Configuration and use of UPS power in DCS control system
The UPS is an uninterruptible power supply, which is a system device that connects a battery (mostly a lead-acid maintenance-free battery) to a host computer and converts the direct current into a commercial power through a module circuit such as a host inverter. It is mainly used to provide stable and uninterrupted power supply to a single computer, computer network system or other power electronic equipment such as solenoid valves, pressure transmitters, etc. When the mains input is normal, the UPS will supply the mains to the load for use. The UPS is an AC-type voltage regulator, and it also charges the battery inside the unit; when the mains is interrupted (accident blackout) At the same time, the UPS immediately supplies the 220V AC power to the load through the inverter switching method, so that the load maintains normal operation and protects the load from soft and hardware. UPS devices typically provide protection against excessive voltage or low voltage. UPS is aimed at the reliability requirements of power grids in China's power grid environment and network monitoring and network systems, medical systems, etc., to overcome the problem of the increasingly harsh power supply grid environment caused by centralized power supply of medium and large computer network systems, and developed with new digital technology. The third generation of power frequency pure online intelligent UPS. The DC power supply is a device that maintains a constant current in the circuit. Such as dry batteries, batteries, DC generators, etc. UPS and DC power supply are important power supply protection equipments for enterprises. Traditional maintenance management includes: 1 daily inspection appearance, regular replacement of batteries, filter capacitors, fans and other wearing parts, battery activation during overhaul; 2 transformation or replacement equipment Use advanced tools to test battery performance. This kind of management method has high input cost and large workload for maintenance personnel. It is not easy to grasp the running status and key data of the equipment in real time, and the equipment accident prevention ability is low. Implementing online maintenance management can avoid the shortcomings of the traditional methods and achieve good benefits. UPS Chinese means "uninterruptible power supply", which is the abbreviation of "UninterrupTIble Power System/UninterrupTIble Power Supply" in English. It can guarantee that the computer system will continue to work for a period of time after the power failure, so that the user can save the disk urgently, so that the user does not suffer from power failure. Affect work or lose data. DCS control system The distributed control system is a new-generation instrument control system based on microprocessors, which adopts the control principle of decentralized control functions, centralized display operation, and autonomous and comprehensive coordination design principles. The distributed control system, referred to as DCS, can also be literally translated as "distributed control system" or "distributed computer control system." It adopts the basic design idea of ​​controlling the decentralization, operation and management concentration, and adopts the structure of multi-level hierarchical and cooperative autonomy. Its main feature is its centralized management and decentralized control. At present, DCS has been widely used in various industries such as power, metallurgy and petrochemical. DCS usually adopts hierarchical hierarchical structure, as shown in Figure 3.1. Each level consists of several subsystems, each of which implements certain specific finite targets to form a pyramid structure. Reliability is the life of DCS development. There are three main measures to ensure the high reliability of DCS: one is the extensive application of high-reliability hardware equipment and production technology; the second is the extensive use of redundancy technology; the third is widely implemented in software design. System fault tolerance technology, fault self-diagnosis and automatic processing technology. Most of today's distributed control systems have MTBFs of tens of thousands or even hundreds of thousands of hours. The working principle of the UPS system: the factory power supply with poor power supply quality is first converted into a DC power supply by a rectifying device, one is charged by the charging module to the battery, and the other is re-inverted by the high frequency pulse width modulation (SPWM) method. Turn the DC power supply into a pure, high quality sine wave power supply to power the load. When the AC working power supply disappears or components such as the rectifier device fail, the battery pack supplies power to the inverter device via the battery switch. When the inverter output voltage is abnormal or overloaded, the automatic bypass switch is switched from the factory power supply to the load directly. The plant has fewer input and output points for the DCS system, and adopts dual AC incoming line single UPS power supply mode. The DCS system has many input and output points, and adopts dual AC incoming line and double UPS parallel power supply mode. 1 double AC incoming line single UPS wiring Double AC incoming line single UPS power supply wiring is shown in Figure 1: In the normal case, the AC input 1 supplies power to the UPS, when AC input 1 In the event of a fault, it automatically switches to AC input 2 to supply power to the UPS, and AC power supplies 1 and 2 perform circuit interlocking. When the UPS is in normal working condition, it works according to the operation mode of “AC input 1—rectification-inverter-loadâ€; when the rectifier module is faulty, it works according to the “battery-inverter-load†operation mode; when the battery is discharged Automatically switch to the AC power supply directly from the automatic bypass switch; when the inverter module is faulty, press the "AC input 1 - automatic bypass switch - load" mode of operation to directly supply power to the load; when the UPS has When a serious fault needs to be repaired or replaced, press the “AC Input 1—Manual Maintenance Bypass Switch†mode to supply power to the load. At this time, the UPS is shorted and can be overhauled or replaced without affecting the load. Normal power supply. 