Corona treatment is widely used in the industrial field. It can be used for treating flexible packaging, lithium battery, aluminum foil, sheet, tube, wires, foam and etc. It can cooperate with extrusion machine, printing machine, laminating machine, coating machine and etc.

Nantong Sanxin Plastics Equipment Technology Co.,Ltd has started to produce corona treatment since 1992, and the technology ranks top 1 in China. Sanxin is willing to share the common problems and solutions. Here we will take CW3008 as an example.

Description of corona treatment

Corona treatment is consisted of corona generator, transformer and discharge rack. The principle is that the generator rectifies the three phase AC power supply into DC and sends it to the power converter component, and then compose a half bridge inverter circuit. This power supply generates AC medium voltage with a frequency of approximately 20khz, and then generate high frequency and high voltage electricity through transformer to discharge rack.

The discharge rack is a device that contains the relative electrodes which required for high-voltage discharge. The electrode is coated with insulating medium, normally ceramic or silicon. The discharge will be uniform and fine by the blocking of the insulating medium.

Daily maintenance and attention

1. Corona treatment is a device with high voltage，it is strictly prohibited to touch the high voltage terminal and electrode in case of electric shock.
2. The black terminal must be reliably connected to the metal body of the equipment and the ground.
3. Only professional technicians can open the generator and discharge rack for repairing.
4. The grounding terminal of the generator and discharge rack should be reliable grounder, otherwise there will be induced electricity
5. The corona roller shouldn’t be long time stopped if there is still discharge. Otherwise the roller will be easily broke due to local heating and burning.
6. The high voltage wire is strictly prohibited to touch the middle voltage wire and corona roller speed sensor wire, otherwise the high voltage discharge will damage the machine.
7. Excessive dust accumulation on the discharge rack can easily cause moisture and leakage. Check and clean it each week.
8. Transformer exhaust holes are usually sealed with oil sealing paper, it can prevent moisture from affecting the use of transformers.
9. Combustible materials (gases, liquids, solids) are not allowed around the corona system.

Common problems and solutions

Over temperature
It indicates the internal heat sink temperature is higher than the set value. It should be power off and check the exhaust system.
Over current
LED3 light will be on, it means that inverter circuit current is higher than limited. The power should be off firstly and then check the power circuit to see if there is any component damage.
Low frequency
LED4 light will be on. Protection function is caused by low working frequency due to load (partial discharge). Press fault reset button and then restart the machine.
Loss of lock
LED5 light will be on. The frequency tracking failure caused by load breakdown or high-voltage circuit arcing. Press fault reset button and then restart the machine.

Stop-running protection function
Discharge occurs locally on the corona roller due to roller stop. There will be no power output to prevent high voltage breaking the roller. And the ‘STOP’ LED on the SCR control board will be on. After the roller started rotating, press the start button to create discharge again. Adjust the P5 potentiometer on the SCR control board can adjust the delay time of stop-running protection.
Electrode open
The gap between electrode and roller is bigger than set value. There will be no power output and the ‘OPEN’ LED on the SCR control board will be on. Adjust the gap and restart the machine.
Phase loss
The power supply is phase loss during operation and the machine will stop working. LED2 on the function board will be on, check the power supply and restart the machine.
Phase stagger
When the machine is firstly installed or reconnected to a three-phase power supply, phase stagger may happen. LED1 on the function board will be on. The power should be off and exchange each two wires to check the problem.
Other problems and solutions