0.4kV发电机保护配置有：短路保护；欠电压保护；过电流保护；发电机�功率保护；发电机�?欠频率保护；发电机超负荷保护�?/DIV>
The 0.4kV alternator is configured with these protective functions covering short circuit, over current, reverse power of alternator, over or under frequency and overload of alternator.
短路保护：利用主回路低压智能断路器做短路保护，短路动作电流整�?-10倍额定电流�
Short circuit protection: The intelligent breaker in the main loop functions short circuit protection, and the setting point of short circuit protection is 8 to 10 times of the rated current of alternator.
过电流保护：利用主回路低压智能断路器的短延时保护，按照发电机额定电流�?.25倍整定�
Over current protection: The intelligent breaker in the main loop functions momentary delay protection, and the setting point is 1.25 times of the rated current of alternator.
欠电压保护：在主回路低压智能断路器装设欠压脱扣器，当发电机电压低�?0%-60%额定电压时，使主断路器分闸�
Under voltage protection: The under voltage tripping device is installed with the intelligent breaker in the main loop. While alternator voltage is below 50% to 60% of rated voltage, the main breaker shall open.
逆功率保护：并联运行时发�?%-15%额定功率的�功率时，10s内�功率保护装置使主断路器分闸�
Reverse power protection: The reverse power protection shall open in 10 minutes????? when generator set operates in parallel at reverse power equivalent to 5% to 15% of rated power.
发电机热保护(用户要求时��?：定子温度超�?45℃，发出声光报警，并使主断路器分闸�
Heat protection of alternator (optional by customer): If the alternator stator is above 145�? the protection sends out an acousto-optic alarm and makes the main breaker open.
3.8.3 连接电缆
Connecting cable
发电机至断路器屏的主电缆及断路器屏至机组房采集与继电控制屏的电缆，建议用户根据机组功率大小�用��?KV的低压电力电缆，不属于我厂的标准供货范围，为用户选购件，订货时请注意�?/DIV>
It is recommended to choose the 1kV low-voltage cable to connect alternator to breaker panel as well as breaker panel to collecting and relay control panel. If the required cable is not in the list of the product supply by our company, it is optional for customer to purchase. Please pay much attention while ordering.
3.8.4 用户对机组供电的要求
Requirement for gen-set power supply by customers
根据用户使用情况的不同，对发电机组运行方式的要求也存在差异，一��有以下几种情况：
For the generator set services customer in different conditions, it should operate in different way, which is described in detailed as follows.
1�?单台机组独立带载运行，不并机不并网�
Single generator set shall operate independently with load, which is not in parallel with other generator sets and not connected to electric grid.
2�?单台或多台机组与电网并网运行，不并机�?/DIV>
Single generator set or several generator sets shall operate in connection to electric grid, which is not in parallel with other generator sets.
3�?多台机组并机运行不并网�
Several generator sets operate in parallel but not connected to electric grid.
4�?电网无电时多台机组并机运行，电网恢复供电后机组并网运行�
When electric grid fails, several generator sets operate in parallel, and then are connected to the electric grid after electric grid recoveries.
3.8.4.1 单台机组独立带载运行
Single generator set operating with load independently
一��在一些偏远地区架设市电电网成本很高，或用户根据情况需要单台机组供电，如作为工厂的应�电站只需带动应�部分负荷，则可以采用单台机组供电的方式�
It is recommended that single generator set shall be mounted to output power in rural areas or in factories as emergent power plant or for these customers who need only one generator set to output power. In the rural areas, it is too expensive to install public electric grid individually.
单台机组供电，存在一些问题，主要有：
Power generation by single generator set shall follow with the disadvantages.
