The MR-J4-500B is Mitsubishi Electric’s 5 kW MELSERVO-J4 series servo amplifier for 200 V single-phase or three-phase AC power supply with SSCNET III/H optical fibre network interface — providing closed-loop servo control at continuous rated output current of 23.0 A for Mitsubishi HG-SR and HG-RR series 5 kW servo motors in demanding multi-axis SSCNET III/H applications including large CNC machining centre feed axes, heavy gantry systems, and large-format automated manufacturing equipment where 5 kW of continuous servo power is required within a coordinated SSCNET III/H motion control architecture. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the MR-J4-500B?
The MR-J4-500B is a MELSERVO-J4 series servo amplifier providing 5 kW (5,000 W) continuous output power via SSCNET III/H optical fibre — the SSCNET III/H network-commanded counterpart to the MR-J4-500A pulse train input amplifier, sharing the identical 5 kW power stage but receiving all position and speed commands exclusively via SSCNET III/H at 0.888 ms or 0.444 ms communication cycle time. The MR-J4-500B is compatible with Mitsubishi HG-SR502, HG-SR5024, HG-RR503, and equivalent 5 kW servo motors with 22-bit multi-turn absolute encoders. The amplifier’s housing width increases to 130 mm compared to the MR-J4-350B’s 85 mm, reflecting the significantly larger power components, heat sink, and cooling fan required for 5 kW output at 23 A continuous current — this width increase represents the transition from the compact small-to-medium frame amplifiers to the large-frame high-power amplifiers in the MR-J4-B series. The MR-J4-500B includes all MR-J4 premium features: Advanced Vibration Suppression Control II with automated machine resonance detection, fully closed-loop dual encoder support, STO safety function compliant with IEC 61800-5-2 SIL2 and EN ISO 13849-1 PLe, and MR Configurator2 USB commissioning interface.
Key Technical Specifications
- Model: MR-J4-500B
- Rated Output Power: 5 kW (5,000 W)
- Power Supply: 200–240 VAC single-phase or three-phase, 50/60 Hz
- Continuous Output Current: 23.0 A
- Maximum Output Current: 69.0 A (3× continuous peak)
- Compatible Servo Motors: HG-SR502, HG-SR5024, HG-RR503, HG-RR5034 and equivalent
- Command Interface: SSCNET III/H optical fibre (150 Mbps full-duplex)
- Communication Cycle: 0.444 ms or 0.888 ms (selectable)
- Encoder Interface: Serial 22-bit absolute encoder (262,144 pulses/rev)
- Safety Function: STO (Safe Torque Off), IEC 61800-5-2 SIL2 / EN ISO 13849-1 PLe
- Regenerative Brake: Built-in, external MR-RB series resistor connectable
- Housing Width: 130 mm
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 130 mm × 250 mm × 182 mm
- Weight: Approx. 3.5 kg
Typical Industrial Applications
The MR-J4-500B is the most commonly specified high-power amplifier in SSCNET III/H multi-axis machine tool systems, where 5 kW continuous servo power covers the majority of large CNC machining centre feed axis requirements. In 5-axis horizontal machining centres, the MR-J4-500B drives the X, Y, and Z linear feed axes where the combined saddle mass, cutting force reaction, and required rapid traverse acceleration demand 5 kW of sustained servo power — the SSCNET III/H communication enables tighter inter-axis synchronisation for simultaneous 5-axis machining than pulse train systems can achieve. In large-format laser and plasma cutting machines with gantry structures up to 4 m in width, the MR-J4-500B drives the transverse (Y) axis where the beam gantry mass at high traverse speeds requires 5 kW continuous power. Semiconductor wafer inspection systems and flat panel display manufacturing equipment use the MR-J4-500B for high-precision long-stroke linear axes where the 5 kW power combined with the 22-bit absolute encoder’s nanometre-level position resolution enables high-speed, high-accuracy scanning at the throughput rates required for volume production. In large-format automated fibre placement (AFP) machines for composite aerospace component manufacturing, the MR-J4-500B drives the fibre placement head traverse axis where the combined head mass and fibre tension reaction force requires sustained 5 kW servo capability at the programmed layup speeds.
Replacement & Upgrade Notes
The MR-J4-500B is the direct SSCNET III/H successor to the MR-J3-500B in the 5 kW 200 V SSCNET class, providing all the MR-J4 generation improvements over the MR-J3: 22-bit encoder resolution versus 17-bit, AVSC II versus AVSC I, built-in STO versus external safety relay requirement, and 0.444 ms minimum communication cycle versus 0.888 ms. For systems currently using MR-J3-500B amplifiers on a SSCNET III chain, migration to MR-J4-500B requires upgrading the motion controller to SSCNET III/H capability simultaneously (Q172DSCPU, Q173DSCPU, or RD77MS) — MR-J3 and MR-J4 amplifiers cannot share the same SSCNET chain. The 5 kW HG-SR502 and HG-SR5024 motors from the MR-J3 era can continue operating with the MR-J4-500B in motor compatibility mode — retaining the motor while upgrading the amplifier provides a cost-effective migration path where the motor replacement can be deferred to a subsequent maintenance cycle. When replacing MR-J3-500B amplifiers with MR-J4-500B in a planned system upgrade, use MR Configurator2’s MR-J3 parameter conversion function to create an initial MR-J4 parameter set from the existing MR-J3 parameter file, then re-run auto-tuning with the converted parameters as a starting point — this approach significantly reduces commissioning time compared to tuning from factory defaults.
Frequently Asked Questions
Q: Can the MR-J4-500B and MR-J4-500A be used together in the same machine — one SSCNET, one pulse train — for different axes?
A: Yes, but not on the same SSCNET III/H chain. The MR-J4-500B (SSCNET III/H) connects to the motion controller via the SSCNET chain, while the MR-J4-500A (pulse train) connects to a separate positioning module (such as QD75MH4) via individual pulse cables. Both amplifiers can exist in the same machine panel and be programmed from the same MELSEC-Q or iQ-R controller — the SSCNET axes are managed by the motion CPU and the pulse train axes by the positioning module, with the controller coordinating both axis types in the machine program.
Q: What is the maximum number of MR-J4-500B amplifiers that can share a single three-phase 200 VAC 30 A supply circuit?
A: At 5 kW output with 200 VAC three-phase supply, the MR-J4-500B draws approximately 16 A per phase at full load. A 30 A three-phase circuit can therefore theoretically supply one MR-J4-500B at full load with adequate margin. For two MR-J4-500B amplifiers, a 40 A or larger three-phase circuit is required. In practice, not all axes reach full load simultaneously — in a 3-axis machining centre, the concurrent power demand during cutting is typically 50–70% of the sum of individual axis ratings, allowing a moderately sized supply to serve multiple amplifiers.
Q: Does the MR-J4-500B support the Mitsubishi iQ-R motion module (RD77MS) as well as the Q-series motion CPU?
A: Yes. The MR-J4-500B is compatible with all SSCNET III/H motion controllers including the MELSEC iQ-R RD77MS (up to 16 axes), MELSEC-Q Q172DSCPU (up to 32 axes), Q173DSCPU (up to 96 axes), and the FX3U-20SSC-H (up to 2 axes). The SSCNET III/H communication protocol is identical regardless of which controller is used, and the MR-J4-500B’s servo parameters, auto-tuning, and MR Configurator2 interface operate identically with all compatible controllers.
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