Neutral Grounding Resistor - Electrical engineer input?

[csund]

I have a larger system and work a rotational schedule out of state. I have two 20amp circuits to the aquarium on GFCI breakers. I've intentionally chose not to include equipment that would add a path to ground to prevent nuisance trips while away. In fact, I don't want them to trip even if there is stray current in the tank. I would rather be notified of the stray current and make the corrective action myself.

I'll start this with this, I work in power generation, so I have some understanding, but I'm not an electrician or engineer. On some sites, they use neutral grounding resistors/relays. From what I understand, this provides high resistance to ground, in the event there is a ground fault, the relay picks up the current via a CT. The contacts on the relay are used to "notify" the operators of issue.

I would like to build one and tie into controller and activate some sort of visual warning nearby the aquarium. This would aid in t/s while remote and isolating the failed component to prevent injury, damage or loss at home.

Has anyone built something like this, or thought about building something like this?

 

[Gumbies R Us]

@Troylee

 

[BeanAnimal]

Let me try to explain without getting into the weeds

You are describing is typically used in three phase systems. The NGR is applied to the neutral of a transformer secondary to limit ground fault current. But this assumes a grounded system to begin with. It is the opposite of what you are trying to do, or at least makes it more complicated.

What you want (or at least are asking for) is an isolated (ungrounded) system. This would be done with an isolation transformer.

Note: This is the mode that a typical UPS runs in while on battery. The system neutral is derived from the UPS, not the bonded neutral (ground reference) from the service.

So this would still use a CT or a simple sense resistor to ground on the secondary neutral. It would feed a comparator or controller. Voltage present = fault.

All of that said, this is well beyond what should be discussed in reef forum. There are safety concerns and design and implementation should be done by a fully qualified person.

 

[W31Olds]

You might consider replacing your GFCI wireless resettable GFCI Breakers and I would also add a leak detection system. Monitoring induvial Device Current could also be done but would probably get expensive and I don't know if it would add much value. If I traveled for work the biggest single thing I would do is add a Whole House Generator.

 

[BeanAnimal]

An easier and likely safer approach would be to isolate individual devices to their own GFCI receptacle and/or circuit breaker, with or without monitoring. You get human safety and the ability to isolate faults. Use redundant components for any system critical devices like return pumps, heaters, tank flow.

My system was set up this way:

• (3) 20A branch circuits, none loaded beyond ~10A
• (6) GFCI receptacles (one per pair of circuits)
• (18) individual DIN mount circuit breakers 2A to maybe 5A depending in device (3 per GFCI)
• Each control circuit had a CT, HOA switch, and control relay

This could be easily adapted to 18 GFCI receptacles if per device protection is preferred.

 

[BeanAnimal]

 

[BZOFIQ]

Impressive indeed.

I too am running on 3 separate circuits divided into multiple GFCI banks but didn't do a per device overcurrent protection as I have everything controlled by APEX and there would not have been any benefit.

You probably have a reason, although I don't see it in a sealed enclosure, but they do sell blank-face GFCI for the purposes you demonstrate here. There is also DIN mounted stuff but at a different price point altogether.

Either way, love seeing stuff with this much attention to detail!

Can we see the door on the other side?

 

[BZOFIQ]

You might consider replacing your GFCI wireless resettable GFCI Breakers and I would also add a leak detection system. ...

WiFi Resettable GFCI? Do tell

 

[BZOFIQ]

Monitoring induvial Device Current could also be done but would probably get expensive and I don't know if it would add much value. If I traveled for work the biggest single thing I would do is add a Whole House Generator.

You can monitor 32 circuits using Brultech solution. Easy to implement for the tech minded.

GreenEye Monitor (Residential)

The GreenEye Monitor (GEM) is a multi-channel energy consumption monitor. NOTE: For single or split phase services only. The versatility of the GEM makes it ideal for a variety of applications: The…

www.brultech.com

You get things like this and much more with historical data going back years.

This is today - so far; can you tell what is responsible for my high electricity bills?

 

[BeanAnimal]

Impressive indeed.

I too am running on 3 separate circuits divided into multiple GFCI banks but didn't do a per device overcurrent protection as I have everything controlled by APEX and there would not have been any benefit.

You probably have a reason, although I don't see it in a sealed enclosure, but the do sell blank face GFCI for the purposes you demonstrate here, there is also DIN mounted stuff but at a different price point altogether.

Either way, love seeing stuff with this much attention to detail!

Can we see the door on the other side?

The original plan was DIN rail GFCI breakers per device. There insanely expensive and made the wiring more complex. I had a 20 pack of the GFCIs you see there, so used them instead of purchasing dead fronts.

The enclosure is NEMA 4X

This relays were attached to my DIY modular controller that went through various stages of technology upgrades. PC opto-isolated output cards, software written in VB.Net, the Atmega128 modules, etc.

Not a great view, but you get the idea.
GFCI status undicators.
IO status for each switch
CB (out present) status for each switch

 

[BZOFIQ]

The original plan was DIN rail GFCI breakers per device. There insanely expensive and made the wiring more complex. I had a 20 pack of the GFCIs you see there, so used them instead of purchasing dead fronts.

The enclosure is NEMA 4X

This relays were attached to my DIY modular controller that went through various stages of technology upgrades. PC opto-isolated output cards, software written in VB.Net, the Atmega128 modules, etc.

Not a great view, but you get the idea.
GFCI status undicators.
IO status for each switch
CB (out present) status for each switch

I hear you about the GFCI DIN cost!

Very nice still!!!


I just wired "sensing relays" into one of the many APEX system so if any of my GFCI pops I get notified locally and remotely via text/email/pushover.

 

[BeanAnimal]

You can monitor 32 circuits using Brultech solution. Easy to implement for the tech minded.

GreenEye Monitor (Residential)

The GreenEye Monitor (GEM) is a multi-channel energy consumption monitor. NOTE: For single or split phase services only. The versatility of the GEM makes it ideal for a variety of applications: The…

www.brultech.com

You get things like this and much more with historical data going back years.

This is today - so far; can you tell what is responsible for my high electricity bills?

The CT selection and board for that operator panel was originally designed to work with green eye. I never ended up buying their product and instead wrote my own.

 

[W31Olds]

 

[csund]

Let me try to explain without getting into the weeds

You are describing is typically used in three phase systems. The NGR is applied to the neutral of a transformer secondary to limit ground fault current. But this assumes a grounded system to begin with. It is the opposite of what you are trying to do, or at least makes it more complicated.

What you want (or at least are asking for) is an isolated (ungrounded) system. This would be done with an isolation transformer.

Note: This is the mode that a typical UPS runs in while on battery. The system neutral is derived from the UPS, not the bonded neutral (ground reference) from the service.

So this would still use a CT or a simple sense resistor to ground on the secondary neutral. It would feed a comparator or controller. Voltage present = fault.

All of that said, this is well beyond what should be discussed in reef forum. There are safety concerns and design and implementation should be done by a fully qualified person.

Thank you for the input. Yes, these are all three phase 13.8kv. When I looked initially, I didn't find any info for single phase. It looks like I didn't completely grasp the function either. I'll look into DIN mounted GFCIs, I use the discontinued GHL power hubs and DIN mounted power supplies so everything is currently mounted on DIN rail.