Must be ≥ 6.5Ω

Practical range: 6.5Ω ~ 20Ω

2.2 Rated Power (P)

Braking resistors are intermittent duty. Selection depends on ED% (duty ratio).

Genuine MT-BR5-H75K: 65kW, suitable for ED ≤10%.

2.3 Withstand Voltage & タイプ

Voltage class: ≥ 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, thermal protection
Duty-Based Selection Table

Duty Level	Typical Application	ED%	Recommended R	Recommended P	注意事項
Light basic	Occasional stop, decel ≥30s, ≤10 starts per shift	≤5%	6.8Ω~10Ω	7.5kW~10kW	Basic overvoltage protection only
General	Normal fan/pump, frequent starts, decel 10~30s	5%~10%	6.5Ω~7.5Ω	10kW～15kW	Most common, cost‑effective
High‑frequency	High‑inertia fan/centrifuge, fast decel ≤10s	10%~20%	6.5Ω (標準)	15kW～30kW	Enhanced cooling, parallel resistors
Continuous	Potential load, long‑term lowering	≥20%	6.5Ω (mandatory)	≥30kW (genuine 65kW preferred)	Independent thermal protection + forced cooling

3.1 Genuine Complete Set

Braking Unit: FR-BU2-H75K

制動抵抗器: MT-BR5-H75K (6.5Ω, 65kW)

3.2 Economic Compatible Types

基本: RXLG 10kW 10Ω 1000V

General: RXLG 15kW 7.5Ω 1000V

Heavy: RXLG 30kW 6.8Ω 1000V (or two 15kW 13.6Ω in parallel)

Wiring, インストール & パラメータ

4.1 Safety Wiring Rules

Sequence: 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

垂直に取り付ける, 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.	名前	Setting	説明
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

Faults & ソリューション

症状	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 < 6.5Ω, reversed wiring, resistor short, poor cooling
Resistor overheat / burnout	Under‑rated power, 接続が緩い, IGBT breakdown, insufficient cooling
Weak braking, long stopping time	Excessive resistance, wrong parameters, braking unit disabled