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 水泵跳闸毛病的掃除辦法

date.png 2020-04-02 15:54:16

水泵跳闸毛病的掃除辦法   1.毛病现象:某電廠125 mw機组自投產以來,给水泵偶然會發作一閤闸即跳闸的问题,并無信號繼電器掉牌。在掃除瞭開關機構毛病後,葫蘆岛水泵廠按常规辦法检查電缆、二次迴路接线和各繼電器及其定值都正常,再次啟動又常常勝利。後疑心是dcs係统软毛病形成的,但改在控製盤上操作,仍會呈现此现象。   2.實验查找缘由:爲查清此现象的缘由,察看開關閤闸過程中各錶计的變化狀况,以確認是何缘由使水泵跳闸。實验其中電壓錶監视微機跳闸迴路,毫安錶監视差動繼電器1cj、2cj動作狀况,電流錶監视熱工维護迴路。接好錶计後,啟動给水泵,经過一段時间的實验,终于有一次一啟動就水泵跳闸,同時察看到毫安錶的指针偏转瞭一下,其牠監视錶计没有反響,新换上的xjl-0025/31型集成塊式信號繼電器1xj亦動作掉牌,標明是由差動维護動作招緻水泵跳闸。  3.本源剖析:差動维護動作,首先疑心被维護设備内部有毛病。经過常规检查,给水泵電機及其電缆正常,差動繼電器校验正常,電流互感器極性衔接正確。在掃除设備毛病和接线错误的缘由後,差動维護在電機啟動過程中動作,葫蘆岛水泵廠標明在這過程中差動迴路的差電流超越差動繼電器整定值。正常狀况下惹起差動迴路差電流的缘由主要有兩點。一是電機首尾兩侧的電流互感器變比误差不同,存在一個很小的差電流,這個差電流小于電機额定電流id的5%。二是首尾兩侧電流互感器二次负荷的差異也會惹起其變比的差異,從而存在一個差電流。在给水泵電機差動维護迴路中的電流互感器负荷差異隻是二次電缆長度的不同,大约相差50m,并且在额定電流下,差動繼電器的功率耗费不大于3va,二次负载并不重。检查發现给水泵電機差動维護用的首尾侧電流互感器型號均爲lmzbj-10,b级15倍额定電流,變比600/5,容量40va,完整能满足二次负载的请求。

1. Fault phenomenon: since the 125 MW unit of a power plant was put into operation, the feed pump occasionally trips when it is closed, and there is no signal relay dropping. After clearing the fault of the switch mechanism, Huludao water pump plant checks the cable, secondary circuit wiring, all relays and their settings are normal according to the conventional method, and it is often successful to start again. The latter suspicion is caused by the soft fault of DCS system, but it will still appear if the operation is changed on the control panel.


2. Experiment to find out the reason: in order to find out the reason of this phenomenon, check the changes of meters in the process of switch closing to confirm why the water pump trips. In the experiment, the voltmeter monitors the trip circuit of the microcomputer, the milliammeter monitors the action of the differential relay 1cj and 2cj, and the ammeter monitors the thermal maintenance circuit. After connecting the meter, start the feed water pump. After a period of experiment, the water pump trips at one start. At the same time, it is observed that the pointer of the milliammeter deflects for a while, and there is no response from other monitoring meters. The new xjl-0025 / 31 integrated block type signal relay 1xj also acts as a drop board, indicating that the differential maintenance action causes the water pump to trip.


3. Source analysis: for differential maintenance action, first suspect that there is something wrong inside the maintained equipment. After routine inspection, the motor and cable of feed water pump are normal, the differential relay is normal, and the polarity of current transformer is connected correctly. After clearing the causes of equipment faults and wiring errors, the differential maintenance operates during the motor startup process. Huludao water pump plant indicates that the differential current of the differential circuit exceeds the setting value of the differential relay in this process. There are two main reasons for causing differential current in differential circuit under normal condition. First, the ratio error of current transformer on both sides of motor head and tail is different, there is a very small difference current, which is less than 5% of rated current ID of motor. Second, the difference of the secondary load of the current transformer on both sides of the head and tail will also cause the difference of its transformation ratio, so there is a difference current. The load difference of current transformer in the differential maintenance circuit of feed water pump motor is only the difference of secondary cable length, about 50m. Moreover, under the rated current, the power consumption of differential relay is not more than 3VA, and the secondary load is not heavy. Through inspection, it is found that the model of current transformer at the head and tail side for differential maintenance of feed pump motor is lmzbj-10, class B 15 times of rated current, transformation ratio is 600 / 5, capacity is 40VA, which can completely meet the requirements of secondary load.


联系方式

ico04
联系人

徐经理

ico01
电话

0312-3426976

ico06
手机

13932271419

ico05
QQ

632469545

ico03
邮箱

632469545@qq.com

ico02
地址

河北安国市石佛镇路景工业园区景旺路8号

 
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