Introduction of industrial UPS for environmental application in cement industry

Abstract: The cement production process is complex, the equipment is interlocked, and various detection signals affect each other. If traditional manual control or relay instrument control is used, it is difficult to meet the control requirements. If any of the equipment on the production line fails due to electrical failure, it will affect the operation of the entire production line. In severe cases, material pressing and blockage will occur, which will cause great losses to production. Therefore, most of the new dry-process cement plants use distributed computer control systems for control (DCS) to control and monitor the cement production line in real time. Once these equipment malfunctions, goes down, or even causes data loss due to power problems (power outages, surges, overvoltages, low voltages, etc.), it will cause major accidents, threaten grid security, and cause inestimable losses. Most motors are controlled by starting control equipment such as AC contactors, soft starters and frequency converters. The AC contactor will be released when the power is sloshing, and the soft starter and the inverter will also stop. Therefore, many important low-voltage motors are often stopped due to the sloshing in the industrial production.


Keywords: industrial UPS in cement industry, avoid voltage sag or rise, voltage surge, harmony interference, frequency drift, transient high voltage, power quality issues such as power off in city grid. Protection of sensitive load such asFCS、DCS、PLC、various motor inverters.  


We all know no matter how much it takes to improve power grid, these situations can’t be avoided as voltage sag or rise,harmony interference, frequency drift, transient high voltage,power quality issues such as power off in city grid, which has bad effects on users. Due to amounts of load in power grid, whose operation status, failure situation and natural disasters can affect safety and reliability, such as lighting and rainstorm, wind andhigh wind and snow, building construction, crane, excavator personnel misoperation, animal contact, start of other large motors, short circuit failure, failure of line switching power distribution device, etc


The cement production process is complex, the equipment is interlocked, and various detection signals affect each other. If traditional manual control or relay instrument control is used, it is difficult to meet the control requirements.

If any of the equipment on the production line fails due to electrical failure, it will affect the operation of the entire production line. In severe cases, material pressing and blockage will occur, which will cause great losses to production.

Development of cement plant control system, 1, Pneumatic instrument control system; 2 Electric combined analog instrument control system;3 integrated data control system; 4 distributed control system;5 fieldbus control system.


once these equipment malfunctions, goes down, or even causes data loss due to power problems (power outages, surges, overvoltages, low voltages, etc.), it will cause major accidents, threaten grid security, and cause inestimable losses.


These equipment desperately need pure AC power with high reliability and safety, while UPS could solve above problems, which will provide uninterruptable power for important equipment such as computer, producing control system and so on. It will guarantee equipment free of dangerous as malfunction, goes down and data loss by providing pure UPS when any accidents happen to power grid.


The new dry production line of cement consists of raw material preparation system, raw material homogenization system, kiln tail firing system, kiln head firing system and finished product packaging system. f raw material preparation system consists of grinding of raw materials and raw materials, which is used to make qualified raw materials. Grinding of raw materials isent to the raw meal homogenizing warehouse by the hoist through the air conveying chute at the top of the warehouse.The raw material from the homogenization storehouse is conveyed into the cyclone preheater by a pneumatic lift pump. The material is fully preheated by the negative pressure of the five-stage preheater and then enters the rotary kiln for calcination. The kiln head firing system consists of a feeding system and a clinker generation system. Raw coal is pulverized by coal grinding and stored in the pulverized coal warehouse, and the mixture of pulverized coal and air is fed to the kiln head by a coal fan and a net fan through a flow meter.The raw material after calcination and chemical reaction forms spherical clinker at the kiln head


The spherical clinker enters the single-cylinder cooler through the kiln head cover,after being cooled, then sent to the clinker mill by a chain conveyor for grinding. Finally, the finished product packaging system packs different types of cement in the bulk warehouse into finished products through a packaging machine. The main equipment of the system includes: screw feeder, various fans, humidification tower, kiln main motor, various regulating valves and inverters


1,Concept of Voltage Sag

 Voltage Sag refers to an accident when effective value of power supply voltage suddenly decline substantially and then back to normal. Voltage sag also is called voltage dip and transient voltage fluctuations. Most of voltage sag are caused by lighting, short circuit and starting of heavy load, power supply voltage sag sharply or the voltage is interrupted for a few seconds, which would lead to electrical equipment stop working. Three features are used to describe voltage sag, which is amplitude of transient dip, duration and frequency of occurrence, sometimes sudden change of phases should be considered. The voltage sag is defined by IEEE that the effective value of the supply voltage drops rapidly to 90% ~ 10% of the rated value, and then rises to near the normal value, while IEC defines it as supply voltage drops rapidly to 90% ~ 1% of the rated value whose duration is 10ms~1min.


