Mitsubishi FR-A840-00126 Drive Replacement

Overview

The Mitsubishi Electric FR-A840-00126 (also designated as FR-A840-5.5K-GF in regional markets) is a high-performance variable frequency drive (VFD) from the workhorse FR-A800 series. Rated for a 5.5kW (7.5 HP) motor capacity under Normal Duty (ND) conditions, it is widely utilized across heavy industries in applications demanding precise vector control, high starting torque, and integrated PLC positioning functionality—such as gantry cranes, winders, rotary kilns, and high-capacity extruder lines.

When an FR-A840-00126 fails or requires modernization, system integrators and maintenance managers must plan the replacement process carefully. This technical guide outlines the precise specifications of the legacy hardware, evaluates direct replacement options, highlights critical installation considerations, and provides a comprehensive migration guide to minimize operational downtime.

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Legacy Product Information

The FR-A840-00126 sits within Mitsubishi Electric's premium FR-A800 family of inverters. Its modular control system, Real Sensorless Vector Control (RSVC), and closed-loop vector capabilities make it highly versatile. It uses a structured part number system where "00126" refers to the rated output current of 12.6 Amperes (under Light Duty conditions).

Technical Specifications

• Manufacturer: Mitsubishi Electric
• Series: FR-A800 (specifically standard 400V three-phase input models)
• Full Order Number: FR-A840-00126-2-60 (often abbreviated as FR-A840-00126)
• Nominal Motor Power: 5.5 kW (7.5 HP)
• Input Ratings: 3-phase, 380 to 480 V AC (+10% / -15%), 50/60 Hz
• Output Ratings: 3-phase, 380 to 480 V AC (dependent on input voltage)
• Overload Current Capacities (Duty Cycles):
  • SLD (Super Light Duty): 16.0 A (at 40°C), 110% overload for 60s
  • LD (Light Duty): 12.6 A (at 50°C), 120% overload for 60s
  • ND (Normal Duty): 12.0 A (at 50°C), 150% overload for 60s
  • HD (Heavy Duty): 9.0 A (at 50°C), 200% overload for 60s
• Enclosure Rating: IP20 / Open Type
• Dimensions: 150 mm (Width) x 260 mm (Height) x 170 mm (Depth) [Frame Size C1]
• Weight: 3.5 kg (approx. 7.7 lbs)
• Lifecycle Status: Active, but highly requested for hot-swaps, panel migrations, or Ethernet-enabled upgrades.

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Recommended Replacements

If you are replacing a faulty FR-A840-00126-2-60, you have three primary paths. Table 1 outlines these replacement options based on system requirements and physical constraints.

Table 1: Replacement Comparison Matrix

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Compatibility Considerations

Before executing a drive replacement, evaluate three core system integrations:

1. Control Logic and Spring Terminal Blocks

Standard FR-A800 series drives utilize spring-clamp (tension clamp) control terminal blocks, unlike early generations (such as the legacy FR-A740) which used screw terminals. Ensure control wires are terminated with appropriate bootlace ferrules (cross-section 0.3 to 1.25 mm²). Verify the Sink/Source Logic Jumper (located behind the terminal cover) matches your PLC's control strategy (SINK, SOURCE, or EXT) before applying power.

2. Network Options and Interface Cards

If your matching FR-A840-00126 uses option cards inserted into Slots 1, 2, or 3 (such as the FR-A8NC for CC-Link or FR-A8ND for DeviceNet), these cards must be physically uninstalled from the legacy drive and seated correctly in the replacement unit. Ensure the optional slot ground cables are reconnected to the drive frame.

3. Brake Resistor & Dynamic Braking (DB) Unit

The FR-A840-00126 has a built-in brake transistor. If your process utilizes dynamic braking via terminal PR and PX, verify that the jumper between PR and PX is removed if an external resistor with active thermal overload protection is integrated.

