Flying Grounds for Transmission Line Protection
Flying Grounds for Transmission Line Protection
(OP)
We have a situation on some of our older 115KV:13.2KV substations where we are still using flying grounds in lieu of higher rated circuit switchers between our station transformers and our 115KV T-lines. Does anyone know the concept behind this original design and why it would be justifiable to upgrade to circuit switchers?






RE: Flying Grounds for Transmission Line Protection
RE: Flying Grounds for Transmission Line Protection
If the latter, the justification for changing to circuit switchers is a reduction of high level faults that stress the transmission system.
The use of high speed grounding switches is better than a system used by the supplier of one of our municipal clients. The system was to open a motor-operated disconnect when the transformer protection operated, with the idea that if the current was too high to be interrupted by the switch, the arc would go to ground and cause the transmission line protection to trip at the source.
RE: Flying Grounds for Transmission Line Protection
With power transformer costs continuing to increase and if the physical space is available I've been suggesting installation of a circuit breaker instead of a circuit switcher as I want the zone of protection extended to CT's on the breaker in order to protect for a tank-mounted lightning arrester or high-bushing failure.
RE: Flying Grounds for Transmission Line Protection
This old system have two "goals"
1. Save CB's.
2. No problem with protection coordination, you have only one 50/51, 50N/51N relay installed on the source side.
This system is common practic in Russia on radial lines up to 110kV with many xfr. on the same line.( municipal and settelments applycation only, not for industrial or transmission lines).
Regards.
Slava
RE: Flying Grounds for Transmission Line Protection
Any similarity to the one shown in the enclosed link?
http://vi
RE: Flying Grounds for Transmission Line Protection
RE: Flying Grounds for Transmission Line Protection