If the NEC is applicable, it seems that you would need to run a conductor to serve as an "Equipment Grounding Conductor" if you don't use a multigrounded neutral system.
Not sure. Only info I have is what's on the nameplate.
Thanks for the explanation, it's definitely helping me understand what caused current on the NGR.
The amazing part is this thing has been connected for the past 10 years or so, with no issues until now.
400A is the NGR nameplate rating - 277V, 400A, 0.7 Ohms, 10 sec.
There is a single H0X0 terminal in the secondary compartment, which was connected to the "neutral" side of the NGR.
Yup, that's what I thought. I'm definitely telling them to remove the NGR and go solidly-grounded.
That's my thinking too.
I'm aware, I'll definitely be correcting this one way or another.
Your theory about the NGR overheating and damaging the cables makes perfect sense to me.
Sorry for the poor notion. The 33 kV source is 4-wire grounded wye. The 33 kV neutral is connected to the ground...
Posted this on another forum already, but figured I'd look for insight here as well. A customer of ours had the conductors that connect to their neutral grounding resistor burn up. The 480V system is configured as a high resistance grounded system that consists of loads and generation (landfill...
If the SEL-351S is ONLY performing 50/51 functions, then there is no issue with physically swapping the polarity of the CT. No relay settings will need to be changed.
It doesn't look like you're able to change the CT polarity through the settings for the SEL-387E.
I recently completed a design for a similar situation. The customer needed protection from small blinks and enough ride-through for their generators to start and sync. We looked at Piller, Hitec, and S&C.
After looking at total cost of ownership for each route, we based our design on a Piller...
Thanks for all the responses, definitely some good information!
I'll start by saying that this is not for a utility substation, it's actually for a MV rotary UPS at an industrial facility. The wiring in question must run from the UPS SWGR enclosure to the UPS enclosure (SWGR and UPS will be...
Marks, thanks for all the info. Understood, we'll ground the CT wiring on both ends and keep the bonding conductors as short as possible.
What's your opinion on the PT wiring? Seems like it might be wise to only ground one end since they should be carrying almost no current.
Thanks for the response!
Are you sure about only grounding one end of the shield though? The majority of what I've read so far recommended grounding both ends in this situation, at least for the CT wiring.
A typical 4-20mA signal cable should definitely only be grounded on one end, so it...
Is it recommended to use shielded cable for CT and/or PT secondary wiring?
I'm working on a design for a small substation that will have MV cable and CT/PT/control wiring in the same concrete encased duct bank. Obviously the MV will be in separate conduits from the LV wiring. What's the minimum...
