# How To Calculate The Capacity Of Diesel Generator Sets Running In Parallel

Jul. 12, 2022

Due to the different power generation needs of various industries, users often need diesel generator sets to operate in parallel to meet the power supply requirements. So how to calculate the capacity of diesel generator sets running in parallel?

1. The capacity and number of generator sets should be comprehensively determined according to the emergency load size and input sequence, as well as the larger starting capacity of a single motor. When the emergency load is large, multiple units can be used in parallel operation, and the number of units should be 2 to 4 units. When limited by parallel conditions, partition power supply can be implemented. When the power load harmonic is large, its influence on the generator set should be considered.

2. In the preliminary design stage of the scheme, the capacity of diesel generators can be estimated by 10% to 20% of the total capacity of distribution transformers. In the construction design stage, the larger capacity calculated by the following methods can be determined according to the capacity of the primary load, fire protection load and some important secondary loads.

(1) Calculate the capacity of the generator set according to the stable load.

(2) Calculate the diesel generator capacity according to the needs of starting a larger single motor or a group of motors.

(3) Calculate the capacity of the generator set according to the allowable voltage drop of the generator bus when the motor is started.

3. When there is elevator load, in the case of starting a large-capacity cage motor at full voltage, the generator bus voltage should not be lower than 80% of the rated voltage. When there is no elevator load, the bus voltage should not be lower than 75% of the rated voltage. When conditions permit, the motor can be started in an automatic step-down mode. Paralleling can be divided into automatic paralleling and manual paralleling. Usually, automatic paralleling is more accurate and easy to operate. Manual parallel operation is difficult and cumbersome, requiring professional and proficient personnel to operate. It is generally recommended that customers use automatic paralleling. The conditions required for parallel operation are that the engine speed regulation method must be electronic speed regulation, the motor must be a brushless motor, and the frequency, phase, and phase angle must be consistent.

The above is the capacity calculation method for parallel operation of diesel generator sets introduced by Jiangsu Starlight Electricity Equipments Co.,Ltd. If you have any questions, you can consult Jiangsu Starlight Electricity Equipments Co.,Ltd. at any time. We can provide you with one-stop generator set service solutions such as design, supply, commissioning and maintenance.

Founded in 1974, Jiangsu Starlight Electricity Equipments Co.,Ltd. is a wholly-owned subsidiary of Jiangsu Starlight Power Group. It is one of the earliest manufacturers of generator sets in China. Starlight Power has 64 sales and service departments, which provide users with long-term technical advice, free debugging, free maintenance, and free training services. Looking forward to your inquiry, for more details, please contact us with sales@dieselgeneratortech.com.