The MR-J4-100B is Mitsubishi Electric’s 1 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 6.0 A for Mitsubishi HG-SR and HG-KR series 1 kW servo motors, representing the entry point of the mid-range power class in the MR-J4-B SSCNET III/H sub-series where 1 kW continuous servo power covers the majority of standard machine tool feed axis, robotic wrist axis, and packaging machine servo drive requirements. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the MR-J4-100B?
The MR-J4-100B is a MELSERVO-J4 series servo amplifier providing 1 kW (1,000 W) continuous output power via SSCNET III/H, compatible with Mitsubishi HG-SR102, HG-SR1024, HG-KR13, and equivalent 1 kW servo motors with 22-bit multi-turn absolute encoders. As with all MR-J4-B series amplifiers, all position and speed commands are delivered exclusively via the SSCNET III/H optical fibre link at 0.888 ms or 0.444 ms communication cycle — no pulse train input is present. The MR-J4-100B operates with a single common housing width of 55 mm, consistent with the MR-J4-70B (750 W), making the 100B and 70B the most commonly paired amplifiers in multi-axis systems where different axes require slightly different power levels but panel layout regularity is preferred. The amplifier supports fully closed-loop dual encoder configuration for load-side linear or rotary encoder feedback, enabling position accuracy independent of mechanical compliance between the motor shaft and the load. Built-in STO safety function (IEC 61800-5-2 SIL2, EN ISO 13849-1 PLe), Advanced Vibration Suppression Control II, and 22-bit absolute position retention via the MR-BAT6V1SET battery are standard features.
Key Technical Specifications
- Model: MR-J4-100B
- 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: HG-SR102, HG-SR1024, HG-KR13, HG-KR23B 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: 55 mm
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 55 mm × 170 mm × 165 mm
- Weight: Approx. 1.5 kg
Series Comparison & Selection Guide
Within the MR-J4-B SSCNET III/H sub-series, the 1 kW MR-J4-100B sits at a common crossover point in servo axis specification — it is the smallest power rating that comfortably drives standard 1,000 mm ball screw feed axes in horizontal machining centres at rated rapid traverse speed (typically 20–30 m/min) with normal saddle mass (50–100 kg). Below 1 kW, the MR-J4-70B (750 W) is appropriate for shorter axes or lighter saddle masses; above 1 kW, the MR-J4-200B (2 kW) addresses heavier axis requirements. The MR-J4-100B and MR-J4-70B share the same 55 mm housing width, enabling mechanically consistent panel layouts in 3-axis machines where axes of slightly different power can be installed in adjacent positions. When comparing the MR-J4-100B to the pulse train input equivalent MR-J4-100A, the primary selection factor is the host controller — if the motion controller supports SSCNET III/H (MELSEC-Q Q172DSCPU, iQ-R RD77MS, FX3U-20SSC-H), specify the MR-J4-100B for tighter synchronisation and simpler cabling (single fibre daisy-chain versus individual pulse cables per axis). If the host controller outputs only pulse train (third-party CNC, legacy PLC positioning module), specify the MR-J4-100A. For new machine designs, SSCNET III/H (MR-J4-100B) is the recommended specification as it enables future expansion to higher axis counts and advanced motion functions without hardware changes.
Installation Advice
When installing the MR-J4-100B in a panel alongside other MR-J4-B amplifiers of the same 55 mm width class (MR-J4-70B, MR-J4-200B), maintain a minimum 10 mm clearance between adjacent amplifier housings in the horizontal direction — MR-J4 amplifiers rely on natural convection between units to supplement the internal cooling fan, and insufficient horizontal clearance reduces convection airflow and increases steady-state operating temperature. For the SSCNET III/H optical fibre routing, avoid routing POF cables in the same bundle as motor power cables (U, V, W) — while plastic optical fibre is immune to electromagnetic interference from motor cables, the motor cable heat in a tightly bundled installation can raise the POF cable temperature above its rated operating range (typically 70°C maximum for standard POF), causing increased attenuation and eventual fibre degradation. Route POF cables in a separate cable duct or maintain at least 50 mm separation from motor power cables in open-duct installations. For the MR-J4-100B’s servo motor power cable (CN2 connector), use Mitsubishi’s recommended MR-PWS1CBL motor power cable or equivalent cable rated for flex cycle operation if the motor is mounted on a moving axis — standard fixed-wiring cable used on a moving axis will fatigue and fail at the connector entry point within months of operation at typical axis cycle rates.
Frequently Asked Questions
Q: Can the MR-J4-100B replace an MR-J3-100B directly in an existing SSCNET III motion system?
A: No direct replacement is possible without motion controller consideration. The MR-J4-100B uses SSCNET III/H communication, while the MR-J3-100B uses SSCNET III — both use the same physical POF connector and cable, but the communication protocols are incompatible and cannot coexist on the same chain. Replacing an MR-J3-100B with an MR-J4-100B requires upgrading the motion controller to one supporting SSCNET III/H (Q172DSCPU, Q173DSCPU, or RD77MS) or replacing all amplifiers on the chain simultaneously. The motor can typically be retained during the controller+amplifier upgrade as MR-J4 supports MR-J3 motor compatibility mode.
Q: What is the MR-J4-100B’s position resolution in terms of linear travel per encoder count for a standard 5 mm pitch ball screw?
A: The MR-J4-100B’s 22-bit absolute encoder provides 262,144 counts per motor revolution. With a 5 mm pitch ball screw and a 1:1 coupling ratio, one motor revolution = 5 mm linear travel, giving a linear position resolution of 5 mm ÷ 262,144 = 0.019 µm (19 nanometres) per encoder count. This resolution exceeds the repeatability of standard ball screw assemblies by an order of magnitude — the practical positioning accuracy is limited by the mechanical system (ball screw lead error, backlash, thermal expansion) rather than the encoder resolution.
Q: Does the MR-J4-100B support gear ratio setting for direct-drive rotary table applications?
A: Yes. The MR-J4-100B’s electronic gear ratio parameters (PA06 and PA07 in the servo parameter set) allow the commanded position unit to be scaled to any ratio relative to encoder counts — enabling the motion controller to command positions in degrees or arc-minutes for a rotary table application, with the amplifier internally converting to encoder counts based on the configured gear ratio. This scaling is independent of any mechanical gear ratio and is set in MR Configurator2’s parameter editor.
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