The HG-SR302 is Mitsubishi Electric’s 3 kW low-inertia medium-capacity servo motor from the HG-SR series for the MELSERVO-J4 and MELSERVO-J3 servo amplifier platforms, providing 14.3 N·m rated torque at 2,000 rpm with a 22-bit multi-turn absolute encoder as standard — a high-torque variant in the HG-SR series operating at lower rated speed than the 3,000 rpm standard models, designed for heavy-load direct-drive conveyor axes, rotary indexing tables with large dial masses, and machine tool feed drives where high sustained torque at moderate shaft speed is the primary axis requirement. The HG-SR302 is available through Atlantech Drives — quote within 24-48 hours, worldwide express shipping, 12-month warranty.
What Is the HG-SR302?
The HG-SR302 is a Mitsubishi Electric MELSERVO HG-SR series servo motor providing 3 kW (3,000 W) continuous rated output at 2,000 rpm rated speed — the «2» at the end of the model number designates the 2,000 rpm rated speed variant within the 3 kW power class, as distinct from the HG-SR302’s sibling HG-SR352 which provides 3.5 kW at 3,000 rpm. At 14.3 N·m rated torque (versus 11.1 N·m for the 3,000 rpm HG-SR352 at the same power level), the HG-SR302’s lower rated speed winding provides higher torque at lower speed — valuable for applications where the load torque is high at the working speed but the required shaft speed does not approach 3,000 rpm, enabling direct drive or shorter gear ratio connections that reduce drivetrain complexity and backlash. The HG-SR302 is compatible with MR-J4-350A (pulse train) and MR-J4-350B (SSCNET III/H) servo amplifiers and, in J3 motor compatibility mode, with MR-J3-350A and MR-J3-350B amplifiers. The 22-bit multi-turn absolute encoder provides the same 262,144 pulses/rev position resolution as all HG-SR series motors, with the multi-turn absolute count retained across power cycles by the MR-BAT6V1SET battery in the servo amplifier.
Key Technical Specifications
- Model: HG-SR302
- Rated Output Power: 3 kW (3,000 W)
- Rated Torque: 14.3 N·m
- Rated Speed: 2,000 rpm
- Maximum Speed: 3,000 rpm
- Peak Torque: 42.9 N·m (3× rated)
- Rotor Inertia: 2.58 × 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. 9.5 kg
Series Comparison & Selection Guide
Within the HG-SR series 3 kW power class, two primary variants exist: the HG-SR302 (3 kW, 2,000 rpm rated, 14.3 N·m rated torque) and the HG-SR352 (3.5 kW, 3,000 rpm rated, 11.1 N·m rated torque). The selection between these models depends on the application’s torque-speed operating point. The HG-SR302 is the correct choice when the required shaft torque at the working speed falls in the 10–14 N·m range at speeds below 2,000 rpm — the 2,000 rpm winding provides higher torque per watt at low speed compared to the 3,000 rpm winding, enabling direct drive or shorter gear ratio use where the 3,000 rpm variant would require a higher gear ratio to develop adequate torque at the working speed. The HG-SR352 is appropriate when the required working speed approaches 3,000 rpm — the higher rated speed winding is more efficient at speeds above 2,000 rpm. For applications where the load operates across a wide speed range (from near-zero to maximum), the 2,000 rpm HG-SR302 provides better low-speed torque coverage while the 3,000 rpm HG-SR352 provides a higher maximum speed ceiling. Comparing HG-SR302 to the next larger motor in the standard 3,000 rpm sub-series: the HG-SR502 (5 kW, 3,000 rpm) provides similar torque to the HG-SR302 at higher speed but requires a larger amplifier (MR-J4-500A/B). For applications where 3 kW at 2,000 rpm matches the duty cycle, the HG-SR302 + MR-J4-350A/B pairing is more economical than the HG-SR502 + MR-J4-500A/B combination.
Installation Advice
The HG-SR302 at 3 kW and 9.5 kg requires secure mounting on a rigid, flat mounting surface capable of supporting the motor weight and the shaft reaction forces without deflection. The mounting flange bolt pattern must be fully utilised — all four mounting bolts tightened to the specified torque in the HG-SR series hardware manual — as under-torqued or missing mounting bolts allow the motor body to shift under the high peak torque (42.9 N·m) generated during rapid acceleration, causing progressive position offset. Use thread-locking compound (medium strength Loctite 243 or equivalent) on the mounting bolts in high-vibration installations to prevent bolt loosening over time. For the HG-SR302’s motor power cable (rated for the MR-J4-350A/B’s motor output at 3.5 kW), use Mitsubishi’s recommended MR-PWS1CBL power cable or equivalent cable rated for flex cycle operation if the motor is on a moving axis — standard rigid installation cable is not suitable for moving axis applications and will fatigue at the motor connector within months. The HG-SR302’s 14.3 N·m rated torque at 2,000 rpm corresponds to significant shaft torque that can loosen improperly secured shaft couplings — use a shaft coupling with a keyway and set screw (or a hydraulic clamping coupling) rather than a friction-only coupling on the 3 kW HG-SR302 to prevent coupling slip under peak torque loading. Measure the coupling tightening torque with a torque wrench and verify against the coupling manufacturer’s specified clamping force before operating the servo axis at rated torque.
Frequently Asked Questions
Q: Why is the HG-SR302 rated at 2,000 rpm rather than 3,000 rpm like most other HG-SR models?
A: The 2,000 rpm rating of the HG-SR302 reflects a different stator winding configuration — more turns of smaller gauge wire compared to the 3,000 rpm HG-SR352 winding — that produces higher torque at lower speed from the same permanent magnet rotor and frame. This winding trade-off provides 14.3 N·m at 2,000 rpm versus 11.1 N·m at 3,000 rpm for the same 3 kW power, enabling the HG-SR302 to drive loads that require more than 11 N·m at moderate speeds without requiring a gear reducer. The maximum speed is also lower (3,000 rpm versus 5,000 rpm) because the higher winding inductance limits the back-EMF ceiling speed.
Q: Can the HG-SR302 be used with a harmonic drive (strain wave gearing) for precision rotary axis control?
A: Yes. The HG-SR302’s low-inertia classification makes it well suited for use with harmonic drive gearboxes — the motor’s low rotor inertia relative to the reflected load inertia through the harmonic drive ratio keeps the inertia ratio within the servo amplifier’s recommended range even at high gear ratios (100:1 or higher). The harmonic drive’s zero-backlash characteristic complements the HG-SR302’s 22-bit encoder resolution, enabling nanometre-class positioning accuracy at the harmonic drive output shaft. Set the servo amplifier’s electronic gear ratio (PA06/PA07) to reflect the harmonic drive gear ratio so that the motion controller’s commanded positions in output shaft degrees correspond correctly to the motor encoder counts.
Q: What is the allowable radial shaft load for the HG-SR302, and is direct belt drive connection supported?
A: The HG-SR302’s allowable radial shaft load is specified in the HG-SR series hardware manual (typically in the range of 490–980 N at rated speed, at a position 20 mm from the shaft end, depending on the specific load application point). For belt drive connections, calculate the actual belt tension at the motor shaft and verify it is within the allowable radial load specification, accounting for both the tension force and the wrap angle geometry. The HG-SR302’s 9 mm shaft diameter (typical for this frame size) accepts standard IEC servo motor shaft-mounted belt pulleys — verify the pulley bore and keyway specification against the HG-SR302 shaft dimensions in the hardware manual before ordering pulleys.
Do you need more references from this brand? Explore our full catalog of Mitsubishi here: https://atlantechdrives.com/manufacturers/mitsubishi/
