The selection and use of small pumps: First, select the standard pump 1, what is the standard pump Standard pump is the country according to the requirements of ISO, development, implementation of the latest models of pumps. Its main features are small size, light weight, excellent performance, easy operation, long life, low energy consumption. It represents the latest trend of the current pump industry. 2, how to choose the pump When the user selects the pump, it is best to agricultural machinery department approved point of sale, we must recognize the manufacturer. It is recommended to give priority to the purchase of water-filled submersible pumps, and to see the grades and product quality certification. Do not buy "three no" (that is, no manufacturer, no production date, no production license) products, otherwise there is a problem, the user will do nothing. 3, what brand of pump as a good user, due to the limitations of professional knowledge, it is difficult to decide, the best way is to consult the pump experts. If you really no one consulting, may wish to consult some of the older pump users, especially those who are close to their own conditions, to buy these users reliable, reliable and more mature products, after all, a wise choice. At the same time, should be based on local power supply situation to decide with single-phase pump or three-phase pump. Second, choose to meet the lift requirements of the pump 1, pump lift choice The so-called lift is the required lift, rather than lift height, it is clear that the selection of pumps is particularly important. Pump lift about 1.15 to 1.20 times the height of the lift. If a water source to the water vertical height of 20 meters, its required lift is about 23 to 24 meters. Select the pump should make the best lift on the pump nameplate and the required head close, in this case, the highest efficiency of the pump, the use of more economical. However, it is not absolutely necessary that the pump should be absolutely energy-efficient. As long as the average deviation does not exceed 20%, the pump can work under more energy-efficient conditions. 2, how much the nameplate head is better Select a pump on the nameplate lift is much smaller than the desired lift, often can not meet the user's wishes, even if it can pump water, the water will be pitiful, or even become useless Wu land of "free pump." Whether to buy the pump lift the higher the better? actually not. High-lift pump for low lift, there will be excessive flow, resulting in motor overload, if the long run, the motor temperature, the winding insulation will gradually aging, or even burn the motor. Third, select the appropriate flow pump pump flow, that is, the amount of water generally not too large election, otherwise, will increase the cost of purchasing a pump. Specific issues should be specific analysis, such as users own draft self-priming pump, the flow should be selected smaller; such as user irrigation submersible pump, you can choose the appropriate flow larger. Fourth, the use of several issues should pay attention to correctly grasp the use of the pump is to extend the life and reduce economic losses an important factor. 1, for the submersible sewage pump should start to do some necessary checks before starting: the pump shaft rotation is normal, with or without stuck phenomenon; impeller position is normal; cable and cable plug without rupture, abrasions and broken phenomenon . Operation should pay attention to observe the voltage changes, the general control of the rated voltage within ± 5%. In addition, the location of the submersible sewage pump in the water is very important, should be selected as much as possible in the water, non-silt, good water quality, vertical hanging in the water, not allowed to horizontal, so as not to fall into the mud or suspended solids blocked pump inlet , Resulting in a sharp drop in water or even pumping to the water. 2, for the self-priming pump should be placed in a well-ventilated place to run, in order to facilitate rapid cooling, reduce the motor temperature. Otherwise, prolonged operation, easy to burn the motor. If a farmer is using a self-priming pump, the motor is overheated and the coil burned out because the plastic film covering the motor is not removed. In addition, before starting, be sure to check the pump body of water, otherwise, not only affect the self-priming performance, but also easy to burn shaft seal components. Under normal circumstances, the pump should start 3 to 5 minutes after the water, or should immediately stop checking. 