1. Generator non synchronous parallel

发电机用准同期法并列时，应满足电压、频率、相位相同这3个条件，造成并车失败,如果由于操作不当或其它原因，并列时没有满足这3个条件，发电机就会非同期并列，它可能使发电机损坏，并对系统造成强烈的冲击，因此应注意防止此类故障的发生。 当待并发电机与系统的电压不相同，其间存有电压差，在并列时就会产生一定的冲击电流。

When the generators are paralleled by quasi synchronous method, the three conditions of the same voltage, frequency and phase shall be met, resulting in the failure of parallel operation. If these three conditions are not met in parallel due to improper operation or other reasons, the generator will be out of synchronization parallel, which may damage the generator and cause strong impact on the system. Therefore, attention should be paid to prevent the occurrence of such faults. When the voltage of the generator to be paralleled is different from that of the system, there is a voltage difference between them, and a certain impulse current will be generated when the generator is paralleled.

一般当电压相差在±10%以内时，冲击电流不太大，对发电机也没有什么危险。如果并列时电压相差较多，特别是大容量电机并列时，如果其电压远低于系统电压，那么在并列时除了产生很大的电流冲击外，还会使系统电压下降，可能使事故扩大。一般在并列时，应使待并发电机的电压稍高于系统电压。

Generally, when the voltage difference is within ± 10%, the impulse current is not too large and there is no danger to the generator. If there are many voltage differences in parallel, especially when large capacity motors are paralleled, if the voltage is far lower than the system voltage, in addition to producing a great current impact, the system voltage will drop and the accident may be expanded. In general, the voltage of the generator to be paralleled should be slightly higher than the system voltage.

如果待并发电机电压与系统电压的相位不同，并列时引起的冲击电流将产生同期力矩，使待并发电机立刻牵入同步。如果相位差在±300以内时，产生的冲击电流和同期力矩不会造成严重影响。如果相位差很大时，冲击电流和同期力矩将很大，可能达到三相短路电流的2倍，它将使定子线棒和转轴受到一个很大的冲击应力，可能造成定子端部绕组严重变形，联轴器螺栓被剪断等严重后果。 为防止非同期并列，有些厂在手动准同期装置中加装了电压差检查装置和相角闭锁装置，以保证在并列时电差、相角差不超过允许值。

If the phase of the voltage of the generator to be paralleled is different from that of the system voltage, the impulse current caused by the paralleling will produce the synchronous torque, which makes the generator to be synchronized immediately. If the phase difference is within ± 300, the impact current and synchronization torque will not be seriously affected. If the phase difference is very large, the impact current and synchronous torque will be very large, which may be twice of the three-phase short-circuit current. It will make the stator bar and shaft subject to a large impact stress, which may cause serious deformation of the stator end winding and serious consequences such as coupling bolt being cut off. In order to prevent non synchronous parallel operation, some factories have installed voltage difference checking device and phase angle locking device in manual quasi synchronization device to ensure that the electric difference and phase angle difference do not exceed the allowable value when paralleling.

2、发电机温度升高

2. Generator temperature rise

(1)定子线圈温度和进风温度正常，长期过载,局部线卷有短路,通风不畅,而转子温度异常升高，这时可能是转子温度表失灵，应作检查。发电机三相负荷不平衡超过允许值时，也会使转子温度升高，此时应立即降低负荷，并设法调整系统已减少三相负荷的不平衡度，使转子温度降到允许范围之内。

(1) The temperature of stator coil and inlet air temperature are normal, long-term overload, short circuit of local coil, poor ventilation, and abnormal rise of rotor temperature. At this time, the rotor thermometer may be out of order, so it should be checked. When the three-phase load unbalance of the generator exceeds the allowable value, the rotor temperature will also rise. At this time, the load should be reduced immediately, and the unbalance degree of the three-phase load reduced by the system should be adjusted to make the rotor temperature fall to the allowable range.

(2)转子温度和进风温度正常，而定子温度异常升高，可能是定子温度表失灵。测量定子温度用的电阻式测温元件的电阻值有时会在运行中逐步增大，甚至开路，这时就会出现某一点温度突然上升的现象。

(2) The rotor temperature and inlet air temperature are normal, but the stator temperature increases abnormally, which may be the stator thermometer failure. The resistance value of the resistance type temperature measuring element used to measure the stator temperature will increase gradually in operation, or even open circuit. At this time, the temperature suddenly rises at a certain point.

(3)当进风温度和定子、转子温度都升高，就可以判定是冷却水系统发生了故障，这时应立即检查空气冷却器是否断水或水压太低。

(3) When the inlet air temperature and the temperature of stator and rotor increase, it can be judged that the cooling water system is in fault. At this time, it is necessary to check whether the air cooler has water cut-off or the water pressure is too low.

(4)当进风温度正常而出风温度异常升高，这就表明通风系统失灵，这时必须停机进行检查。有些发电机组通风道内装有导流挡板，如因操作不当就会使风路受阻，这时应检查挡板的位置并纠正之。

(4) When the inlet air temperature is normal and the outlet air temperature is abnormally high, it indicates that the ventilation system is out of order. At this time, the machine must be shut down for inspection. Some generating units are equipped with deflector in the ventilation duct. If the air passage is blocked due to improper operation, the position of the baffle should be checked and corrected.