Core Calculation Logic Based on Pump Hydraulic Performance
Motor power selection starts with the accurate calculation of pump shaft power, which is derived from the combination of system flow, total head, liquid density and pump efficiency at the designated operating point. The selected motor power must be larger than the maximum shaft power that the pump can generate across its full allowable flow range, rather than only matching the power value at the rated design point. This approach reserves a reasonable safety margin to accommodate unexpected process variations, such as changes in liquid temperature, minor fluctuations in system pressure and slight deviations in actual pipeline resistance from initial design estimates. For most general industrial and municipal water transfer scenarios, the safety margin factor is determined according to the maximum shaft power value, ensuring the motor will not experience sustained overload even when the system operates far outside the initial design parameters. Users should confirm the actual density and viscosity of the transported liquid first, as these two parameters have a direct impact on shaft power calculation and cannot be replaced by the default clean water value for non-water media.

Key Site Conditions That Affect Final Power Sizing
Installation site altitude and ambient temperature are two critical factors that cannot be ignored during motor power selection, as they directly influence the actual continuous output capacity of the motor. At altitudes above 1000 meters, the reduced air density lowers the motor’s natural heat dissipation efficiency, so the rated power of the selected motor must be appropriately increased to avoid overheating under long continuous operation. For sites with sustained ambient temperatures above 40℃, the higher environmental temperature also reduces the effective heat dissipation capacity of the motor, requiring corresponding adjustment to the power selection margin to maintain stable long-term operation. The power supply specifications, including voltage fluctuation range and frequency stability, also need to be fully considered, as large deviations from rated power supply parameters will cause the motor output to drop and potentially lead to unexpected overload during normal operation. Special working conditions such as frequent startup and shutdown, intermittent high-load operation and parallel pump operation in a shared system also require extra attention to ensure the selected motor can handle all possible operating modes without performance degradation.

Compliance with Industry Standards and Operational Safety Requirements
Motor power selection must follow widely recognized industrial specifications that define the minimum required power rating and service factor for different pump operating scenarios. The selected motor must be able to start the pump smoothly under the maximum possible system static pressure, and withstand the transient torque generated during the startup process without damaging internal components. All power sizing decisions must account for all possible power losses in the system, including bearing friction losses, mechanical seal friction losses and any additional losses introduced by connection structures between the motor and pump. For applications that transport flammable, explosive or high-temperature media, the selected motor power must also match the corresponding explosion-proof and heat resistance requirements, ensuring the motor can operate safely under all normal and abnormal working conditions. Every power selection decision should be documented with clear calculation records, so that subsequent operation and maintenance personnel can verify the rationality of the power configuration and make targeted adjustments when the system working conditions change in the future.