3, pump maintenance When the pump fails, should not disassemble yourself. Because of their demolition, I do not know where the fault is caused by blindly dismantling a pass; Second, there is no special tools and often damage the original parts intact. The best way is to have the experience, the maintenance of scale maintenance, and timely replacement of "over age" parts and some wearing parts. Under normal circumstances, the pump should be repaired once every six months, to eliminate "sick" work. 4, non-use period stored in non-use period, the pump should be promptly removed from the water, and empty the pump water, especially in the cold winter. Then place it in a dry place, conditional users can also apply butter in the key parts of the pump, add lubricant to the bearings to prevent corrosion of parts. In addition, the non-use of the pump, not the longer the better. If you do not use for a long time, not only easy to rust parts, but also reduce the service life of the pump. Pump Trip Troubleshooting 1: Symptom A power plant 125 mw unit has been in operation since its production, the pump occasionally a closing or tripping problem, and no signal relay card out. After excluding the switchgear failure, according to the conventional method of checking the cable, the secondary circuit wiring and the relay and its rating are normal, start again often successful. Dcs system after the suspicion of soft failure caused, but the change in the control panel operation, there will still be this phenomenon. 2: The reason for the test to find out the reasons for this phenomenon, observe the changes in the process of closing the switch to confirm what is the reason for tripping. Test voltage meter which monitors the microcomputer trip circuit, mA watch differential relay 1cj, 2cj action, ammeter monitoring thermal protection circuit. Pick up the meter, start the pump, after a period of testing, and finally once the pump started that trip, while observing the mA ammeter deflection of the watch a bit, the other watch does not respond, the new xjl-0025 / 31 integrated block signal relay 1xj also action card, that is caused by the differential protection action trip. 3: Root Cause Analysis of differential protection, first of all suspected to be protected equipment within the fault. Through routine inspection, the pump motor and its cables are normal, the differential relay is calibrated, and the polarity of the current transformer is connected correctly. After eliminating the causes of equipment failure and wiring errors, differential protection operates during motor start-up, indicating that the differential current of the differential circuit exceeded the differential relay setting during this process. Under normal circumstances, the differential current caused by differential current loop there are two main reasons: First, both sides of the motor current transformer ratio error is different, there is a small difference current, the difference current is less than 5% of the motor rated current id . Second, both ends of the current transformer secondary load difference will cause the difference between the ratio, so there is a difference current. The difference in current transformer load in the feed pump motor differential protection circuit is only a difference of the secondary cable length of about 50 m, and the power consumption of the differential relay is not more than 3 va at rated current and the secondary load is not weight. Check found that the pump motor differential protection with tail-end current transformer models are lmzbj-10, b-level 15 times the rated current, the ratio of 600/5, the capacity of 40 va, fully meet the secondary load requirements. The above analysis is based on the normal operation of the condition, the motor starts, the situation is different. When the motor starts, the current is very large. The current transformer on both sides of the motor may be saturated. In this case, the secondary differential current may be very large due to the inconsistent magnetization characteristics of the current transformers. According to Acheng Relay Factory lcd-12 differential relay setting instructions, the relay operating current setting izd = △ i1 × kk × in / n = 0.06 × 3 × 356/120 = 0.534a Where: △ i1-first , The maximum error of the tail current transformer during normal operation, 0.04 ~ 0.06; kk-reliability coefficient, 2 ~ 3; in- motor rated current; n- current transformer ratio. Should be set at 1.0a position. The use of b-level transformer case, the differential relay operating current set at 1.5a, the braking factor of 0.4, the differential protection is still occasionally activated when the motor starts, is due to b-level current transformer magnetization saturation point Lower, anti-saturation capacity is low, can not meet the requirements of the differential relay. Usually require differential protection circuit current transformer using d-level, d-level transformer saturation point higher, not so easy to saturation, can reduce the difference between the current flowing through the differential loop when the motor starts. In the replacement of the d-level current transformer, while the differential relay operating current set at 1.0a, the braking factor of 0.4, no longer appeared to switch a switch that trip. Centrifugal pump use and maintenance Centrifugal pump as a rotating material conveying equipment, the production of chemical plant, especially for the more continuous chemical production is particularly important. Because of the uneven level of equipment management of each manufacturer, the use of centrifugal pumps are also different. How to improve the utilization rate of centrifugal pumps and improve their service life has always plagued the enterprise equipment management major issue.
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