2, Disadvantages of voltage sag

Most motors are controlled by starting control equipment such as AC contactors, soft starters and frequency converters.The AC contactor will be released when the voltage is fluctuating, and the soft starter and the inverter will also stop.Therefore, many important low-voltage motors are often stopped due to voltage sag in the industrial production, and the shutdown of key units will cause large units or even the entire production unit to be shut down, eventually leading to the interruption of the continuous production process and emergency shutdown of the production unit, which will cause huge economic losses to the enterprise, and sometimes cause fire, vicious accidents such as explosions.


Differences between industrial UPS in cement industry and commercial UPS:

Items

Commercial UPS

Industrial UPS

application environment

The environment is comfortable in IDC machine room or workplace,small temperature change (20-25ºC), moderate humidity, no dust and salt fog.

The environment is horrible in power distribution room, production site and field, big temperature change(-25~55ºC) , high humidity, lots of dust and salt fog.

reliability

Low reliability, design life is about 5 years.

high reliability, industrial or military components are selected, increase redundancy, strengthen craft design and improve safety configuration, design life is 20 years.

Electrical environment

sound electrical environment, voltage fluctuation and transient change is rare, low order harmonics and high frequency interference


Poor electrical environment, more voltage fluctuations and flicker, serious low-order harmonics and high-frequency interference

load characteristics


Single load characteristics, mainly IT equipment, including computers,servers,communication equipment, etc.


Various load characteristics, in addition to IT equipment, it also includes industrial power equipment such as motors, inverters, DC drives, etc.


Mechanical strength


Low, usually modular design

High,usually with high-strength cabinet design

Electrical isolation

No isolation


Standard output isolation, optional input isolation

Protective function

simple

Complete and reliable


Communication Interface

RS485 telecommunication

RS485/232telecommunication,relay dry contact

Bypass requirements

none


Parallel bypass configuration, electrical isolation / voltage regulation, wide output voltage range, rotary manual bypass switch 50 types of bypass cabinet configuration

Attachment selection

none

Dozens of accessories to choose freely based on the diversity of industrial needs and the complexity of the application environment

IP protection degree 

IP20

IP21 to IP54+ explosion-proof design

Sheet mental


Do not accept customization


sheet metal thickness and cabinet color can be customized.

 

Three elements of industrial UPS in cement industry:

Ⅰ、High-level immunity, applied in harsh electrical environment, we do not need to worry as its higher reliability.

Immunity includes radiation sensitivity test,power frequency magnetic field radiation sensitivity test,RF field-induced conduction sensitivity, electrical fast transient burst immunity, surge immunity, voltage sag and interruption immunity, powerline induction / contact, static discharge immunity In the IEC62040-2-2005 from EMC standards, UPS is classified into four categories ,which are C1, C2, C3, and C4, that is, residential zone, commercial zone, and light industrial zone, industrial zone, and special customized zone. Only with good reliability design can product quality be improved. The improvement of reliability is mainly concentrated in the research and development stage and before the finalization.


Ⅱ、optional high-level IP protection degree is applied in harsh space environment, which has improved adaptability and we do not need to worry about it .

In the aspect of environment, commercial UPS normally is applied in IDC machine room, and it has strict requirements for temperature humidity, dust and corrosive gas, and it is not be able to be used in harsh environment, while industrial UPS can be used in environment with high temperature, high humidity, multiple dust or salt fog, commercial UPS has accordance requirements for seismic rating.


Ⅲ、Electrical isolation of power frequency transformer, which improves safety.

Electrical isolation of power frequency transformer could regenerate an TN-S system or IT system, Neutral line flexibility could serve better for users, and reduce system risks. On the opposite, commercial UPS is not equipped with the system.



About AVIC-TECH

Avic-Tech (Xiamen)Electric Power Technology Co.,Ltd is a high-tech enterprise specializing in R&D, manufacture, sales and service of high-end power supply. Our flagship products are industrial UPS (1kVA-800kVA), dynamic voltage restorer (10kVA-2000kVA), and lithium battery system, which are widely used in nuclear power, electric power, petroleum and petrochemical, rail transportation, industrial manufacturing and other fields.

Name: Mia ling

Email: lwy@avic-tech.com.cn  

Official site: http://www.avic-tech.com

Tel: +86 592-2999 677




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