500kV Surge arrester (MOV)
500kV Surge arrester (MOV)
(OP)
Dear All,
I have a problem about using 500kV MOV for replacing pre-insert resistor of 500kV CB .
Does anyone have document, calculation method, ... or experience this problem.
Thank you
Van Giang
I have a problem about using 500kV MOV for replacing pre-insert resistor of 500kV CB .
Does anyone have document, calculation method, ... or experience this problem.
Thank you
Van Giang






RE: 500kV Surge arrester (MOV)
Please do not. The HV guys should do that.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 500kV Surge arrester (MOV)
I really want to find the document around this problem. When we close the EHV Tranmission line, the switching overvoltage is big problem and in this case the pre-insert resistor is one of a choice. However this solution is very expensive. Normally, MOV (surge arreter) for line feeder is installed already, so everybody use it to replace the pre-insert resistor of CB.
I'm worry about how can I choose the best spec for MOV in this case.
And now, I have two papers from IEEE ("Elimination of closing resistors on EHV CB - 1988" and "An application Metal oxide SA in elimination of need for closing resistor in EHV CB - 1989", however It is only the general information.
Does anyone help me?
Tuan
RE: 500kV Surge arrester (MOV)
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 500kV Surge arrester (MOV)
It is true that by using MOV line-entrance arresters you can eliminate the need of closing resistors on a majority of transmission lines from 400 kV up to 800 kV.
If you do fast reclosing (0.5 s) on long lines you need to make sure about the arresters energy capability.
Bahram7
www.simtech-intl.com
RE: 500kV Surge arrester (MOV)
Could you talk clearly about "If you do fast reclosing (0.5 s) on long lines you need to make sure about the arresters energy capability" ?
Thanks,
Van Giang
RE: 500kV Surge arrester (MOV)
Fast reclosing means that the breaker will reclose on the line with almost full trap charges. This may dissipate a lot of energy in the arrester. Utilities buy normally 2 columns line arresters at 500 & 800 kV to make sure that the line arresters will not fail during line discharges.
Bahram7
RE: 500kV Surge arrester (MOV)
A B
-O--------------------O--
When breaker A closed and breaker B still opened, maybe the highest voltage will drop on MOV of B. In restricted case, this switching voltage is about 3pu (3x449kV)in 500kV system.
You may be right. Could you tell me about the spec of MOV (two columns) which can protect against switching voltage during reclosing?
Van Giang
RE: 500kV Surge arrester (MOV)
Closing resistor is still one of the most effective methods to reduce the breaker stresses. The enclose figures show a typical performance of surge arrester and closing resistor reducing the magnitude of the overvoltage seen by the circuit breaker contacts.
http://cuky2000.250free.com/Switching_Surge_1.jpg