A utility customer is considering installing an neutral ground reactor on one of their distribution transformers (12.47kV).
I'm familiar with NGR in several other applications but have not seen many of these installed on distribution transformers. Is it common for utility's to have NGR's on...
I'm looking into a temporary mobile substation to temporarily restore power to a site with 60kV utility incoming stepped down to 12.47kV for distribution to facility. Mobile sub would consist of 60kV breaker, 5MVA transformer and 12.47kV secondary breaker.
The only option for temporary...
On an industrial or renewable site that is served from the Delta side of an interconnection transformer and has a grounding transformer (wye -delta) for sourcing ground fault current and limiting overvoltage, is an equipment ground conductor (EGC) as required by NEC still appliable to this...
I've been looking at several wind projects that use Type 3 (DFIG) and Type 4 (Inverter) generator types. From what I've read both of these types of generators have limited fault current contribution capabilities due to the presence of the inverters.
I've been familiar with limited fault...
I was wondering what standard practice was for grounding of neutral connections on utility pad mount transformers served from and overhead distribution line that contains a neutral. Question applies 1-phase pad mount fed from OH lateral feeder but similar question also applies to 3-phase with...
Is anyone aware of an analytical or modeling approach for evaluating location of arrestors on overhead distribution lines? Most approaches I've seen have been ones that utilities have adopted over years or more general "rules of thumb" but was curious if there was an analytical approach using...
I'm in the process of determining size of 480V diesel genset for an industrial site to replace existing temporary units. I'm evaluating size based on both metering data captured via a portable power meter for site at service entrance as well through load calculation in order to evaluate both...
Looking at an application where a new 24.9kV - 12.47kV transformer is being added for interconnection of wind farm to utility 24.9kV distribution line. Transformer is 15MVA and will have delta side facing generation (with grounding transformer on that side) and the wye side facing 24.9kV...
This is a question which I've wondered about for quite some time and although I think the answer comes down to commercial agreements as opposed to flow of electrons I was curious to hear from some of the experts here.
As an example I've heard of scenarios where a new generation plant or...
I know that the NEC requires additional Equipment Ground Conductors (ECG's) to be run with any feeders between equipment and Supply Side Bonding Conductors (SSBJ) to be run between transformers of separately derived system and downstream equipment.
My question is in a HV substation environment...
I’m looking at a project where customer is looking to install temp 138kv-34.5kv transformer in existing substation in order to repair existing transformer. Plan is to locate tramp transformer in separate location in yard and reconnect HV and MV bushings to existing buses work to minimize...
I know that for applying a PT on a 4.16kV impedance grounded system (non-rigidly grounded)the PT needs to be a 2400/4160Y PT as opposed to a 2400/4160GY PT due to the fact that the neutral bushing needs to be a fully rated bushing for when neutral floats to line voltage during certain fault...
In relation to my other recent post I'm looking at an application where there are (3) 3MW wind turbines connected to a 12.47kV collector feeder before interconnecting to a 12.47kV distribution line (there is actually a voltage regular between turbines and utility line to bring 12kV turbine...
Is it possible to implement transformer differential protection using (2) reclosers on high and low side of transformer?
Looking at application where existing 15kV recloser would be on low voltage side of new 15MVA transform and consideration adding new 25MVA recloser on 25kV high side for...
I'm looking at an application for a distributed generation wind site that currently has about 12MW of wind generation at 12kV that goes through collector system and step voltage regulator before interconnection point of 12.47kV utility distribution line (recloser and metering at interconnection...
I’m in the preliminary stages of concept design for new 345KV GIS substation and was hoping to hear any experiences or best practices others have had with GIS layout.
Substation topology will be incoming 345kV lines to GIS which will then feed (4) distribution transformers.
Proposed method...
Does the NESC have any specific requirements for 34.5kv pvc conduits encased in concrete ductbank beyond what is required by NEC?
NEC allows for 24” min burial depth for MV pvc conduits that are encased in 2” of concrete. Does the NESC require any greater burial depths?
Are there applications where it is permissible for use MV-105 cable at the listed 105C temperature rating? My understanding has always been that the 105 deg C rating could be used for de-rating purposes however cable was limited to 90deg C rating due to MV terminations being listed for 90C?
If...
I'm specifying wye-wye PT's on a 34.5kV system that is a Delta system but grounded through a zig-zag transformer with NGR. Can these PT's be standard 20125/35000 GRD Y single bushing PT's or do they have to be a 2-bushing PT for potential elevated L-G voltage during a ground fault?
I know...
I’m looking at 706.30(B) and trying to determine requirements for over current protection on cables between a batteries and an inverter system.
The way I read and understand it is that the size of the cables and overcurrent device is based on the inverter rating and what the inverter is capable...
