Fuji Electric TEC-1VM EP-3955B Inverter Motherboard

Product Details

TEC-1VM EP-3955B Product Description

The Fuji Electric EP-3955B is a system-matched inverter motherboard engineered for seamless integration within the FRENIC series drive platform. Designed to serve as the central signal processing and control coordination layer inside FRENIC-series variable frequency drives, the EP-3955B governs the interaction between the power conversion stage, gate drive circuitry, feedback signal conditioning, and the upper-level control network. In modern industrial automation architectures, the inverter motherboard is not a peripheral component — it is the functional core that determines drive responsiveness, diagnostic transparency, and long-term system reliability.

Within a layered control architecture, the EP-3955B operates at the intersection of the control layer and the execution layer. It receives command signals from the PLC or DCS — such as a Fuji Electric MICREX-SX series controller or a third-party Modbus/PROFIBUS master — processes speed reference, torque limit, and direction commands, and translates these into precise PWM gate signals for the IGBT power module. Simultaneously, it manages real-time feedback from current sensors, encoder interfaces, and thermal monitoring circuits, feeding this data back to the control layer for closed-loop regulation and fault diagnostics. This bidirectional signal flow is what enables the FRENIC drive to maintain stable output across variable load conditions in demanding process environments.

The EP-3955B is built to support the full FRENIC system ecosystem. When deployed alongside the FRENIC-Multi or FRENIC-Ace drive chassis, it ensures that the drive's I/O expansion modules — including digital input cards, analog output cards, and relay output boards — operate with consistent signal timing and minimal latency. The motherboard's internal bus architecture is designed to accommodate optional communication cards such as the OPC-G1-PRT (PROFIBUS-DP) or OPC-G1-DEV (DeviceNet) option boards, enabling the drive to participate in plant-wide fieldbus networks without requiring external protocol converters or signal gateways.

From a system architecture perspective, the EP-3955B contributes directly to control architecture consistency. In multi-drive installations — such as those found in conveyor systems, pump stations, compressor banks, or winding lines — maintaining uniform motherboard specifications across all drive units simplifies commissioning, reduces spare parts inventory complexity, and ensures that firmware updates and parameter migration can be executed uniformly across the fleet. Engineers managing large-scale FRENIC deployments benefit from the EP-3955B's role as a standardized control core, which supports predictable behavior across varying load profiles and environmental conditions.

The EP-3955B also plays a critical role in redundancy and fault isolation design. In applications where drive availability is mission-critical — such as water treatment lift stations, petrochemical compressor drives, or steel mill rolling mill drives — the ability to replace the inverter motherboard as a discrete field-replaceable unit (FRU) without replacing the entire drive chassis significantly reduces mean time to repair (MTTR). Maintenance teams can stock the EP-3955B as a targeted spare, perform board-level swap procedures during planned maintenance windows, and restore full drive functionality without the lead times associated with complete drive procurement.

Signal integrity is another dimension where the EP-3955B delivers measurable value. The motherboard's analog input conditioning circuits are designed to minimize noise pickup from adjacent power wiring, which is a persistent challenge in control cabinet environments where drive output cables, 24 VDC control wiring, and fieldbus cables share common cable trays. By maintaining clean signal references at the motherboard level, the EP-3955B reduces the risk of nuisance trips caused by signal interference, contributing to higher system uptime and more reliable process control.

In terms of thermal management, the EP-3955B is designed to operate within the thermal envelope of the FRENIC drive chassis. Its component layout accounts for airflow patterns generated by the drive's internal cooling fan, ensuring that heat-sensitive components on the motherboard — including the DSP, gate driver ICs, and power supply regulators — remain within their rated operating temperature ranges even during sustained high-load operation. This thermal discipline is essential in enclosed control panel installations where ambient temperatures may approach the upper limits of the drive's rated operating range.

The EP-3955B is fully compatible with the FRENIC-series parameter backup and restoration workflow. Using the Fuji Electric keypad loader or the FRENIC Loader PC software, engineers can back up drive parameters to an external device, replace the EP-3955B motherboard, and restore the parameter set to the new board — minimizing configuration time during corrective maintenance. This workflow is particularly valuable in OEM machine builder environments where identical drive configurations must be replicated across multiple machine units or production lines.

For system integrators specifying components for new installations, the EP-3955B represents a proven, factory-tested control core with a documented compatibility matrix within the FRENIC platform. It is available from NANKMOS with pre-shipment functional testing, ensuring that each unit is verified for basic electrical integrity before dispatch. Combined with a 12-Month Warranty covering manufacturing defects and component failures under normal operating conditions, the EP-3955B offers a reliable procurement path for both OEM build programs and MRO replacement requirements.

The EP-3955B motherboard achieves its full performance potential when deployed as part of a coherent, multi-layer automation architecture. At the control layer, a Fuji Electric MICREX-SX series PLC or a compatible third-party DCS controller issues speed and torque commands to the FRENIC drive via a fieldbus network. The EP-3955B processes these commands and generates the corresponding PWM output to the drive's IGBT power module, which in turn drives the motor load.

