Interested to Buy Any Domain ? << Click Here >> for more details...
What is the purpose of SOTF being used inspite of distance
Protection given?
- 7 Answers
- 50157 Views
- Alstom, I also Faced
- E-Mail Answers
Answer Posted / ofa khoirun niam
Dear Engineers,
SOTF also known as Switch On To Fault is one of the protection type feature. How it works? Let's see this. During closing or energization on the line in which fault is happening within 20 ms from CB closing, then SOTF feature will clear the fault by opening the CB as instantaneously manner, even if the fault is happen in the zone 1 or zone 2. When the faults happens after 10 or 20ms, CB will opened instantaneously by Line Distance Zone 1 feature when the fault location in Zone 1 or CB tripped with time delay 300 ms to 500 ms when the fault happens in Zone 2.
This type of protection schemes are mostly working while re energizing the line after maintenance if earth switch not opened at other end of line (or maybe another fault happens) . Normally this will be in Zone 2 of distance as Zone 1 will cover only for 80% of line so in this case SOTF will act faster than distance.
Why SOTF should be provided and why distance (21L) feature could not be used. Because there is no impedance could be detected by Distance (due to CB in opening position, no current is flowing). And also there is no line voltage when the fault is caused by earthing switch (ES) in closed position in the opposite Substation, maybe missing by operator forgot to open the ES.
Wthout SOTF feature, line protection could not operate to trip the CB, even breaker failure also will no work or not be initiated. It very possible to resulting in time delay around 20ms until Line distance working properly. massive unit instability maybe occur.
So, SOTF is one of the feature relay should be tested during commissioning the HV Substation Protection Relay. I hope my explanation could be very easy to be understood. CMIIW
Best Regards,
Ofa Khoirun Ni'am
Electrical Engineer
| Is This Answer Correct ? | 5 Yes | 0 No |
Post New Answer View All Answers
why is using sensor?what is differece between photoelectric and proxmitty?
1.Z transform always lies around ? a) origin b) pole c) zero d) z=1. Multiples Mcqs which is bother me can’t find answers on internet. Some help required with little explanation . Note: this is not homework or related to any test. Thanks
what is the safe meggar values for motor, transformer HT, LT and Cables? IF we want to replace I/C bay at our 220 kv substation which is of 140 mw load capacity bay to be replaced by 400 mw capacity bay.other than CT(1200/1) what are the other equipment i have to replace. why we generally use 3.5 core cable or in other word 1/2 core for neutral and also confirm me that in balance conditiob(3 phase)current in neutral will zero
I have made a 3 phase thyristor full bridge rectifier. But at the moment it is working only for the half bridge operation. Both the half bridges are on operation separately but when i put it into full bridge operation the oscilloscope output is zero. I rechecked that the pulses are correct for each thyristor. what could be the possible reason for this?
Please tell me the formulaes while designing a substation for power Calculations in designing a 33 KV Substation?????
Whar is the KvA rating of 33Kv substation & actual kv rating of power generaating station.
distribution is maximum done by a)radial b)network c) parallel d)b & c
I have 2500KVA transformer delta/star,13.8KV/380V provided with LV 4000A breaker. Already I have 2300KW motor feeder with a full load 90%. Is it possible to connect another 1600A from that breaker? If so how the calculation is done?
Why to keep capacitor bank off while generator running.
Please tell me in DETAIL about the following 3 types of fuses or recommend me a good power system protection book or a website link ? 1.Dropout Fuse 2.Striker Fuse 3.Empulsive fuse (not sure if its impulsive or explosion fuse , sorry)
1)How much current can a 3-1/2 core 100 mm wire carry? 2)What are the special cables required for explosion proof wiring? 3)In case you do not have coal and salt for earthing, how can you achieve good temporary earthing? 4)One horse power single phase motor is more likely to get hot than a one horse power 3 phase motor. Is it true or false, if true why? 5)What are the different types of soft starters for large motors?please explain?
placing earthing pit in pathway is correct or wrong??. placing earthing wireGI1/18 inside walls is correct or wrong?. explain!!!
what are the things that can cause a three phase motor to crawl?
What is the tests required for a 132 kV, 400 kV , 765 kV for a Circuit Breaker and Power Transformer before commissioning ?
what is errection pcbs?
