Contents
HOW TO DETECT ELECTRICAL FAULTS IN CEMENT PLANT
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Continuity modern dry process cement production line process of strong, stable production processes requires major, coordinated and efficient, so the safe operation of electrical equipment also made considerable demands. In addition, cement production enterprises is a high energy-consuming enterprises, motor types, large capacity, high voltage level, wide distribution, high degree of automation, so that the maintenance of electrical equipment difficult. Many maintenance personnel face complex electrical control circuit devices, often unable to start, the high voltage level, the capacity of the device did not dare to do it. Many electrical workers engaged in practical work have this experience. Range of electrical failure is very broad, ever-changing phenomenon, strong randomness, it is difficult to find. This article will talk about a few cement plant electrical troubleshooting experience for reference.
1Find a power failure
For complex electrical failure, electrical failure to find the root cause investigation should start from in order to solve the problem. Some power failure often have their own characteristics.
1.1Overall power failure is a failure of the electrical device
Whether it is a circuit failure, or equipment failure, failure in terms of range, all belong to localized failure, the impact is relatively small, and the power circuits and devices are Work”source”,”source”Out of the question, it will make the whole circuit and devices are not working properly. Thus, the integrity of a power failure fault belongs.
In the electrical fault, most obviously dangerous faults, such as circuit breaker, the device can not work; short-circuit, short-circuit current effect is obvious. However, some power failure is not obvious, or that it is hard to find fault range from its manifestations. For example, the AC waveform does not meet the requirements, electrical equipment heat can increase, decrease motor speed and the like, but the dangers of the failure can not be ignored.
1.3Smaller causal factors of power failure
Most of the power failure is not an accident occur once or twice, it might appear from the start of operation of the equipment. Because of this small, it provides a way for us to find an electrical fault. If some electrical failures long-standing phenomenon, power aspect should be taken into account.
2Find equipment and components of electrical failure
Equipment and elements constituting the core part of the electrical device, its basic function is to send, receive, process, conversion is performed, or output power of the electric signal. Electrical failure occurs mainly in terms of equipment and components. Therefore, look for equipment and components of electrical failure is the most important content.
Electrical equipment and cement component type variety, such as various motors, servo actuators, the contactor control circuit, various temperature relay, the automatic control system, pressure, level, the load cell, and cement industry special equipment, such as high temperature camera, color pyrometer, gas analyzers, etc., are all areas of electrical devices and components. Its structure, properties, categories, features, etc. vary widely, we are actually very difficult to find some kind of fixed pattern to find fault where, the following classification will be introduced.
2.1Automation and control
2.1.1introduction
Using a cement plantDCSSystem software and hardware configuration powerful, user-friendly and feature-rich hardware interface board, flexibility, reliability, and cost is very high. The control requirements, the distribution station control room installation site, all instruments production site signals are sent to each control station belongs, byI/OInterface card handling evacuationDCSProcessing and control according to the control strategy.
Each control station receives and emits signals substantially divided into two categories: digital(switch)signal(DI,DO)And analog signals(AIAO). Digital signals include: on-site eachMCCSuch as control cabinet”Central to select, ready, operational feedback, fault, limit, speed(There deviation and rope belt), The actuator limit torque, damper position, various alarm detectors, each temperature field switches, pressure switches,’Level switch”And the like; analog signals(GenerallyO~10 Vor4~20 mA)Comprising: speed, temperature, pressure, flow, level, level, stroke, opening of the shutter actuator, the gas content of the gas analyzer, various kinds of scale(Belt scales, rotor scale, roller scale, silo, weighbridge)It said weight, volume of feed the same amount.
2.1.2Finding fault
For the production of the cement industry, in some cases inevitably be affected by environmental factors dust, vibration, high temperature, and by the various types of multi-site signal contacts, relays, speed, use of various types of switches, each of the measuring instrument instruments, etc. produced, they work long hours it is inevitable problems in poor working conditions, when failure should focus on two aspects lookup.
2.1.2.1Find digital signal failure
First, check the power supply, control power is normal; The comprehensive analysis of the failure information and failure phenomena provided in the control room, the device checks start and stop condition focus and soft and hard chain condition is provided; the control cabinet element contact device, contact points of the contact is in good condition, the control logic circuit is intact, the wiring is loose; within the site controllerI/OTerminal wiring is loose, a control signal is issued, the insurance signal is blown; the case of a pressure, flow or temperature switch, also check to verify whether the value of the real field operation request; smart field devices, or if the instrument, check whether there is need to place fault, alarm information, the parameter setting is correct; if the field device fault cause can not be started, whether the operation of the protection device. I believe that in-depth understanding of device control theory based on the combination of experience and based on the above principles, digital signal failures are easier to find.
2.1.2.2Find the analog signal failure
(1)The reaction is inaccurate signals, such as temperature, to check the thermal resistance, the thermocouple insertion depth position, whether the surface crust, wiring is loose, rust and the like; if the pressure, flow rate signals, but also check whether the survey line blockage , leakage, position of the valves, the transmitter is good and the like; case weight, speed, level and other signals, to check the sensor is good, the wiring is correctly tightened, the settings are correct and the like; if the parameter is an electrical signal, check the voltage, current transformer, the transmitter is normal; at the same time due to the environmental impact and electromagnetic interference, inevitably there are various types of field instruments, large or small drift, which requires periodic calibration, tuning, or compensation adjustments, and to a blocker.
(2)The reaction for errors, faults, no indication signal, to check the focus of the field power supply terminal, cable or line is disconnected, the measuring device is intact, the parameters are set correctly, the question whether the over-range actually present, various types of sensors is damaged and many more.
Since the analog signal with respect to the digital signal, the detection and processing complex, relatively complicated apparatus, and anti-interference ability, are more susceptible to a direct impact on the work environment, and therefore more difficult to handle. But with the development of electronic technology, field instrumentation continuously improve performance, more powerful, and more now live instrumentation with digital and intelligent, with a self-diagnostic function, making the repair and maintenance becomes easy and fast.
2.2Site electrical equipment aspects
Site electrical equipment up to the number of asynchronous motor applications, the most widely distributed, so I will only talk about a few experiences asynchronous motor fault finding.
2.2.1Find the asynchronous motor failure caused by external equipment failure
External device type asynchronous motor range, they are likely to cause damage to the failure of the motor itself. For example, load fault may cause difficulty in starting the motor running overload, heat, vibration, even when serious burn motor. Due to large amount of cement dust, electrical contact failure is the largest weekdays amount of maintenance, and is one of the hardest to find fault. The main contact”Virtual access”，