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According to IEEE Gold Book - Insulated Bus Bars reduces the likelihood of a bus fault by approximately 90%. Depending on your reliability requirements and cost of outage impacts, that may or may not be a significant figure. On a recent project of 100k/hr plant outage we calculated insulating...

3 phases, interconnected via various sources or load impedances etc. In an earthed/grounded system, when one phase or multiple phases are faulted to ground, current will 'flow' in all phases in-phase through the system into the fault. This in-phase current is the zero sequence current. In the...

Hi All, For the purposes of Fault Analysis, I'm modelling in etap an 11kV industrial system that until recently had embedded generation. The system is earthed via a YNd11 12.1kV / 240V open delta transformer with an LV resistor. I can't find a way to model this in etap directly with the LV...

Only speaking for my locale, but industry best practice is to always earth/ground metallic substation fences. The rationale being that unbonded fences overtime often being bonded by accident or as part of any upgrades/additions/maintenance, where the earthing/grounding design has not been...

Hi, I have read up on the use of the intersecting curves method in the Megger earthing guides and some (very old) material by Dr GF Tagg - however the method is not addressed in IEEE80/81. I have also seen a few prior posts in the forum mentioning it. I am curious to understand more detail...

You can get specialist sealing products for this kind of application like these: https://www.hauff-technik.de/en/category/cable-entries-1/press-seals-27 Sealing the cables individually with pressure fit seals is the only way you're likely to get a truly watertight penetration in the...

1. Start with basic functional earthing. 2. Calculate the fault loop impedances. 3. Calculate your earth fault return current. 4. Determine protection operating time. 5. Determine tolerable safety limits. 6. Determine EPR (Earth Fault Return Current x Earth Grid Impedance). 7. If EPR < Safety...

Hi, We have a project on-going where we will design-build a containerised portable substation for 11kV vaccuum switchgear. We have built several in the past but not been directly involved in the design. The feedback from speaking to the project managers involved in these works is that the...

This question has arisen locally in the context of separated HV/LV earth systems in utility system. The standard answers I am aware of consider the relative size of both grids. Since you wish to segregate based on the transferred potential via the earth itself, to achieve what you want, you...

Hi @james64, In general yes. However, it would be remiss to advise you to not perform a specific case analysis as part of your engineering study. To answer to your OP, the kind of simulation you require is power systems analysis, more specifically a short-circuit study. You can reference IEEE...

Interesting to hear how the rest of the world does it. Here, in my part of the world, nobody runs reduced size neutrals in LV world anymore. It is technically still allowable, you simply need to show your calculation of the neutral current, but most, if not all, consider it not worth it, given...

@che12345 1. agreed. 2. In some sites/parts of the world/industries E-Stop are used as LOTO devices. This doesn't mean they are used for start/stop or on/off operation. 3. agreed. 4. Typically lockable E-stop are lockable ONLY in the Engaged/On/E-Stop position. As predicted, hotly debated topic.

As noted above. But only where client safety procedures allow the use of Emergency Push Buttons as an isolation devices - this is a hotly debated topic (in my experience) but generally considered safe where there is emergency circuit monitoring and SIL-rated control system.

MV and crossing rather in parallel are low risk, it is probably not a concern, if further it is a multiplex/multicore I would not be concerned at all. As noted above clearance concern is more defined by future maintenance considerations and utility/owner requirements. AS/NZS 4853 is the...

CDEGS by SES is considered by many or most to be the market-leader.

Excellent idea from @PHovnanian. I was hoping for an update on this, having you done any testing yet @Ingenuity?

I don't believe there is such a standard. There are two practical concerns you may want to consider: 1. The joint will be of significantly greater diameter than the original cable. Depending on your arrangement, they may not sit side by side. 2. Access for repair. The majority of cable...

1. Cable Tray is not really required to be bonded if carrying sheathed cable and there is no mechanical hazard and it is mounted above a 2.5m height. (Unless you have a separate legislative requirement) 2. The bonding conductors cause a low impedance earth return path. This primarily for the...

1. Reviewing the Single Line, I see some notes that give indication this drawing may be retrospective and has some possible inaccuracies? 2. Is it the conclusion that the control power on the machine is fed from the wrong source (BD4 instead of BD3)? Seems to me.. 3. Does the machine have a...

The unbalanced impedance can be significant if running parallel sets of cables.