Our electric utility is in Southern Africa and we have some subtransmission lines (66kV, 88kV and 132kV) that span through areas with high ligtning flash density and every rain season, we experience abnormally high line outages due to lightning coupled with porcelain insulator damage. The line...
Well, you could be right Stevenal about the sizing of the resistor and contacts. But looking at the statement from the J & P transformer book, they're also taking about reducing the rating of the tranformer if power flow reverses, is someone able to explain how this comes about because they dont...
Thanx RalphChristie and Stevenal for your contributions. We have contacted the suppliers about the possibility of modifying the tap changer wrt the resistor connection to see if it can work in the step up mode. But just following up on RalphChristie's contribution, how does reversal of the power...
Thankyou Cuky200. This site however has little info on OLTC's. It seems they more into voltage regulators, i.e. automatic (or universal) voltage regulators (AVR or UVR). The info I am requesting for is to do with the actual on load tap changer itself as an intergral part of the tranformer and in...
Hallo forum members,
We have recently procured two 25MVA 66/33kV power transformers from a supplier in India. The transformers have an OLTC of single resistor type and they have put a caution that it is suitable for unidirectional power flow i.e. from HV to LV and not in the reverse. We however...
The mode of failure is one where the interupting chamber explodes. In two of the fauires two interrupters exploded and the debris affected the third column which was partialy damaged in the process. Now my concern was that perhaps these breaker may not have been properly dimensioned for this...
We have been experiencing failures of a particular design of 72.5kV (Alstom FX10) Sf6 breakers installed on our 66kV system. Two units are used to switch 36MVar shunt reactors connected to the 66kV bus, two are on the transformers and the other five are on feeders. These breakers were...
