1. Generator non synchronous parallel

發電機用準同期法并列時，應滿足電壓、頻率、相位相同這3個條件，造成并車失敗,如果由于操作不當或其它原因，并列時沒有滿足這3個條件，發電機就會非同期并列，它可能使發電機損壞，并對系統造成強烈的沖擊，因此應注意防止此類故障的發生。 當待并發電機與系統的電壓不相同，其間存有電壓差，在并列時就會產生一定的沖擊電流。

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.

一般當電壓相差在±10%以內時，沖擊電流不太大，對發電機也沒有什么危險。如果并列時電壓相差較多，特別是大容量電機并列時，如果其電壓遠低于系統電壓，那么在并列時除了產生很大的電流沖擊外，還會使系統電壓下降，可能使事故擴大。一般在并列時，應使待并發電機的電壓稍高于系統電壓。

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.

如果待并發電機電壓與系統電壓的相位不同，并列時引起的沖擊電流將產生同期力矩，使待并發電機立刻牽入同步。如果相位差在±300以內時，產生的沖擊電流和同期力矩不會造成嚴重影響。如果相位差很大時，沖擊電流和同期力矩將很大，可能達到三相短路電流的2倍，它將使定子線棒和轉軸受到一個很大的沖擊應力，可能造成定子端部繞組嚴重變形，聯軸器螺栓被剪斷等嚴重后果。 為防止非同期并列，有些廠在手動準同期裝置中加裝了電壓差檢查裝置和相角閉鎖裝置，以保證在并列時電差、相角差不超過允許值。

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、發電機溫度升高

2. Generator temperature rise

(1)定子線圈溫度和進風溫度正常，長期過載,局部線卷有短路,通風不暢,而轉子溫度異常升高，這時可能是轉子溫度表失靈，應作檢查。發電機三相負荷不平衡超過允許值時，也會使轉子溫度升高，此時應立即降低負荷，并設法調整系統已減少三相負荷的不平衡度，使轉子溫度降到允許范圍之內。

(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)轉子溫度和進風溫度正常，而定子溫度異常升高，可能是定子溫度表失靈。測量定子溫度用的電阻式測溫元件的電阻值有時會在運行中逐步增大，甚至開路，這時就會出現某一點溫度突然上升的現象。

(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)當進風溫度和定子、轉子溫度都升高，就可以判定是冷卻水系統發生了故障，這時應立即檢查空氣冷卻器是否斷水或水壓太低。

(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)當進風溫度正常而出風溫度異常升高，這就表明通風系統失靈，這時必須停機進行檢查。有些發電機組通風道內裝有導流擋板，如因操作不當就會使風路受阻，這時應檢查擋板的位置并糾正之。

(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.