When Design Fails

I started the electrical concept definition of the Mariwasa-Siam ceramic manufacturing plant in Santo tomas, Batangas, Philippines in 1990 under the supervision of the late Engr Sirio Reyes (PEE/PME). The total calculated load of the plant is approximately 6MVA.

In that time, the national power reserve was low, the possiblity of an outage was very high. Critical operations need to have emergency generators or some other companies constructed their own base load power plants within their manufacturing facility. The new Mariwasa manufacturing complex was not different, there was a plan to construct a base load power plant after the manufacturing plant has been commissioned.

In my concept design, I added this feature as a future add-on. There is a change over from the 34.5kV mains to the proposed 4.16kV Base load plant and vice-versa. In this case, the 34.5kV supply need to be stepped down to 4.16kV, thus a 6MVA mains transformer has been installed.

Other features of the concept definition was to install all distributions underground. It was expensive but will make the new manufacturing complex free of overhead distribution lines and electrical poles. The only overhead lines would only be up to the Meralco – Mariwasa connection point which is located at the one corner of the complex far from main traffic.

I was able to complete all the concept definition plans. Actually, I used this plant as my Electrical Design report for my Professional Electrical Engineer board examination in April 1991 where I got First Place.

There has been so many changes in plant layout. Engr Benjamin Navarro, the Assistant Vice President in charge of the project has so many revisions in his office I will not even bother to count.

The people developing the concept were

1. Engr Sebastian Rayos, Senior Vice President
2. Engr Sirio Reyes (RIP), Technical Consultant
3. Engr Benjamin Navarro, AVP Plant Engineering
4. Engr Silverio Pangonilo, Plant Electrical Engineer
5. and a couple of people doing drafting…

Note: Due to the delay of the project, all of us have already left the company. Engr Rayos retired but later did consulting jobs for the project. Engr Reyes has left this world. Engr Navarro and I also left the company before the implementation of the project.

As most of us have already been out of commission on the project, the Mariwas management has decided to award the project design to an engineering consultant to do detail design including electrical.

My concept design was actually transferred into the engineering consultants title block and made it their own. I knew because I was once part of the electrical construction team. I knew my concept and I knew my design.

When most of the major equipment were already purchased, there was a change of events. The construction cost was too costly that Mariwasa management ordered the engineering consultant in charge of design to modify the installation detail from underground to overhead.

A very good innovation, isn’t it. A very economical one.

There was a principle in design which the engineering consultant failed to implement, to change the distribution voltage from 4.16kV to 34.5kV. The original cable sizes were then too large for an overhead installation at 4.16kV.

If you visit the Mariwasa-Siam site, you will be able to see a 25kVA pole-mounted transformer being supplied by a 1000MCM ACSR.

This is a clear example of a design failure. It is alright to heed to the requirements of the client but changes should be implemented intelligently not blindly.

Probably, the electrical engineer of the consulting company have not used his logical thinking when he decided to change from underground to overhead type of distribution. This plant will be a living legacy of a design failure for the nex couple of decades.