The MR-J3-200B is Mitsubishi Electric’s 2 kW MELSERVO-J3 series servo amplifier for 200 V single-phase or three-phase AC power supply with SSCNET III optical fibre network interface — a legacy product from Mitsubishi’s third-generation MELSERVO platform, providing 2 kW continuous servo control for HC-SFS202 and HC-RFS203 series servo motors in active multi-axis SSCNET III servo systems. Atlantech Drives holds stock of the MR-J3-200B. Contact us for fast worldwide delivery and competitive pricing.
What Is the MR-J3-200B?
The MR-J3-200B is a MELSERVO-J3 series servo amplifier providing 2 kW (2,000 W) continuous output power via SSCNET III optical fibre, compatible with Mitsubishi HC-SFS202, HC-RFS203, and equivalent 2 kW servo motors equipped with the MR-J3’s 17-bit multi-turn absolute encoder. As a SSCNET III amplifier, the MR-J3-200B receives all position commands from a Q172DSCPU or Q173DSCPU MELSEC-Q motion controller at 0.888 ms communication cycle time — no pulse train input is present. The MR-J3-200B shares the SSCNET III communication specification with all other MR-J3-B variants, with the 2 kW power stage providing the higher continuous torque capability required for heavier axis loads, longer ball screw axes, or higher-speed duty cycles compared to the 1 kW MR-J3-100B. The housing width increases to 70 mm for the 2 kW model compared to 55 mm for the 1 kW, reflecting the larger power components required at this output level. Like all MR-J3-B amplifiers, the MR-J3-200B does not include a built-in STO function — safety compliance requires external safety contactors, representing a significant difference from the current-generation MR-J4-200B which includes dual-channel STO compliant with IEC 61800-5-2 SIL2.
Key Technical Specifications
- Model: MR-J3-200B
- Rated Output Power: 2 kW (2,000 W)
- Power Supply: 200–240 VAC single-phase or three-phase, 50/60 Hz
- Continuous Output Current: 11.0 A
- Maximum Output Current: 33.0 A (3× continuous peak)
- Compatible Servo Motors: HC-SFS202, HC-RFS203, HG-SR202 (J4 motor, J3 compat. mode)
- Command Interface: SSCNET III optical fibre (10 Mbps)
- Communication Cycle: 0.888 ms
- Encoder Interface: Serial 17-bit absolute encoder (131,072 pulses/rev)
- Safety Function: None built-in (external safety contactor required)
- Regenerative Brake: Built-in, external MR-RB series resistor connectable
- Communication: USB (MR Configurator2)
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 70 mm × 170 mm × 178 mm
- Weight: Approx. 2.0 kg
Typical Industrial Applications
The MR-J3-200B is found in active service in multi-axis CNC machine tool systems and automated manufacturing equipment built during the 2005–2015 era when the MELSERVO-J3 SSCNET III platform was Mitsubishi’s primary servo motion control offering. In 3-axis vertical machining centres, the MR-J3-200B commonly drives the X, Y, and Z feed axes where 2 kW per axis provides adequate thrust for medium-weight saddle assemblies at the required rapid traverse speeds and cutting feed forces. Robotic arm axes in medium-payload industrial robots (10–30 kg payload) built on the MELSEC-Q Q173DSCPU motion platform use the MR-J3-200B for the primary rotation and elevation axes, with the full SSCNET III chain synchronisation enabling coordinated multi-axis robot path execution. Packaging machine servo axes — fill station drives, form station drives, and product transfer axes — commonly use the MR-J3-200B in SSCNET III multi-axis systems where the Q172DSCPU motion controller manages the full machine cycle sequence with sub-millisecond axis synchronisation. In active service, the MR-J3-200B typically exhibits its first maintenance requirement after 7–12 years of operation — the capacitors in the DC bus filtering circuit, the cooling fan bearing, and the encoder cable are the primary age-related failure items requiring attention in preventive maintenance programmes for MR-J3-200B fleets.
Maintenance Tips
The MR-J3-200B’s DC bus electrolytic capacitors have a rated service life of approximately 10 years at 40°C ambient — in high-ambient-temperature installations (machine tool spindle motors, foundry equipment), the capacitor life may be significantly shorter. Capacitor degradation manifests as AL.30 (regenerative overvoltage) alarms at normal operation levels, AL.10 (undervoltage) alarms on acceleration, and in advanced cases, visible electrolyte leakage or bulging of the capacitor tops. For MR-J3-200B units approaching 10 years of service, proactive replacement or factory refurbishment should be considered rather than waiting for capacitor failure during production. The cooling fan in the MR-J3-200B has a rated bearing life of approximately 30,000 hours (3.4 years continuous) — in machines running 24/7, fan replacement every 3 years is recommended regardless of observed condition. A cooling fan with degraded bearings produces audible bearing noise before complete failure; schedule fan replacement when bearing noise is first observed rather than waiting for complete failure that causes amplifier overtemperature shutdown. The encoder battery (MR-BAT) in the amplifier should be replaced every 3–5 years — monitor special relay M9030 (battery warning) in the motion controller’s servo program or check the battery voltage via MR Configurator2’s diagnostic screen at each annual maintenance visit.
Frequently Asked Questions
Q: Can MR-J3-200B amplifiers be monitored and diagnosed remotely from the MELSEC-Q motion CPU without a laptop running MR Configurator2 on-site?
A: Yes. The Q172DSCPU or Q173DSCPU motion controller can read servo alarm codes, current values, and status data from connected MR-J3-200B amplifiers via the SSCNET III link using dedicated motion CPU instructions and special relay/register mappings. GX Works2’s motion CPU monitor function can display servo axis status data in real time when connected to the Q-series motion CPU via Ethernet or USB, without requiring a direct USB connection to each individual MR-J3-200B amplifier.
Q: What is the correct procedure for replacing an MR-J3-200B mid-chain without removing other amplifiers from the SSCNET III chain?
A: Power down the entire SSCNET III system (motion controller and all amplifiers) before removing the failed MR-J3-200B. Disconnect the CN1A (input) and CN1B (output) SSCNET III fibre cables, the CN2 encoder cable, the CN3 I/O cable, and the main circuit power and motor power terminals. Install the replacement unit and reconnect all cables in reverse order. Power up the system and write the correct servo parameters to the replacement amplifier using MR Configurator2 before enabling servo operation — the replacement unit ships with factory default parameters that will not match the machine’s tuned servo gains.
Q: Is the MR-J3-200B’s SSCNET III interface compatible with MELSEC iQ-R motion modules?
A: No. MELSEC iQ-R motion modules (RD77MS, RD77GF) use SSCNET III/H protocol, which is incompatible with the MR-J3-200B’s SSCNET III interface. The MR-J3-200B requires a MELSEC-Q series motion CPU (Q172DSCPU, Q173DSCPU) for SSCNET III operation. Migrating an MR-J3-200B-based system to the MELSEC iQ-R platform requires replacing all MR-J3-200B amplifiers with MR-J4-200B simultaneously, as the iQ-R motion module cannot manage MR-J3 amplifiers.
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