1）机组检修或发生故障时用户就需��停电，供电连续�差�
It is to fail to supply power continuously when the generator set has to stop for repair and maintenance or troubled
2）因单台发电机的容量有限，因此它带负载能力有限�
Single generator set shall only be loaded limitedly for the capacity of single alternator
3）负荷变化时发电机的频率及端电压都会受到影响，不能保证供电质量�
When load is variable, there is influence on frequency and terminal voltage of alternator as well as quality of power supply.
4)不能充分发挥发电机组的潜能，无法实现供电的灵活�和经济��?/DIV>
The generator set fails to show its actual ability completely, losing its flexibility and economic advantages.
这些问题可以通过多台机组并机运行来改善�
The disadvantages may be removed greatly when several generator sets operates in parallel.
3.8.4.2 单台或多台机组与电网并网运行，不并机
Single generator set or several generator sets shall operate in connection to electric grid, which is not in parallel with other generator sets.
电网对单台发电机或某个工厂负荷来说可视为无穷大电网或无穷大汇流排，即电网容量可视为无穷大。单台发电机的投入与退��，个别负载的变化，对电网的影响甚微，衡量供电质量的电压和频率可视为恒定不变的常数。同步发电机并联到电网后，它的运行情况要受到电网的制约，也就是说它的电压、频率要和电网一致�不能单独变化�?/DIV>
Electric grid is considered as an infinite or collecting bar relative to single generator set or load in factory, and it means that capacity of electric grid is infinite. Single generator set connected or disconnected with the grid and load fluctuation shall have an effect on the electric grid slightly, and so voltage and frequency rated to power quality is considered as a changeless constant. After the synchronous alternator is connected to electric grid, its voltage and frequency should always conform to that of electric grid without any change for operations of generator set is controlled by the grid.
机组并网运行优点很多�?/DIV>
Advantages of generator set operation if connected to grid:
1）提高了供电的可靠�，机组发生故障或定期检��不会引起停电事故�?/DIV>
It shall output power much reliably, and it does not fail to supply power once the generator set is troubled or has to stop for periodic repair or maintenance.
2）可以充分利用当地资源，使每台机组长期按额定功率运行，充分发挥发电机组的潜能�?/DIV>
It should be better to utilize the local gas resources efficiently and keep every generator set operating at rated power in best conditions.
3）缓解当地供电的紧张局��。对于一个开放式电力网络，如果单台发电机组的额定功率或�多台发电机组的额定功率�和大于本地的最��负载功率，则可以通过与市电电网并联，将多余的电能输�到市电网络，对当地的市电电网进行补充，缓解当地供电紧张状况�
机组只并网运行时，当电网停电时机组应立即与电网解列停机，这一点我们一般�过电网失电检测�欠频、过流等保护措施来实现�
It shall be helpful for the areas lack of electric power. For an open electric grid, redundant power from generator sets may be transmitted to local public electric grid and give a supplement when single or several generator sets operates at higher rated power than local load. If generators set is only connected to grid while operating, please disconnect it with electric grid promptly once the grid fails, which shall be actuated by the protective measures on the gen-set control system including power failure measurement, under frequency and over current and others.
3.8.4.3 多台机组并机运行
Several generator sets operating in parallel
并机运行是指通过并联将几台发电机所��的电联成一��独立的供电网络�电力系统中，一��稳定的电力网络一般情况下都是由多台同步发电机并联起来接在共同的汇流排�?见图3.1)，因此，如果用户需��一��稳定的独立于外界的供电网络，一��情况下也需��将多台发电机组并机运行，组成一��电力网络，提高供电质量�这些并机运行的机组组成的供电网络一��也称为孤岛式电站�?/DIV>
Operation of several generator sets in parallel means to integrate power from several generator sets to form an individual power supply network. In general, a stable power network in a power system is established by several synchronous alternators in parallel which are connected to a common collecting bar ( please refer to fig 3.1). If customer needs a reliable power supply network independent of outside power network, it is necessary to operate the several generator sets in parallel to make a power network so as to obtain a high quality power supply. This above-mentioned power network is now called stand-alone power plant.
