gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
120706-0933 EDT
To somewhat restate and maybe clarify my original post.
The substation that supplies my son's shop burned up.
The following on-line news article provides an outage map, a photo of a portion of the substation, and a lot of ignorant comments. Don't bother looking at the comments. However, one comment was relative to a U of M Dialysis office. They had to manually finish and send the clients home. Why no backup generator?
http://www.annarbor.com/news/power-out-in-parts-of-ann-arbor/
As I stated before we have a 3 phase Y primary supply to the shop property from said substation. From this primary two pole mounted transformers provide an output 240 V open delta with a high leg. One large transformer with a center tapped secondary supplies the 240/120 single phase loads to the building. A somewhat smaller transformer supplies the high leg. A very common procedure in our area. If the three phase load increases, then a third transformer is added.
With this arrangement before the substation fire our voltage on the three phases was typically 240 V. The difference between phases was typically under 2 volts under varying load conditions. The 2 V difference statement does imply what is the voltage of a particular phase, it is the relationship of the phases.
The substation can not be repaired for a substantial time. Thus, the fix was to tie this substation's load on to one or more other substations. I believe from what happened yesterday that our substation's load was split up between several other nearby substations.
After power was restored by connection to another substation, without knowing exactly where that other sub is, I am guessing about an additional half to one mile of wire was added to feed the loads on our burned up sub. This does not mean that I think they went out and put up a mile of wire. Rather they just found a convenient point to jumper between the subs.
If we had good voltage balance between our three phases before the fire, if there is good voltage balance between the phases at the substation that we were tied into, certainly to be expected, then we should have good balance of our voltages after the tie in. Good balance we do not have, and DTE agrees our unbalance is not expected or satisfactory.
What is the cause? Unknown at this time.
New problem occurred yesterday morning at about 4:30 AM when a major electrical (lightning), wind, and rain storm came thru. Lost power again. That put total DTE outage yesterday at about 225,000. Down to about 100,000 today. But there are a very large number of small outages, 1 or 2 homes.
Our shop outage remains. Today is supposed to be the hottest day of the year. Shop power is not scheduled to return until the end of today. Likely a delay to minimize the loading on whatever substation to which we were connected. My daughter's power was restored last night. She lost power at the 4:30 time yesterday and is only about 1 mile from the shop, but on a different substation.
When power is restored we will see if there is any change in the shop voltage balance.
A somewhat different related subject. My son has a cheap Northern 5 kW generator. He set this up at the shop to run lights and computers. But the UPSs would click on and off. There was substantial voltage fluctuation, also probably frequency. You could hear the engine hunting. Loading did not solve the problem. Put my 1 kVa Sola on this and output voltage was excessive and not correctly regulating. High output voltage was from generator being at somewhere near 63 Hz. Also could not start a single phase air conditioner from this generator.
Then we took my Honda 5 kW to the shop. This ran at 61 Hz with good voltage stability, and the UPSs were happy. Now had lights and computers. But this 4 AM storm had cut power to my daughter's house. Took my son's generator to my daughter's house and it was sufficiently good to power her refrigerator and her neighbor's. The Honda was able to start the air conditioner, but not restart after a short off time of the air conditioner. It would be too marginal to use. Would need a bigger flywheel.
Later we need to see if the Northern generator can be stabilized.
Our problems are minor compared to those south and east.
.
To somewhat restate and maybe clarify my original post.
The substation that supplies my son's shop burned up.
The following on-line news article provides an outage map, a photo of a portion of the substation, and a lot of ignorant comments. Don't bother looking at the comments. However, one comment was relative to a U of M Dialysis office. They had to manually finish and send the clients home. Why no backup generator?
http://www.annarbor.com/news/power-out-in-parts-of-ann-arbor/
As I stated before we have a 3 phase Y primary supply to the shop property from said substation. From this primary two pole mounted transformers provide an output 240 V open delta with a high leg. One large transformer with a center tapped secondary supplies the 240/120 single phase loads to the building. A somewhat smaller transformer supplies the high leg. A very common procedure in our area. If the three phase load increases, then a third transformer is added.
With this arrangement before the substation fire our voltage on the three phases was typically 240 V. The difference between phases was typically under 2 volts under varying load conditions. The 2 V difference statement does imply what is the voltage of a particular phase, it is the relationship of the phases.
The substation can not be repaired for a substantial time. Thus, the fix was to tie this substation's load on to one or more other substations. I believe from what happened yesterday that our substation's load was split up between several other nearby substations.
After power was restored by connection to another substation, without knowing exactly where that other sub is, I am guessing about an additional half to one mile of wire was added to feed the loads on our burned up sub. This does not mean that I think they went out and put up a mile of wire. Rather they just found a convenient point to jumper between the subs.
If we had good voltage balance between our three phases before the fire, if there is good voltage balance between the phases at the substation that we were tied into, certainly to be expected, then we should have good balance of our voltages after the tie in. Good balance we do not have, and DTE agrees our unbalance is not expected or satisfactory.
What is the cause? Unknown at this time.
New problem occurred yesterday morning at about 4:30 AM when a major electrical (lightning), wind, and rain storm came thru. Lost power again. That put total DTE outage yesterday at about 225,000. Down to about 100,000 today. But there are a very large number of small outages, 1 or 2 homes.
Our shop outage remains. Today is supposed to be the hottest day of the year. Shop power is not scheduled to return until the end of today. Likely a delay to minimize the loading on whatever substation to which we were connected. My daughter's power was restored last night. She lost power at the 4:30 time yesterday and is only about 1 mile from the shop, but on a different substation.
When power is restored we will see if there is any change in the shop voltage balance.
A somewhat different related subject. My son has a cheap Northern 5 kW generator. He set this up at the shop to run lights and computers. But the UPSs would click on and off. There was substantial voltage fluctuation, also probably frequency. You could hear the engine hunting. Loading did not solve the problem. Put my 1 kVa Sola on this and output voltage was excessive and not correctly regulating. High output voltage was from generator being at somewhere near 63 Hz. Also could not start a single phase air conditioner from this generator.
Then we took my Honda 5 kW to the shop. This ran at 61 Hz with good voltage stability, and the UPSs were happy. Now had lights and computers. But this 4 AM storm had cut power to my daughter's house. Took my son's generator to my daughter's house and it was sufficiently good to power her refrigerator and her neighbor's. The Honda was able to start the air conditioner, but not restart after a short off time of the air conditioner. It would be too marginal to use. Would need a bigger flywheel.
Later we need to see if the Northern generator can be stabilized.
Our problems are minor compared to those south and east.
.