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Upgrade Benefits

Upgrading to the modern Ethernet-equipped variant (FR-A840-00126-E2-60) or integrating newer firmware revisions offers immediate field operational enhancements:

• Integrated Multi-Network Support: No longer requires network option cards. Dual RJ45 ports permit ring or daisy-chain topologies on CC-Link IE Field Basic, Modbus/TCP, EtherNet/IP, BACnet/IP, and PROFINET.
• Embedded PLC Programming: The A800 series comes with mini-PLC programming tools (via Mitsubishi’s Developer / Works software), allowing local control sequence execution directly on the drive, relieving load on the main controller.
• Predictive Diagnostics: Monitors the cooling fans and internal capacitors, generating pre-failure warnings on the parameter unit (FR-PU08) to improve preventative maintenance metrics.

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Common Migration Challenges

When swapping an FR-A840-00126, commissioning engineers often encounter specific bottlenecks:

• Parameter Lockout (Pr. 77): When writing new parameters, the drive must be in "PU Mode" or "Network Mode" with the motor stopped. Read or write errors will halt progress if Pr. 77 (Parameter Write Selection) is incorrectly configured.
• IP Address Conflicts on Ethernet Variants (E2): If migrating to the -E2 model, the default IP address assignment config might trigger network collisions. You must assign unique static IPs using the FR Configurator2 software or the digital dial on the FR-DU08 panel.
• Autotuning Discrepancies: If vector control is utilized, transferring old tuning parameters to a new drive can result in motor instability. A fresh round of Offline Auto-Tuning is highly recommended if you are replacing the core drive power block.

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Step-by-Step Replacement Procedure

Follow these detailed steps to safely replace your FR-A840-00126.

                  TYPICAL WIRING SCHEMATIC
                  
                        3-Phase AC
                     (380-480V 50/60Hz)
                      L1    L2    L3
                      |     |     |
                     [MC]  [MC]  [MC]  (Magnetic Contactor)
                      |     |     |
                      v     v     v
                  +-------------------+
                  |  R/L1  S/L2  T/L3 | <-- Power Input
                  |                   |
                  |                   |
                  |    FR-A840-00126  |
                  |                   |
                  |   U     V     W   | <-- Motor Output
                  +---|-----|-----|---+
                      |     |     |
                      v     v     v
                     (M)   (M)   (M)  (3-Phase AC Motor)

Phase 1: Isolation and De-energization

1. Isolate Input Power: Turn off the main MCCB (Molded Case Circuit Breaker) powering the branch circuit. Follow 1910.147 OSHA Lockout/Tagout (LOTO) procedures.
2. Wait for DC Bus Discharge: The drive's internal capacitors store energy. Wait a minimum of 10 minutes after power-down.
3. Confirm Safe Voltage levels: Measure the voltage between the DC positive terminal (P/+) and negative terminal (N/-) with a properly rated digital multimeter (DMM) set to DC voltage. Confirm it reads under 20V DC before touching any internal bus bars or terminals.

Phase 2: Configuration Salvage & Hardware Removal

1. Save Parameters: If the damaged drive is still communicating, hook up a laptop containing FR Configurator2 using a standard USB-A to USB-Mini-B cable. Execute a full parameter read and save the .mcf files. Alternatively, use the FR-DU08 or FR-PU08 operation keypad to copy parameters into the non-volatile memory of the keypad.
2. Disconnect Wires: Label every control terminal cable. Disconnect the main supply terminals (R/L1, S/L2, T/L3), motor cables (U, V, W), dynamic braking terminals (P/+, PR), and the grounding terminal.
3. Physical Extraction: Loosen the four mounting screws on the top and bottom corners of the drive frame. Keep these screws for the replacement. Slide the unit up and off the panel backplate.

