AC Drives troubleshooting

Basically this week, I'm helping one of the supervisor in the instrument department, Mr. Lee Yoon Kian to troubleshoot the AC Drives. The AC Drives that are malfunction will be sent to the instrument calibration room for maintenance.

First of all, Mr. Lee checked all the I/O control cards in the AC drives to make sure that all the I/O control cards are good in condition. If the cards were burnt, the new I/O card will be replaced. If the cards are OK, then Mr. Lee will proceed to the next steps. He will start checking the IC on the control card. In some cases, the control card is OK, but the problem happen on the IC on the board, which may be burnt or spoiled, result the control card couldn't function well and causing the malfunction of the AC drives.

If the problem still haven't detected after troubleshooting the control cards and ICs, he will start checking the parameters in the ICs. Due to some technical problems, sometimes the codes and the parameters in the IC will be imprecise and incompatible with the motors and drives. So the new parameters have to be re-uploaded into the IC using the DMS software, a software used to download or upload parameters from/to the IC.

Until here, if the problem still couldn't be identified, he will check the chopper part and the transformer in the AC drives. The capacitor banks in the chopper will be opened up to determine whether the capacitor banks are still functionable or whether the terminal + and — are connected in the right manner, or the types of capacitor banks is correct (Ex: 15µF). To make sure every steps he performed are correct, he usually accompany a user manual with him because the AC Drives use a very high voltage and power. It will be dreadful if anythings go wrong~

DC Drive Training By Yaskawa

I had attended a training about DC Drive conducted by the Yaskawa Electric (S) PTE LTD supplier. This was a 2 days training program which included classroom training and the site training. Actually, this training is main for the engineers and technicians who are going to deal with DC Drive in the DC Drive control room and I'm so lucky to be picked to join the training together with the professionals. We had been introduce to the basic concept of the DC drive in the classroom training and a presentation about the concept was presented by the supplier as well.

DC Drive are the DC motor speed control system. Since the speed of a DC motor is directly proportional to armature voltage and inversely proportional to the motor flux (which is a function of the field current), either armature voltage or field current can be used to control the speed of the DC motor.

The advantages of the DC drive over direct drive to motor are:

1. smoother operation
2. acceleration control
3. different operating speed for the each process recipe
4. compensate for changing process variables
5. allow slow operation for setup purpose
6. adjust the rate of production
7. control torque or tension
8. saving energy

Besides that, the trainees also been taught the method to troubleshoot the problems of the DC drive. The trainer provided us a guideline and a table contains the symptoms of the failure and the remedy to solve the problems. During the the site training, we got to try on setting up the parameters and settings of the drive. However, due to some improper use of tools and improper construction of circuits, the motor did not work in the way we desired and there were sparkings appear on the motor!! Scary~ I was really really afraid there's gonna be some sort of explosions happen on tat moment, however the power supply quickly been turn off by the experience technicians and everything stop till there.

Well, it do remind me again the important to use the proper tools when you deal with circuit and electricity AND....
Make sure all the cables and electric components are connect in the way they should be connected before you turn the power on... or else
the sorrows of life may just happen like that...... unexpectedly!
hahaha~