How To Select Emergency Diesel Generator Set

Jiangsu Starlight Electricity Equipments Co.,Ltd. Guide: The emergency generator set is mainly used in important places. In case of emergency, emergency power failure or instantaneous power failure, the emergency generator set can quickly recover and extend the power supply time for a period of time. This kind of power load is a class I load. For equipment, instruments and computer systems with strict requirements on power off time, in addition to the generator set, storage battery or UPS power supply shall also be provided.

The work of emergency generator set has two characteristics: first, it is urgent, and the continuous working time is not long, generally it only needs to run for a few hours (less than 12h). The second is for standby. The emergency generator set is usually in the state of shutdown and waiting. Only when all the main power supplies fail and are cut off, the emergency generator set will start to operate and supply power for the emergency power load. When the main power supplies are restored, the emergency generator set will switch to shutdown immediately.

(1) Determination of generator capacity of emergency diesel generator set.

The rated capacity of the emergency diesel generator set is the 12h rated capacity after atmospheric correction. Its capacity shall meet the calculated total load of emergency power, and shall be calibrated according to the requirement that the generator capacity can meet the starting requirements of a single motor with the largest capacity in the first level load. The emergency generator is generally three-phase brushless AC synchronous generator with rated output voltage of 400V.

(2) Determination of the number of emergency diesel generator sets.

According to the emergency load capacity, only one emergency diesel generator set is generally set, or more than two units can be selected for parallel operation for power supply. Due to the progress of parallel technology, there are more than 20 parallel applications of diesel generator sets in the emergency standby power supply of the data center. When multiple diesel generator sets are selected, complete sets of equipment with the same model, capacity and similar characteristics of voltage regulation and speed regulation shall be selected as far as possible, and the fuel used shall be consistent in nature, so as to facilitate operation, maintenance and sharing of spare parts. When there are two emergency standby generator units, the self starting device shall enable the two units to be mutually standby, that is, after the delay confirmation of mains power failure, the self starting command will be issued. If the first unit fails to start automatically for three consecutive times, an alarm signal shall be sent and the second unit shall be started automatically.

(3) Selection of emergency diesel generator set.

The diesel generator set with high speed, pressurization, low fuel consumption, high stability and the same capacity should be selected as the emergency unit. High speed and supercharged diesel engines have large single capacity and small floor space. The diesel engine is equipped with electronic speed regulating device, which has good speed regulating performance. The generator should be equipped with brushless excitation synchronous generator.

(4) Control of emergency diesel generator set.

The control of emergency diesel generator set shall be equipped with fast sub startup and automatic input device. When the main power supply is cut off due to failure, the emergency unit shall be able to quickly self start and restore power supply. The allowable power-off time of Class I load ranges from tens of seconds to tens of seconds, which shall be determined according to the actual conditions. When the main power supply of important projects is cut off, there should be a 3-58 confirmation time first, avoiding the instantaneous voltage and the time when the grid is switched on or the standby power is automatically switched on, and then the command to start the emergency generator set should be issued. It will take a period of time for the unit to start, speed up and be able to carry full load from the time the command is issued. Generally, large and medium-sized diesel engines also need pre lubrication and warm-up process to make the oil pressure, oil temperature and cooling water temperature during emergency loading meet the requirements of product technical conditions. Prelubrication and warm-up can be carried out in advance according to different conditions. The unit shall be kept in the pre lubrication and warm-up state at any time, so that it can be quickly started at any time and the time of power failure shall be shortened as far as possible.

After the emergency diesel generator set is put into operation, in order to reduce the mechanical and current impact when sudden load is applied, it is better to increase the emergency load according to the time interval when meeting the power supply requirements. The first allowable load of automatic diesel generator set after successful startup is: for generator set with rated power less than 250kW, the first allowable load is not less than 50% of the rated load. For generator sets with rated power greater than 250kW, the product technical conditions shall apply. If the requirements for transient voltage drop and transition process are not strict, the load of sudden load or sudden load unloading of the general unit should not exceed 70% of the rated capacity of the unit.

Jiangsu Starlight Electricity Equipments Co.,Ltd. is a professional manufacturer of generators, diesel generator sets, Shangchai generator sets, Volvo generator sets, etc. It has 64 sales and service departments, and provides users with one-stop service of design, supply, debugging and maintenance at any time. Welcome the majority of users call for consultation. For more details, please contact us with sales@dieselgeneratortech.com.