Is there an advantage to having a neutral reactor as opposed to a neutral resistor on a distribution circuit?
From what I've seen this is commonly done with generators where the Z0 is much less than Z1 causing zero sequence current to be much higher than positive sequence current and this the...
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...
Good points on shield.
I'll have to look into concentric neutral as use as 2 conductor assembly but I do recall seeing recently that NEC permitted its use as an EGC. If that is the case is it still cheaper to run a separate EGC than use a concentric neutral cable just for the purpose of...
Thanks.
In my application I have a 4-wire distribution service coming into site and assuming distribution is a Mult grounded system. This incoming line hits a pole mounted disconnect, then padmounted recloser before it finally hits wye side of interconnection transformer. From reading the NEC...
Thanks Waross
I'm trying to determine if the shield of an MV cable can be used to satisfy that EGC or if I must add a separate EGC cable or change cable to concentric neutral type. From what I understand the NEC doesn't allow shield to be used as an EGC to carry GF current of significant...
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...
Thanks for responses. Even is this wasn't a utility pad mount transformer but rather a pad mount transformer within the customer premises I'm assuming the answers would be the same in that the concentric neutral could be used to carry neural current and fault current in system? Or would a...
I'm curious at a high level what this analysis would involve. Would you have to look at voltage transient at each pole and evaluate along with pole grounding and arrestor rating?
Are arrestors only for protecting insulation in this application? If so why is it that I typically see arrestors located at reclosers that do not have insulation?
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...
Load measurements show maximum average current of aprox 618A equating to 514kVA. Largest motor is 50hp so adding 2X its FLA of (65A) adds 108KVA to the measured base kVA resulting in aprox 622kVA.
When adding in consideration for largest motor starting does that simply get added to base load...
The NEC for "optional standby" generators requires generator capacity to be based on NEC article 220 (demand calculations) or "other approved methods". In general article 220 requires 125% of any continuous non-motor loads.
However in seeing "other approved methods" to me means that if the...
