Way to Save Energy Bill By Power Down STand-by Transformers

[chlee-penang]

Hi,

I have a question seeking member's advice pertaining to operational safety and energy saving.

We have 4 sub-station each equipped with 2 transformers (1 station 11KV/6.6KV 10 MVA, 3 other stations 11KV/.433KV 2MVA) on 2x100% stand-by configuration , secondary feeding to two bus sections with a bus-coupler. Currently both transformers are supplying concurrently to the load with Bus-coupler OFF in one Sub-station, others carrying total connected load by one of the two transformers only.

As an effort to reduce energy cost, I intend to switch out one transformer on each Sub-station to de-energized stand-by mode, when carrying out schedule 11KV stand-by generator load test each month, taking that opportunity to rotate the duty/stand-by transformers too, by doing so, the Free Load losses of transformer can be eliminated.

The question is whether safe to leave the transformer in de-energize state for 1 to 2 month, switch it ON and OFF alternate month?

 

[Knobhead]

I'll redraw it tonight so that everyone can see the full drawing.

I don’t think the earth switches for the outgoing feeders from the generators are in the right place ether. As it’s shown there’s four earthing points for the busbars.
Once it’s done I’ll send a copy for you to check before posting it.

 

[Knobhead]

From what I can make of it.

 

[chlee-penang]

From what I can make of it.

Thanks Tony for taking the trouble to draw a clearer diagram, you are absolutely right, it is exactly as per actual installation.

The bottom portion representing a total black out from utility whereby generators are supplying to all the loads. During scheduled load test with only one generator, or managing peak hours tariff, the generator power is fed to one section of Bus Bar only, i,e, operating both utility and generator supply concurrently without paralleling the two sources.

 

[Engineer54]

Thanks Tony for taking the trouble to draw a clearer diagram, you are absolutely right, it is exactly as per actual installation.

The bottom portion representing a total black out from utility whereby generators are supplying to all the loads. During scheduled load test with only one generator, or managing peak hours tariff, the generator power is fed to one section of Bus Bar only, i,e, operating both utility and generator supply concurrently without paralleling the two sources.

How about you now showing us (using Tony's drawing) the main VCB Open /Closed positions when operating the system with both utility and generator supply concurrently. Because from how i remember your original drawing you are only using one utility incomer on site 'A' and you had some bus couplers closed on LV switchboards??

 

[chlee-penang]

How about you now showing us (using Tony's drawing) the main VCB Open /Closed positions when operating the system with both utility and generator supply concurrently. Because from how i remember your original drawing you are only using one utility incomer on site 'A' and you had some bus couplers closed on LV switchboards??

Hello brother, please refer thread #60, I paste the content here for your convenience.

"My sincere apology, it is my oversight that the red dot was accidentally moved away from VCB #8.

Normal operation conditions:

Site "A", VCB "ON" position are #6 & #8; #2 & #12;#4 & #6, feeding generator power will require changing over between #4 - #6, or #8 - #10.

Site "A", VCB "ON" position are #5 & #8; #1 & #11;feeding generator power will require changing over between #3 - #5, or #8 - #10."

 

[Engineer54]

Hello brother, please refer thread #60, I paste the content here for your convenience.

"My sincere apology, it is my oversight that the red dot was accidentally moved away from VCB #8.

Normal operation conditions:

Site "A", VCB "ON" position are #6 & #8; #2 & #12;#4 & #6, feeding generator power will require changing over between #4 - #6, or #8 - #10.

Site "A", VCB "ON" position are #5 & #8; #1 & #11;feeding generator power will require changing over between #3 - #5, or #8 - #10."

To be honest, it's too much of a hassle to keep going back wards and forwards between posts and PDF files to compare your original with Tony's modified drawing (that you say has the correct Open/Closed VCB positions). As i say, i can remember bus couplers on some of the LV switchboards being closed, where none are Closed on Tony's drawings. Which is why i asked you to show the VCB positions when both utility and generator supply are being used concurrently...

 

[chlee-penang]

Dear E54, I agree with you it's too much of a hassle to keep going back and for between posts, anyway it is immaterial to energy saving, let us close this topic rather then wasting your value time.

Thanks for your interest.