Dear all,
I'm checking a quote for a 25 kV Disconnector Switch and I noticed that in the attached circuit diagram the manufacturer uses 230 V AC (Europe) for all circuits, namely for the Control box auxiliaries (heating, light bulb, socket), the control circuit, the motor circuit and the...
Dear Sirs,
I am trying to build a model of a DC Traction Power System, composed of 10 Traction Substations (TSS) feeding a third rail, also known as conductor rail, system (750 V DC).
The main objective is to build a representative model that will confirm the points where the max/min di/dt...
Dear Sirs,
We have a MV switchboard consisting of three CB's:
1) one connected to the 20 kV grid,
2) the second feeding a 3.3 MVA 3-winding transformer and
3) the third feeding the substation auxiliaries 50 kVA 2-winding transformer.
We are experiencing several nuisance trips of the...
Hello everybody,
I had to work on an incident in a Traction Substation where a Hermetically sealed Oil Immersed Transformer, aka corrugated tank completely filled without conservator, tripped due to low oil level after shut down (in reality it did not trip, it just could not be brought back in...
Dear all,
In the IEC world, every cable designed for a voltage level greater than 1 kV shall have a metallic layer surrounding the core(s), par. 7.3 of IEC 60502-1.
With regard to safety of personnel, the above requirement ensures that the outer sheath of the cable will be safe to touch...
Dear all,
In an attempt to install some THHN cables we damaged two of our cable stripping tools.
These tools were previously succesfully used for similar works on building cables with thermoplastic PVC insulation rated for 70 deg Celsius.
Αs the root cause of the tools damage, apart from bad...
Hello everyone,
I came across the attached specification for MV power cables used in FPSO applications.
My experience is limited to the onshore industry and I can not find the use of the 6 ground wires located in the interstices between the 3 MV shielded power cores.
A large fault current...
Dear sirs,
I am currently working on a case of connecting an island (300 m from the coast) with the LV distribution system.
Two (for redudancy reasons) 3-core PILC/SWA lead sheathed cables will depart from the secondary of a distribution transformer (wye connection with the common point...
Hello everyone,
A number of cables of the type described below have been installed in 600 meter long 3-phase circuits.
Bundled MV cable consisting of three single cores each with aluminium conductor, XLPE insulated and laid up in bundled formation with a semiconducting tape(water...
Hello to everyone!
Due to incorrect parameters setting during the sheathing/jacketing process of a medium voltage, a big part of the produced cable has a total diameter exceeding the one originally stated to the end user by nearly 10% (67 mm compared to 60 mm). As if that wasn't enough, the...
Hello to everyone reading this!
My excel spreadsheet contains a cell with a variable value used in two formulas.
Both of these formulas should have values less than or equal to predetermined numbers, a different number for each formula.
Nevertheless, I must calculate the minimum number...
Hello!!
While I was working on some ampacity calculations, concerning several parallel circuits of distribution cables laid in a concrete ductbank,
I wondered whether there is a chance that the high temperature point of the cable routing lies in the entry point to the Substation.
It is common...
Hello to everyone,
In our Steam Turbine Seal Steam System we have the main control valve which opens at start up, run down and low load operation.
We also have a bypass manual valve in parallel with the control valve, in case the control valve fails.
The bypass valve is isolated during...
Hello everyone,
This is my first post but I have been reading Eng tips forums for about a year. I really appreciate the knowledge and information this forum provides to young engineers and I believe that a lot of the contributors here serve as an excellent example for continuous personal...
