Hi,
I am looking for advice on the grounding / earthing of structures beneath transmission lines. The scenario is a 220kV line which crosses a waterway, and a temporary steel bridge structure also crossing the waterway is being installed, directly underneath the lines.
Does the NESC Handbook...
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...
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...
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...
Hi,
I am curious as to the experience of others in using multifunction testers (primarily designed for insulation resistance measurements) for measuring prospective short-circuit currents with regards to accuracy.
Typically in my company we use the Megger range of MFT (such as MFT-1835) to...
Hi,
Is there any applicable guidance notes on pressure testing in-service MV (11kV operating, 12kV rated) equipment (de-energised) that has been extended.
Manufacturers' guidance notes require a 28kV pressure test for commissioning the new tier. The technicians wanted not to perform it, due to...
Hi,
Does someone have reference to the appropriate formula for normalising IR test values to 20degC?
For reference we have extended an 11kV Metal-Clad Switchgear bus, and while happy with the test results on the extension, the test results on the coupled board are low compared to the factory...
Hi,
As is typical, civil contractors have screwed up requirements for conduits penetrating a concrete slab, for equipotential bonding cables. This is a wastewater treatment plant on an Industrial site.
I have proposed to allow the contractors to chase into the concrete slab and the cable will...
Hi All,
Recently on an MV design-build project I had an unscheduled design review with the cable installing team after change of personnel.
For all our MV cable installs we calculate the minimum bend radii, maximum pulling tension, sidewall pressure, expected tensions and pressures etc. to...
Hi All,
I have a current 11kV private network expansion project wherein my company is performing design & build works.
Separately a consultant has been contracted by the client to perform the Fault Study and develop the Protection Settings. They also produced the concept design for the...
Hi,
I've had a search through the forum but can't find something specifically applicable to my query.
I normally work in the design of LV works, but in this instance am involved in the design and build of a handful of 11/0.415kV distribution substations connected to an existing industrial...
