The HG-RR103K is Mitsubishi Electric’s 1 kW medium-inertia medium-capacity servo motor from the HG-RR series for the MELSERVO-J4 servo amplifier platform, providing 3.18 N·m rated torque at 3,000 rpm with a 22-bit multi-turn absolute encoder as standard — the 1 kW model in the HG-RR medium-inertia series, designed for servo axis applications where a higher rotor inertia relative to the HG-SR low-inertia series provides improved load-side inertia matching, smoother velocity regulation at varying load torque, and reduced sensitivity to load inertia fluctuations in applications such as conveyor drives, winding systems, and variable-load rotary axes. Atlantech Drives holds stock of the HG-RR103K. Contact us for fast worldwide delivery and competitive pricing.
What Is the HG-RR103K?
The HG-RR103K is a Mitsubishi Electric MELSERVO HG-RR series servo motor providing 1 kW (1,000 W) continuous rated output at 3,000 rpm rated speed, with a peak torque of 9.55 N·m (3× rated torque). The «RR» series designation identifies the medium-inertia medium-capacity motor family — as distinct from the «SR» low-inertia series — reflecting a higher rotor inertia per unit output power that naturally damps velocity disturbances from load torque variations, at the cost of slightly lower acceleration response compared to equivalent-power HG-SR motors. The «K» suffix in the model designation indicates the motor is compatible with MR-J4-100A and MR-J4-100B servo amplifiers using the «K» motor parameter set — verify that the servo amplifier’s motor code selection includes the HG-RR103K code in MR Configurator2 before commissioning. The 22-bit multi-turn absolute encoder provides 262,144 pulses/rev resolution, with multi-turn position retention across power cycles via the MR-BAT6V1SET battery in the servo amplifier.
Key Technical Specifications
- Model: HG-RR103K
- Rated Output Power: 1 kW (1,000 W)
- Rated Torque: 3.18 N·m
- Rated Speed: 3,000 rpm
- Maximum Speed: 4,500 rpm
- Peak Torque: 9.55 N·m (3× rated)
- Rotor Inertia: 1.38 × 10⁻⁴ kg·m² (higher than HG-SR102’s 0.54 × 10⁻⁴ kg·m²)
- Encoder: 22-bit multi-turn absolute (262,144 pulses/rev)
- Power Supply Voltage: 200 VAC (via compatible servo amplifier)
- Insulation Class: F (155°C maximum winding temperature)
- Protection Rating: IP65 (shaft seal and connector side)
- Mounting: Square flange, IEC standard
- Operating Temperature: 0°C to 40°C (ambient)
- Weight: Approx. 3.8 kg
Series Comparison & Selection Guide
Within Mitsubishi’s MELSERVO HG series motor range, the HG-SR and HG-RR series address different inertia class requirements at the same power levels. At 1 kW, the HG-SR102 (low inertia, 0.54 × 10⁻⁴ kg·m²) and the HG-RR103K (medium inertia, 1.38 × 10⁻⁴ kg·m²) both provide 1 kW continuous output but with different dynamic characteristics. The HG-SR102 provides faster acceleration response and is appropriate for applications requiring rapid position changes at low load inertia ratios — pick-and-place machines, semiconductor handling, high-speed indexing. The HG-RR103K’s higher rotor inertia provides better velocity regulation under varying load torque and improved inertia matching for applications with moderate-to-high load inertia — conveyor drives, rotary table drives, winding tension control, and any application where the load inertia is large relative to the motor inertia and the HG-SR series would result in an unacceptably high inertia ratio. The general servo sizing rule for inertia ratio recommends keeping the load-to-motor inertia ratio below 30:1 for standard applications — if a 1 kW HG-SR102 results in an inertia ratio above 30:1 for the specific mechanical system, specifying the HG-RR103K with its 2.5× higher rotor inertia reduces the ratio proportionally, potentially bringing the system within the recommended servo tuning range without requiring a larger motor frame.
Replacement & Upgrade Notes
The HG-RR103K is the current-generation MELSERVO-J4 equivalent for applications previously using MR-J3-era HC-RFS103 motors (medium-inertia, 1 kW, 3,000 rpm) — the HG-RR103K provides the same medium-inertia characteristic as the HC-RFS103 with the upgrade to 22-bit absolute encoder resolution from the J3-era 17-bit encoder. For MR-J3-based installations where an HC-RFS103 motor has failed, the HG-RR103K can be used as a direct motor replacement with the existing MR-J3-100A or MR-J3-100B amplifier in J4 motor compatibility mode (parameter PA22 = 1) — the encoder cable must be replaced with an HG-RR-compatible cable (MR-J3ENCBL series), as the HC-RFS103 encoder cable is physically incompatible with the HG-RR103K encoder connector. The servo gains may require adjustment after installing the HG-RR103K in place of an HC-RFS103, as the higher rotor inertia of the new motor changes the servo system’s dynamic response relative to the original motor — re-run auto-tuning in MR Configurator2 with the HG-RR103K installed to establish appropriate gain settings for the new motor. For completely new servo system designs requiring a 1 kW medium-inertia motor, verify that the load-to-motor inertia ratio with the HG-RR103K is within the acceptable range before finalising the motor selection — if the inertia ratio is still above 30:1 with the HG-RR103K, a larger motor frame (HG-RR203K at 2 kW) should be considered to further reduce the inertia ratio.
Frequently Asked Questions
Q: What specific applications benefit most from the HG-RR103K’s medium inertia compared to the HG-SR102’s low inertia at the same 1 kW power?
A: The HG-RR103K is most beneficial in applications where: (1) the mechanical load inertia is large compared to typical J4-era servo motor inertia, creating an inertia ratio above 30:1 with the HG-SR102; (2) the application involves non-uniform load torque (varying cutting forces, product weight variations on a conveyor, web tension fluctuations in a winding system) where the higher rotor inertia of the HG-RR103K acts as a flywheel to smooth velocity variations; or (3) the servo system must be stable with very high servo response bandwidth that the lower-inertia HG-SR102 cannot achieve without exciting mechanical resonances.
Q: Does the HG-RR103K require a different servo amplifier than the HG-SR102 at the same 1 kW power rating?
A: No. Both the HG-RR103K and the HG-SR102 are compatible with the same MR-J4-100A and MR-J4-100B servo amplifiers. The distinction between the two motors is handled by the motor code parameter in the servo amplifier (set via MR Configurator2) — select the HG-RR103K motor code from the amplifier’s supported motor list to configure the correct back-EMF constant, rated current, and inertia reference values for the HG-RR103K.
Q: Is the HG-RR103K suitable for high-cycle pick-and-place applications requiring very fast acceleration and deceleration?
A: The HG-RR103K’s higher rotor inertia (1.38 × 10⁻⁴ kg·m² versus 0.54 × 10⁻⁴ kg·m² for the HG-SR102) requires more energy to accelerate and decelerate the rotor itself — this means the HG-RR103K will achieve lower acceleration than the HG-SR102 at the same peak torque for applications where rotor inertia dominates. For high-cycle pick-and-place applications where maximum acceleration is the primary metric, the HG-SR102 (low inertia) is the preferred specification. The HG-RR103K is more appropriate for moderate-cycle applications where load matching and velocity stability are prioritised over absolute acceleration performance.
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