I. Why Hydraulic Power Station Motor Power Cannot Be Determined Arbitrarily

In hydraulic system integration projects, motor power selection directly impacts system energy efficiency, temperature rise control, long-term stability, and even equipment service life. Having served numerous injection molding machine manufacturers and metallurgical production lines, we have observed cases where undersized motors caused continuous hydraulic pump overload and excessive oil temperature rise—and others where oversized motors led to 'overpowered underutilization', increasing energy consumption by over 15% and degrading system responsiveness. As a hydraulic manufacturing enterprise based in Shishan, Nanhai District, Foshan for nearly 22 years (Foshan Liqiang Hydraulic & Electro-Mechanical Equipment Co., Ltd.), we firmly adhere to this principle: custom hydraulic cylinder design and hydraulic power station engineering must begin with precise motor power calculation.

II. Core Calculation Formula: Theoretical Power + Three Efficiency Corrections

1. Basic Formula (Unit: kW)

Required motor output power:
Pmotor = Phyd / (ηpump × ηtrans × ηmotor)

Where:
• Phyd = (p × Q) / 600 (p: system working pressure in bar; Q: rated flow rate in L/min)
• ηpump: total hydraulic pump efficiency (gear pumps: ~0.80–0.85; piston pumps: 0.85–0.92—refer to specific hydraulic pump datasheets)
• ηtrans: coupling/belt transmission efficiency (direct drive: 0.98; flexible coupling: 0.95–0.97)
• ηmotor: motor efficiency (IE3 high-efficiency motors typically 0.88–0.94—verify via nameplate)

2. How to Obtain Key Parameters: Liqiang Hydraulic’s Practical Recommendations

  • Pressure p: Do not simply use the relief valve setting. Instead, analyze inlet pressure of hydraulic components under maximum load conditions—including pipeline friction losses—and add 10–15% safety margin.

  • Flow Q: Calculate based on the highest required actuator speed, plus a synchronization factor for multiple actuators (e.g., multiply Q by 1.1–1.3 for dual-cylinder synchronization).

  • Efficiency η: Avoid generic estimates! Liqiang Hydraulic provides a pump-valve matching report for every hydraulic system integration solution, precisely specifying pressure drop of selected hydraulic valves and viscosity-related pump efficiency impacts.

III. Critical Engineering Variables: Temperature, Intermittency & Safety Factor

In Foshan’s high-temperature, high-humidity environment, motor cooling capacity declines. We recommend:
• For continuous-duty systems: apply a safety factor of 1.15–1.25 to calculated results;
• For short-time repetitive loads (e.g., machine tool clamping/unclamping cycles): use equivalent thermal power method and verify per S3 or S6 duty cycle;
• For closed-loop control stations with proportional or servo valves: account for peak control signal power demand—Liqiang Hydraulic commonly equips metallurgical clients with VFD + soft-start modules to reduce inrush current.

IV. Typical Misapplication Cases

❌ Mistake 1: Calculating pressure solely from cylinder thrust, ignoring pressure drops across flow control valves and stack-type hydraulic valves (a single proportional flow control valve may incur 5–8 bar loss);
❌ Mistake 2: Simply summing peak flows of multiple machines sharing one hydraulic power station, without accounting for operational sequence overlap;
❌ Mistake 3: Applying efficiency values for imported piston pumps to domestic low-efficiency vane pumps—leading to chronic motor overheating and shutdown. This was the root cause identified during our retrofit of an old station for a Dongguan injection molding plant.

V. Liqiang Hydraulic Professional Support: From Calculation to Implementation

Since establishment in 2002, Liqiang Hydraulic has specialized in Foshan hydraulic manufacturing, delivering reliable solutions to over 2,800 customers. Beyond standard hydraulic components, we excel at:
✓ Full-system power simulation and thermal balance analysis based on customer application drawings;
✓ Custom custom hydraulic cylinder for special environments (e.g., 150°C-rated cylinders for high-temperature metallurgy; clean-room injection molding cylinders with zero-leakage cushioning);
✓ Modular hydraulic power station design integrating cooling, filtration, and intelligent monitoring units;
✓ Turnkey hydraulic system integration services, including on-site commissioning and operator training.

Act Now: Let Professional Calculation Save Your First Kilowatt-Hour

A 1 kW motor power discrepancy may cost over RMB 3,000 annually in electricity (at RMB 0.8/kWh, 6,000 operating hours/year). Stop relying on experience-based estimation!
Submit your equipment operating parameters (pressure/flow/cycle time), on-site photos, or CAD drawings. Liqiang Hydraulic’s technical team will provide free motor power verification, pump-valve selection recommendations, and a detailed quotation within 24 hours.
📍 Address: Unit 204, Building 5, Phase II, Nanyang Wanyang Zhongchuang City, Xiaotang Industrial Avenue 82, Shishan Town, Nanhai District, Foshan
📞 Technical Service Hotline: +86 13929911716