2 dual AC incoming line dual UPS parallel power supply mode Therefore, it is required that the output voltages of the two UPSs in parallel are the same, the frequencies are the same, the phases are the same, and the load currents are basically balanced. When the dual UPS parallel system is in normal operation, the two UPSs each have a load current of 1/2. If one UPS fails, the other will carry all the load, but the load must be reduced. The average time between failures of this parallel dual UPS system is 7-8 times that of a single system, which greatly improves the reliability of the system. However, there is a certain relationship between the control of the two UPSs of the dual UPS parallel system. The operation logic must be clarified and the control logic of the board will be incorrect. Otherwise, the output voltage will be sag due to misoperation of the parallel board. The load caused an adverse effect. 3 UPS use precautions (1) UPS should leave a certain margin in the selection, such as 4KVA load, UPS should be configured more than 5KVA. (2) UPS should avoid frequent opening and stopping, preferably in the long-time state. (3) The newly purchased UPS should be charged and discharged, which is beneficial to prolong the service life of the UPS battery. Generally, constant voltage charging is adopted, and the initial charging current should not exceed 0.5*C5 amps (C5 can be calculated by the rated capacity of the battery), and the voltage of each battery is controlled at 2.30~2.35V to avoid damage to the battery. The charging current is unchanged for 3 hours, which proves that the battery is sufficient. The charging time is generally 12 to 24 hours. (4) If the power consumption of the factory has been normal, the UPS will not have a chance to work. The battery may be damaged in the long-term floating state. The UPS should be charged and discharged periodically, so that not only can the battery be activated, but also whether the UPS is working properly. status. (5) Regularly check the UPS and check the float voltage every month. If the float voltage is lower than 2.2V, the entire battery should be balanced. (6) Always wipe the battery with a soft cloth to keep the battery surface clean. Double AC incoming line dual UPS parallel power supply mode as shown in 2: by directly connecting the output of two UPSs with the same power (7) temperature control during UPS operation, because the temperature range control during UPS operation In the range of 20 ° C ~ 25 ° C, to extend the life of the UPS battery. In environments where there is no air conditioning, temperature control of the UPS is especially important. (8) The UPS should be charged immediately after use to restore the battery to a normal state. (9) The distance from the external battery pack to the UPS should be as short as possible. The cross-sectional area of ​​the wire should be as large as possible to increase the conductivity of the wire and reduce the power loss on the line. Especially when working at high current, the loss on the line can not be ignored. . 4 UPS daily maintenance and general troubleshooting 4.1 Routine maintenance (1) Check the UPS operation display every day to confirm whether the UPS power supply running status analog indicator is in normal operation. (2) Use the ear to hear whether the UPS power supply has abnormal noise, mainly the cooling module of the power module and the isolated output transformer, and whether the transformer has abnormal vibration sound. (3) Check the air outlet of the UPS power supply for blockage. (4) Check the floating voltage of the battery, the output voltage and current of the UPS every week on the display of the UPS power supply, and make a record. Compare with the previous data. If the data changes relatively large, you should find out the cause in time. 4.2 General Troubleshooting When the UPS power supply has an alarm during operation, do not panicly operate any switches or buttons of the UPS to avoid expanding the accident or even causing the UPS output to be interrupted. When the UPS power supply alarm occurs, you should first see the status indicator on the display panel and the LCD display prompt. The UPS has a self-diagnostic function. When a fault occurs, it will provide information such as the fault type and fault time through the status indicator and the LCD. After the status indicator and the LCD display provide the fault type prompt, perform corresponding processing according to different fault types. During the operation of the UPS, the following types of faults often occur. (1) The power failure of the AC power plant, that is, the AC input power failure or a wide range of fluctuations. When the alarm occurs on the UPS, the battery discharge alarm message appears at the same time. At this time, the AC input light of the UPS panel status indicator is off, and the battery discharge light is on. . The first method to determine whether to communicate the power failure of the plant, check whether the UPS input switch is tripped, and whether the fuse is blown. If it is a factory power failure, the unimportant load is removed without knowing the recovery time to ensure uninterrupted power supply of important loads. (2) Inverter fault, when the alarm occurs, the automatic bypass switch is loaded with the alarm. First, confirm whether the inverter overload alarm appears on the panel at the same time. If yes, check the output current on the LCD screen. When the rated current is exceeded, the unimportant load is turned off until the output current is less than the rated output current, and then the reset button is pressed to cancel the alarm, and the inverter is restarted and output. If there is no overload warning signal, it means that the inverter is not closed due to the inrush current, but the IGBT device or the drive control is faulty, and the manufacturer should be notified in time for maintenance. (3) Bypass failure, when the alarm signal appears, the inverter asynchronous alarm signal should generally appear at the same time. This indicates that the input plant power voltage and frequency are outside the set range, but meet the rectifier requirements. At this time, the inverter self-oscillates and no longer bypasses the bypass. At this time, the large-capacity load cannot be started again to avoid impacting the inverter. 5 Conclusion As long as the UPS power supply is configured properly, daily maintenance and maintenance should be taken to prevent the UPS from running stably and reliably, and the DCS system can be safely, reliably and with high quality to ensure safe, stable and long-term chemical production. Run periodically. KW4-Lever Type Of Micro Switch Micro Switch with Lever,Lever Micro Switch,Microswitch Lever in Industrial Microswitches Ningbo Jialin Electronics Co.,Ltd , https://www.donghai-switch.com
