Fuji Electric FRN3.7C1S-2J FRENIC-Mini Compact VFD

The Fuji FRN3.7C1S-2J is a FRENIC-Mini series variable frequency drive (VFD) designed for small industrial machinery. This model accepts single‑phase 200–240 V AC input and delivers three‑phase output up to 3.7 kW (5 HP). The drive features sensorless vector control, providing high starting torque and stable speed regulation. With a compact footprint (book style) and built‑in EMC filter, the FRN3.7C1S-2J is ideal for space‑constrained panels and applications such as fans, pumps, conveyors, and packaging equipment.

Technical Specifications

Functional Description

The FRN3.7C1S-2J converts single‑phase AC input to a variable‑frequency, variable‑voltage three‑phase output using IGBT technology. The sensorless vector control algorithm estimates rotor flux without an encoder, delivering 150% starting torque at 0.5 Hz. The drive includes an automatic torque boost function to compensate for voltage drop at low frequencies. A built‑in PID controller allows the VFD to regulate pressure, flow, or temperature directly, using an external analog sensor. The drive’s LCD keypad (optional, not included) provides English or local language menus for parameter setting and monitoring.

I/O and Control Terminals

The VFD has a terminal block with:

• 4 digital inputs (selectable functions: run/stop, forward/reverse, multi‑speed, etc.)

• 1 analog input (0–10V or 4–20mA) for speed reference

• 1 analog output (0–10V for frequency or current monitoring)

• 1 relay output (fault signal) and 1 open‑collector output (run status)

The RS‑485 port supports Modbus RTU, allowing connection to PLCs and HMIs. The drive also supports a keypad extension cable for remote mounting.

Protection and Safety

The FRN3.7C1S-2J incorporates comprehensive protection: electronic thermal overload (I²t) for motor, overcurrent stall prevention, overvoltage stall, undervoltage alarm, and ground fault detection. The built‑in dynamic braking chopper allows connection of an external braking resistor (optional) for rapid deceleration of high‑inertia loads. The drive also has an input phase loss detection.

Applications

Typical uses include small conveyors (belt and roller), centrifugal fans and blowers, circulation pumps, packaging machinery (sealers, wrappers), woodworking equipment, and laboratory mixers. The single‑phase input is convenient for facilities with limited three‑phase power.

Installation Guidelines

Mount the drive vertically on a flat, non‑combustible surface. Maintain 100 mm clearance above and below for cooling airflow. Connect the single‑phase supply to L1/L (R) and L2/N (S) terminals. Connect the motor to U/T1, V/T2, W/T3. Use shielded motor cables, and keep control wiring separate from power wiring. Set the rated motor current and basic parameters via the keypad or PC software.

Conclusion

The Fuji FRN3.7C1S-2J FRENIC-Mini VFD delivers high‑performance motor control in a compact, single‑phase‑input package, ideal for OEMs and retrofit applications requiring reliable speed control.