For a long time,in the production process of the Petrochemical, Chemical fiber, Pharmaceutical, Steel and other industries , there are some important equipment driven by AC motor. when the power grid is outage (even for milliseconds) and other power failure, power equipment driven by the motor maybe suffer large disturbance or even stopto cause continuous productioninterruption, equipment broken, and result in a large number of substandard and waste products, resulting in serious economic losses.

In these industries, many enterprises have adopted some traditional solutions such as: dual power supply, diesel generators as a backup power supply and UPS as backup power, but there are many shortcomings in the traditional scheme.

Double power supply: dual power have switching time, the double power switchoverfor the short time,frequency converterwill appear undervoltage shutdown or motor tripping, for continuous production equipment can not solve the strong work requirements.

Diesel generator as a backup power supply: diesel generator as backup power supply also has long start-up time and switching time to causethe motor tripping and inverter stopping phenomenon.

UPS power supply: ordinary UPS is constant pressure and constant frequency output, which can not meet the requirements of the motors’ adjusting speed. If the load of UPS is a kind of motor and choosing the backup UPS,when AC power is failure, the motor power supply, the motor makes its speed down quickly even stops under the action of mechanical load resistance.When UPS power supplies, equivalent of motor restarting, its speed is quick,but for some high technological requirements of the equipment it can not meet the technical requirements to cause some defective products. When choosing the online UPS, the starting current of AC motor is usually5 ~ 7 times as many as its rated current.The standard of the overload capacity of UPS:overload capacity is 125%,Class 1 is for 10min, Class 2 for 1min,  Class 3 for30s; overload capacity is 150% for 10s, overload is greater than 150% for 200ms. If you want UPS endures overload capacity of the motor current,you must increase the capacity of UPS. For example:the power of the motor is 11KW , its rated current is 21A, starting current is 105A ~ 147A, if choosing UPS,its power at least is 55KW, that will undoubtedly increase the investment and cause waste.Hower,choosing DC-BANK,it can only need 11KW.

In order to solve these problems, we develope DC-BANK. The product is AC uninterruptible power supply which is specially used for variable output voltage and frequency of the motor load.It isspecial uninterruptible power supply system for low-voltage motor group,and  especially used in the petroleum, chemical industry,chemical fiber ,steel, glass and other  industries with many load and continuousproduction.

Function of the DC-BANK: after  the electrical system of enterprises occurs fault (shaking 

electricity or power cut), it makes sure themotor continuous,stable,and safe operation to avoids accidents for motor output fluctuations or tripping and greatly reduce losses and danger for production from electrical fault.

 

This system is organizational structure based on inverter and EPS. Battery provides other  power, which is about 560VDC and higher than DC power after converter rectifier (types of inverter is different ,DC output voltage is different), to DC ciurcuit of the convert through DC electronic switching. When the AC power supply of the converter is lost or shaking, the DC electronic switch unit supply power for maintaining stable operation to the inverter. According to the capacity of the battery,it can provide different backup time,at the same time,  the control system uses DC/DC power supply to provide a stable 24V power supply.When AC power cuts off ,it can make sure the motor and the system run without interruption

When the AC power supply is normal, this system adopts presentadvancedhigh frequency switching power supply module , automatically charge battery , and has perfect over-voltage ,over-current and other protection measures. The system can realize real-time online monitoring, and uploadthe monitoring datasto user’ computer, to be convenient remote monitoring. At the same time,it output frequency, current signal to the DCS systemthrough the 4-20mA.

Working principle of DC-BANK:

1.The main loop supplies power.When AC power is normal,it drives motor running through the AC power distribution system, inverter VVVF (DC bus voltage is rectified up to about 520 ~ 600V) .  

2.When the city electricity is failure, the DC bus of the inverter is less than 500V, and the battery is input to the DC-BUS of the inverterwithout interruption.That ensures the stability of the motor under the support of the battery.  

3. When the city electricity restores normal, DC-BANK automatically cuts off the battery . In this process, the input voltage, frequency and speed of the motor will not any disturbance.

4. The control system adopts DC/DC power supply to provide stable 24V power supply.When AC power is outages, it ensures that the motor and the system are not interrupted.

 

1. Per set DC-BANKtakes a three-phase 380V AC motor, which is directly connected to the output of EPS power.There is no control circuit before the motor.

2.DC-BANK need to have the function of the frequency conversion starting and adjusting speed regulation .

3.Using on-site operation column can start and stop DC-BANK, monitor current and frequency of the motor, and manually adjust the output voltage and frequency of the DC-BANK .

4.It can start and stop DC-BANK through the DCS , monitor motor current and frequency, and can regulate the output voltage and frequency of the DC-BANK through the 4-20mA signal.

5. AC input of each set of DC-BANKis AC380 ±15%. Normally, the plant supplies with 380 AC power.When AC input power supply cuts out , the battery power will supply power to inverter.

6.The model of the matching inverter model can accept the user's choice.

7. It could systematically select battery inspection instrument to  viewthe voltage of a single battery in real-time.

8. Optional on-site operation column: three anti-operation column ( anti-corrosion,anti-water and anti-dust)，two lights, four buttons, a switch, a ammeter (4~20mA input), a frequencymeter  

( 4~20mAinput).It realizes to check the frequency and current of the motor, and start, stopp and adjust speeding.

9. The system has been put into operation by the user ,which can upgrade uninterruptible power supply system. It can simultaneity support multiple frequency inverter with uninterruptible power supply through DC system. That greatly saves investment, and get less additional loss.

10. In the technological process of non continuous full load, when load is light , through the feedback circuit to control the motor low speed operation,it can achieve energy saving, and reduce production costs.

11. When starting through frequency conversion, that can effectively reduce the impact on the grid, and the interference of the power grid.