True Professional Engineer
This is a blog to share my experience in manufacturing / industrial engineering and management system setup.
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Tuesday, June 27, 2017

Power supply to control system

With the introduction of  PLC (Programmable Control Logic) into industrial automation, the use of 24 VDC power supply become a norm.

Industrial automation company such as Allen Bradley and Siemens, together with others companies like Phoenix, Omron and etc. do supply high quality power supply units. These are normally quite high in cost and they are claimed to be "more safe and stable".

After all,
  1. Are this claims justify the duty they provided?
  2. What is the differences between this and normal 24 Volts DC power supply unit?
  3. Is there any possibility that we can repair the power supply unit ourselves?
On browsing the internet, I come across this Power Supply Repair E-Handbook and believe it will give you the answer. You can checkout here to buy the product.

Note: sometimes, the links provided might be not accessible due to some WIFI setting. In such case, try it again when you are in a different WIFI coverage.

Monday, June 26, 2017

High technology problem after a electrical power shutdown

A recent expansion called for incoming electrical power shutdown for installation of new VCB (Vacuum Circuit Breaker).

It had been a normal practice that engineering team has to standby to rectify issues caused by power shutdown. I always refer to this as the "high technology problem", because this type of problem seldom happen to the traditional equipment with hard wired control circuit.

As the digital technology advanced, a lot of control had been digitized. More and more companies are now promoting the "4th Industrial Revolution". I believe that this is the right direction but sometimes I cannot stop myself doubting on how many of those involved really understand the practical problems behind this development.

Digitizing means more electronic components are used in plant automation. The advantages for electronic components are low power consumption, higher flexibility in equipment production and modification.  Nevertheless, digitizing also means that higher chances of component failure caused by electrical surge.

With a high number of PLCs and VFDs used in the plant automation, it had been a norm that a few VFD fail after power shutdown. This time, five VFDs need to be replaced.

The same happen to earth leakage and over current relays. One unit is replaced this time.

There may be someone thinking that it is caused by unhealthy electrical quality. The fact is we had carried out various electrical quality check and the same problem never end.

One other problem that frequently faced is the Ethernet communication used for production line PLCs and VFDs. The lines are fully auto, with ability to set in recipe which is known as flexibility. But the system tends to lost communication. Sometimes problem is rectified by replacement if Ethernet switches, but quite often the issue is solved by a few restarting of the control system and/or unplugging and plugging of Ethernet cables. We believe this is not a professional method, but it works.


New start to an old blog

This blog had been created for sometimes. For various reasons, it had not been updated effectively.

Today, I had decided to re-design its outlook and you can notice a lot of books appeared as its background on the bookshelf. This is one of the main reason because there are so much to share and yet there is so little time to write post.

Believing that Rome is not built in one day, with this new start, I will post idea as it appears and will progress to share any information which I find useful and believe they will help my audiences as it progress. Any comment will be welcome and I will try my best to improve along the way.

Trouble shooting for mechanically jammed Serpentine oven

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