The MR-J3-100B is Mitsubishi Electric’s 1 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 servo amplifier from Mitsubishi’s third-generation MELSERVO platform, widely installed in multi-axis CNC machine tool, packaging, and robotic systems and in sustained aftermarket demand for direct maintenance replacement in operational MR-J3 SSCNET III servo systems. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the MR-J3-100B?
The MR-J3-100B is a MELSERVO-J3 series servo amplifier providing 1 kW (1,000 W) continuous output power via SSCNET III optical fibre network — the 1 kW model in the MR-J3-B SSCNET III sub-series, compatible with Mitsubishi HC-SFS102, HC-RFS103, and equivalent 1 kW servo motors equipped with the MR-J3’s 17-bit multi-turn absolute encoder (131,072 pulses/rev). The «B» suffix designates the SSCNET III network variant — the MR-J3-100B receives all position and speed commands exclusively via SSCNET III plastic optical fibre at 0.888 ms communication cycle time from compatible MELSEC-Q motion controllers (Q172DSCPU, Q173DSCPU). Unlike the current-generation MR-J4-100B which uses SSCNET III/H (150 Mbps full-duplex), the MR-J3-100B uses SSCNET III (10 Mbps, half-duplex in command direction) — the two protocols are physically identical (same POF connector and cable) but electrically incompatible, and MR-J3 and MR-J4 amplifiers cannot share the same SSCNET chain. The MR-J3-100B does not include a built-in STO safety function — safety compliance requires external safety contactors in the main circuit wiring. The MR-J3-100B has been superseded by the MR-J4-100B and should be specified for direct maintenance replacement only.
Key Technical Specifications
- Model: MR-J3-100B
- Rated Output Power: 1 kW (1,000 W)
- Power Supply: 200–240 VAC single-phase or three-phase, 50/60 Hz
- Continuous Output Current: 6.0 A
- Maximum Output Current: 18.0 A (3× continuous peak)
- Compatible Servo Motors: HC-SFS102, HC-RFS103, HC-KFS13B (J3 gen), HG-SR102 (J4 motor, J3 compat.)
- Command Interface: SSCNET III optical fibre (10 Mbps half-duplex in command direction)
- 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
- Communication: USB (MR Configurator2), RS-422 (parameter cascade)
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 55 mm × 170 mm × 165 mm
- Weight: Approx. 1.5 kg
Compatibility & System Integration
The MR-J3-100B operates exclusively on SSCNET III networks managed by MELSEC-Q motion controllers — specifically the Q172DSCPU (up to 32 axes), Q173DSCPU (up to 96 axes), and Q170MCPU motion controllers. It is not compatible with the MELSEC iQ-R RD77MS or other SSCNET III/H controllers — the MR-J3-100B requires the older SSCNET III communication, available only on Q-series motion CPUs. In a SSCNET III multi-axis chain, the MR-J3-100B can coexist with other MR-J3-B amplifiers of different power ratings (MR-J3-70B, MR-J3-200B, MR-J3-350B) — all MR-J3-B variants use identical SSCNET III communication. MR-J4-B amplifiers cannot be mixed into the same chain as MR-J3-B amplifiers due to the SSCNET III / SSCNET III/H protocol incompatibility. The MR-J3-100B is compatible with current-generation HG-SR102 and HG-KR13 servo motors (MR-J4 standard motors) when parameter PA22 is set to enable motor compatibility mode — this enables motor-only upgrades to current-generation motors while retaining the MR-J3-100B amplifier. For parameter configuration and servo tuning, MR Configurator2 (current Mitsubishi commissioning tool) fully supports the MR-J3-100B via USB connection, providing the same parameter access, auto-tuning, and waveform monitoring functions available for MR-J4 amplifiers.
Replacement & Upgrade Notes
The MR-J3-100B has been discontinued from Mitsubishi production and is sourced from aftermarket inventory. For direct maintenance replacement, verify the supplier’s warranty and authenticity — genuine MR-J3-100B units are identifiable by the Mitsubishi serial number format and firmware version visible in MR Configurator2 after USB connection. When a direct MR-J3-100B replacement cannot be sourced, or when proactive fleet upgrade is planned, the MR-J4-100B is the upgrade path — providing 22-bit encoder resolution, built-in STO, AVSC II, and 0.444 ms SSCNET III/H communication. However, upgrading from MR-J3-100B to MR-J4-100B requires upgrading the motion controller simultaneously (from Q172DSCPU/Q173DSCPU SSCNET III to Q172DSCPU/RD77MS SSCNET III/H), or replacing all amplifiers in the SSCNET chain at once — individual amplifier replacement within a mixed J3/J4 chain is not possible. For facilities with large installed fleets of MR-J3-100B amplifiers, Mitsubishi recommends a planned complete chain migration (controller + all amplifiers simultaneously) during a scheduled production shutdown rather than reactive one-for-one replacements, to avoid the operational disruption of multiple partial upgrades. Use MR Configurator2’s parameter conversion function to translate the existing MR-J3 servo parameter files to MR-J4 format before the migration, verifying the converted parameters against the original machine setup documentation.
Frequently Asked Questions
Q: What MELSEC-Q motion controllers are compatible with the MR-J3-100B’s SSCNET III interface?
A: The MR-J3-100B requires a SSCNET III (not SSCNET III/H) motion controller. Compatible controllers include the Q172DSCPU (32 axes), Q173DSCPU (96 axes), Q170MCPU (8 axes), and the Q172CPU/Q173CPU (older models). SSCNET III/H controllers (Q172DSCPU with SSCNET III/H upgrade, RD77MS) are incompatible with the MR-J3-100B. Verify the specific Q-series motion controller’s SSCNET version before attempting to connect an MR-J3-100B.
Q: Can the MR-J3-100B’s absolute position be retained without the encoder battery during short power-off periods?
A: The MR-J3-100B relies on the encoder battery (MR-BAT) to retain the absolute multi-turn position counter during power-off. There is no supercapacitor backup in the MR-J3 encoder system — removing the battery or allowing it to deplete causes immediate loss of the absolute multi-turn position, requiring a homing cycle at next power-up. The encoder battery should be installed at all times during normal operation and replaced every 3–5 years depending on ambient temperature.
Q: Can an MR-J3-100B that was working correctly in one machine be transferred to replace a failed unit in a different machine?
A: Yes, with parameter reconfiguration. The MR-J3-100B stores machine-specific servo parameters in its non-volatile internal memory — a unit transferred from one machine to another retains the previous machine’s parameter settings. Before operating the transferred unit in the new machine, write the new machine’s correct servo parameters to the amplifier using MR Configurator2. Operating with incorrect gain parameters can cause servo instability, excessive vibration, or AL.50 overload alarms due to mismatched servo tuning for the new machine’s mechanical system.
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