At the I/O layer, FRENIC-series digital input expansion cards and analog output option boards connect to the EP-3955B's internal bus, extending the drive's signal interface to external sensors, actuators, and process instruments. In applications requiring precise process feedback — such as pressure-controlled pump systems or tension-controlled winding lines — analog input signals from 4–20 mA transmitters are conditioned by the EP-3955B's onboard analog input circuits before being used in the drive's PID control loop.

At the communication layer, option cards such as the OPC-G1-PRT PROFIBUS-DP adapter or the OPC-G1-DEV DeviceNet adapter plug directly into the EP-3955B's option slot, enabling the FRENIC drive to participate in plant-wide fieldbus networks. In Ethernet-based architectures, the OPC-G1-ETH EtherNet/IP option card provides integration with Rockwell Automation or Omron PLC platforms. Industrial Ethernet switches — such as managed switches supporting PROFINET or EtherNet/IP — connect the drive network to the plant backbone, with the EP-3955B serving as the drive-side protocol endpoint.

At the power layer, a dedicated 24 VDC control power supply — typically a DIN-rail mounted unit from the Fuji Electric or Phoenix Contact range — provides stable control voltage to the EP-3955B and associated I/O circuits, isolated from the drive's main power input. This isolation prevents control circuit disruption during main power fluctuations or soft-start sequences. At the HMI layer, the Fuji Electric TP series or GOT series operator panels connect to the FRENIC drive via RS-485 or Ethernet, providing operators with real-time drive status, fault history, and parameter adjustment capability — all coordinated through the EP-3955B's communication interface.

At the protection layer, motor thermistor inputs and external fault relay contacts connect to the EP-3955B's digital input terminals, enabling the drive to respond to motor overtemperature conditions or external interlock signals with configurable fault responses. In redundant drive architectures, a bypass contactor assembly — controlled by the EP-3955B's relay output — allows the motor to be switched to direct-on-line operation in the event of a drive fault, maintaining process continuity during corrective maintenance. Signal isolators, such as DIN-rail mounted 4–20 mA loop isolators, protect the EP-3955B's analog input circuits from ground loop interference in installations with long cable runs between the drive cabinet and field instruments.

Manufacturing & Packaging Lines: In automated packaging and assembly lines, the EP-3955B-equipped FRENIC drive controls conveyor motors, indexing drives, and tension control systems. The motherboard's fast PWM response and closed-loop feedback capability support precise speed synchronization across multi-axis conveyor systems, reducing product misalignment and improving throughput consistency.

Water & Wastewater Treatment: Pump station and blower applications in water treatment facilities rely on FRENIC drives with EP-3955B motherboards for reliable variable-speed pump control. The drive's PID control loop — managed by the EP-3955B — maintains constant system pressure or flow rate in response to varying demand, reducing energy consumption and extending pump mechanical life.

Petrochemical & Process Industries: In compressor and agitator drive applications within petrochemical plants, the EP-3955B's robust signal conditioning and fault diagnostic capability support continuous process operation. The motherboard's compatibility with PROFIBUS-DP and DeviceNet option cards enables integration with DCS platforms commonly used in process industry automation, including Yokogawa CENTUM and Honeywell Experion systems.

Mining & Metallurgy: Conveyor drives, crusher drives, and rolling mill applications in mining and metallurgical facilities demand high drive reliability and rapid fault recovery. The EP-3955B's field-replaceable design supports planned maintenance strategies in these high-availability environments, where unplanned drive downtime directly impacts production output and revenue.

Marine & Offshore: In marine propulsion auxiliary systems and offshore platform utilities, FRENIC drives equipped with EP-3955B motherboards provide reliable variable-speed control for pumps, fans, and winch drives in environmentally demanding conditions. The motherboard's thermal design supports operation within the drive's rated ambient temperature range, which is critical in enclosed machinery spaces with limited ventilation.

Q1: Is the EP-3955B compatible with all FRENIC series drive models, and how do I confirm compatibility before ordering? The EP-3955B is designed for specific FRENIC series drive models, including variants within the FRENIC-Multi and FRENIC-Ace product families. Compatibility is determined by the drive's model number, power rating, and firmware version. Before ordering, provide your complete drive model number to NANKMOS — our technical team will confirm EP-3955B compatibility against the Fuji Electric FRENIC spare parts matrix and advise on any firmware considerations for the replacement board.

Q2: What is the recommended installation and commissioning procedure when replacing the EP-3955B motherboard in a live production environment? The recommended procedure involves backing up all drive parameters using the Fuji Electric keypad loader or FRENIC Loader PC software before removing the existing motherboard. After installing the EP-3955B, restore the parameter backup to the new board and perform a no-load test run to verify correct operation before reconnecting the motor load. NANKMOS recommends scheduling motherboard replacement during a planned maintenance window and having a qualified drive technician perform the installation. Our technical support team can provide model-specific installation guidance upon request.

Q3: What does the 12-Month Warranty cover, and what is the process for warranty claims on the EP-3955B? The 12-Month Warranty covers manufacturing defects and component failures occurring under normal operating conditions within 12 months of the shipment date. It does not cover damage resulting from incorrect installation, overvoltage events, environmental contamination, or unauthorized modification. To initiate a warranty claim, contact NANKMOS at [email protected] with your order reference, a description of the fault symptom, and any available fault code data from the drive. Our team will assess the claim and arrange for replacement or repair as appropriate.