Phase 3: Replacement Drive Commissioning

1. Mount the Replacement: Position the new FR-A840-00126 drive over the alignment slots and secure the four mounting bolts to a torque spec of 2.5 N·m (22 in-lb).
2. Wire Connection: Connect the protective earth (PE) ground terminal first. Reinstall the power input and output lines. Hand-torque the main power terminals in a criss-cross pattern to 1.5 N·m (13 in-lb) to ensure optimal electrical contact without stripping the threads.
3. Re-engage Control Connectors: If you used separate control jumpers, configure your Sink/Source jumper pin. Insert the pre-wired terminal block assembly or terminate individual control signal wires according to the original labels.
4. Confirm Dynamic Brake connections: Ensure the correct configuration of brake resistor thermal links is active.

Phase 4: Parameter Upload and Testing

1. Initial Energization: Switch on the main supply breaker. Confirm the drive boots smoothly and showing the 0.00 Hz frequency command on the digital display without immediate fault alerts (such as E.OC1 or E.THT).
2. Write Saved Configurations: Use FR Configurator2 to write the saved .mcf parameter stack to the new unit. If copying via keypads (such as the FR-PU08), access parameter Pr.CP and execute "Parameter Copy Write".
3. Execute Motor Autotuning: If operating in Sensorless Vector Control mode, disconnect physical motor loads if possible. Set Parameter Pr. 9 (Motor rated current) to match your motor's nameplate, set Pr. 96 (Auto-tuning setting) to 1 (Tuning without rotation) or 101 (Tuning with rotation), and initiate a run command to perform parameter tuning.
4. Validate Rotation Direction: Perform a jog test at a low frequency (e.g., 5 Hz) using local panel PU control to check the physical rotation direction of the motor.

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Frequently Asked Questions

Q1: Can I replace my older legacy FR-A740-5.5K drive with the FR-A840-00126 directly?

Yes. The FR-A840-00126 is the direct spiritual generation-successor to the FR-A740-5.5K. While the mounting dimensions and screw holes are identical, the electrical terminal layout for control signals has transitioned from screws to push-in spring terminals, which requires re-terminating control wires with ferrules.

Q2: What does the "00126" in the part number actually stand for?

The digits indicate the rated output current under Light Duty (LD) rating conditions, which is exactly 12.6 Amperes. Under Normal Duty (ND) conditions, it outputs 12.0 Amperes, which aligns with standard 5.5kW AC induction motors.

Q3: My replacement drive displays error E.UVT immediately after powering on. What is wrong?

E.UVT indicates an Undervoltage Fault. Check your three-phase power supply on R/L1, S/L2, T/L3 to ensure it is consistently between 380V and 480V AC. Also verify that the jumpers connecting terminals P/+ and P1 are securely tightened.

Q4: Do I need a software license to copy parameters between drives?

No. While FR Configurator2 is highly useful for managing complete fleets, basic parameter transfers can be conducted entirely using the built-in FR-DU08 keypad or diagnostic FR-PU08 handheld programmer by utilizing the onboard "Parameter Copy" storage blocks.

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Related Products & Families

When carrying out replacements or panel retrofits, you may require matching auxiliary equipment. The following accessories are typically paired with the FR-A840-00126 drive:

• Operation Panels:
  • FR-DU08: Standard operational keypad unit.
  • FR-PU08: Deluxe parameter unit with interactive troubleshooting guides and 10-key numeric entry.
• Dynamic Braking Units and Resistors:
  • FR-ABR-H5.5K: Heavy-duty external braking resistor designed for high-inertia deceleration profiles.
• Input and Output Reactors:
  • FR-BAL-H5.5K: AC input harmonic suppression reactor.
  • FR-HAL-H5.5K: DC link reactor for harmonic mitigation.

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Need Help?

Whether you require a brand-new factory-sealed replacement unit, an emergency refurbished backup, or hard-to-find internal drive components, we have you covered.

Palm Parts Solution specializes in industrial automation parts supply, stocking both current-line and obsolete legacy VFDs. We provide high-quality new, refurbished, and surplus equipment backed by full warranties. Contact our team of applications engineers today for price quotes, real-time stock availability, and deep technical assistance for your Mitsubishi FR-A800 system lifecycle requirements.