HITACHI SJ300 Modules — SJ300TM 3B295619-3 Inverter Terminal Board

Technical Dossier

Product Details And Specifications

HITACHI SJ300 Series: Comprehensive Module Range and Technical Overview

The HITACHI SJ300 series is a general-purpose variable frequency drive (VFD) platform deployed extensively across global heavy industry, including petrochemical plants, nuclear auxiliary systems, offshore refineries, and large-scale HVAC infrastructure. Manufactured in Japan, the SJ300 line covers output ranges from 0.4 kW to 400 kW (three-phase 200V and 400V class), making it one of the most widely installed mid-range inverter families in Asia-Pacific and EMEA industrial facilities. Its modular internal architecture — separating the control board, terminal board, gate driver board, power board, and operator panel — means that component-level repair and board replacement remain the primary maintenance strategy for installed base units, particularly in facilities where full drive replacement would require costly re-commissioning.

The Evolution of SJ300 Architecture

The SJ300 platform was introduced by Hitachi Industrial Equipment Systems in the early 2000s as a successor to the L300P and SJ200 series, incorporating enhanced V/f control, sensorless vector control, and expanded communication option slots. The internal PCB architecture evolved through several hardware revisions identifiable by suffix codes on the board label (e.g., 3B295619-1, -2, -3), with each revision addressing EMC compliance updates, IGBT gate drive timing refinements, and thermistor circuit modifications. The SJ300 was officially succeeded by the WJ200 and SJ700 series for new installations, but the SJ300 remains in active service across thousands of legacy installations. Compatibility between hardware revisions is generally maintained within the same frame size, but cross-frame substitution requires verification of connector pinout and firmware version. The SJ300TM terminal board (3B295619-3) is the third hardware revision of the main control terminal interface PCB, responsible for routing analog input/output signals, digital I/O, RS485 communication, and option card interface signals between the operator and the main inverter control board.

SJ300 Full Catalog & Functionalities (SKU List)

The following SKUs represent verified components and drive models within the HITACHI SJ300 platform. Each entry reflects a distinct functional role within the drive system.

SJ300TM 3B295619-3: Main inverter terminal board, Rev.3; routes analog/digital I/O and RS485 signals.
SJ300-004LFU: 0.4 kW / 200V class SJ300 inverter, single-phase input, IP20 enclosure.
SJ300-007LFU: 0.75 kW / 200V class inverter, standard V/f and sensorless vector control.
SJ300-015LFU: 1.5 kW / 200V class inverter, built-in EMC filter, DIN rail mountable.
SJ300-022LFU: 2.2 kW / 200V class inverter, supports PID feedback control loop.
SJ300-040LFU: 4.0 kW / 200V class inverter, enhanced braking transistor circuit.
SJ300-075LFU: 7.5 kW / 200V class inverter, expanded I/O terminal block configuration.
SJ300-150LFU: 15 kW / 200V class inverter, dual cooling fan assembly, frame D housing.
SJ300-004HFU: 0.4 kW / 400V class inverter, three-phase input, compact frame A.
SJ300-022HFU: 2.2 kW / 400V class inverter, supports DeviceNet option card slot.
SJ300-055HFU: 5.5 kW / 400V class inverter, integrated DC bus choke terminals.
SJ300-110HFU: 11 kW / 400V class inverter, frame C, supports encoder feedback option.
SJ300-220HFU: 22 kW / 400V class inverter, dual IGBT module configuration, frame D.
SJ300-370HFU: 37 kW / 400V class inverter, forced-air cooling, frame E housing.
SJ300-750HFU: 75 kW / 400V class inverter, large frame, parallel IGBT stack.
SJ300-1500HFU: 150 kW / 400V class inverter, cabinet-mount configuration, dual rectifier bridge.
3B295619-1: Terminal board Rev.1, early production variant; limited RS485 shielding.
3B295619-2: Terminal board Rev.2; updated analog input filter capacitors.
SJ-DV: DeviceNet communication option card for SJ300 option slot.
SJ-PB: PROFIBUS-DP communication option card, compatible with SJ300 frame B–E.

Sourcing Hard-to-Find & Obsolete SJ300 Parts

The SJ300 series entered end-of-life status for new production, with Hitachi Industrial Equipment Systems transitioning the installed base to the WJ200 and SJ700 platforms. However, the volume of SJ300 units in active service across chemical processing, water treatment, and power generation facilities means that demand for spare boards — particularly the terminal board assembly (3B295619-x series) and gate driver PCBs — remains consistent. DriveKNMS maintains a dedicated inventory of SJ300 spare boards sourced from decommissioned units, authorized distributor overstock, and verified third-party refurbishment channels. All boards are catalogued by hardware revision suffix to ensure cross-compatibility verification prior to dispatch. For facilities operating under long-term service agreements where drive replacement is not feasible within the maintenance window, DriveKNMS provides board-level exchange programs with lead times typically under 5 business days for stocked items.

Quality Control for the SJ300 Range

The SJ300 terminal board (3B295619-3) and associated control PCBs undergo a structured inspection and functional test protocol before dispatch. Each board is visually inspected under magnification for solder joint integrity, capacitor ESR degradation, and trace corrosion — failure modes common in boards recovered from high-humidity or chemically aggressive environments. Functional testing is performed using a dedicated SJ300 drive test rig that applies actual bus voltage and simulates analog input signals, digital command sequences, and RS485 communication handshakes to verify full terminal functionality. Gate driver boards are tested under load using a resistive dummy motor load to confirm IGBT switching waveforms are within Hitachi factory specification. All tested units are issued a test report documenting pass criteria and are shipped with ESD-protective packaging and desiccant.