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Hello, I am involved in a project where a 3-phase 25 MVAr shunt reactor is to be installed at 50 kV line voltage. The connection would be star. I have read that some manufacturers advice that shunt reactors below 72,5 kV should have isolated neutral and grounded neutral for voltages of 115 kV...

The noise records have been made for an unloaded transformer.

The system frequency is 50 Hz. The 500 Hz noise is coming from internal of the transformer from my opinion. There are no loose parts exterior causing resonance

I have performed a number of noise recordings for a 20 MVA 132/50 kV transformer, ONAN. As expected there is a 100 Hz component and multipla of this 100+n*100 Hz due to magnetostriction etc. However I detect a very huge 500 Hz noise component in the noise frequency spectrum. I have cross...

Grounding at the 2 end point are also just fine allrhough circulating screen current affects the AC-resistance to a much less extend compared with this problem. Waross are you able to make a equivalent circuit diagram which explains the principle of the problem with midsection earthed. Thank...

Hello I have performed measurements on a 50 kV, 3x1x1200 mm2 AL PEX cable with 96 mm2 CU screen. The cable system has a length at 6700 m. At the midpoint the screens are earthed to reduce screen voltage the system has earthed screen at both ends. Cables are laid in flat formation. A VLF test...

HelloGBTerpenhow Thank you so much. I am familiar with the energy dissipation formula. Do you by any chance have pages from ASHRAE chapter 16, adressing ventilation inlet area calculation. I am not an expert on HVAC since I am a power Engineer😉 BR. Hans-Henrik

Hello I need to calculate the necessary area (m2) of the inlet in a building where a heatloss of 24 kW is dissipated. There is a distance of 2,8 m between openings of inlet and outlet. There are two scenarios: - natural ventilation - forced ventilation I am looking for formulas or litterature...

Hello At the utility grid at 10 kV I have made a model of this for simulating touch voltage. When experiencing a 2-pole short circuit to ground the touch voltage exceed 3 kV related to ground potential because of the high short circuit current and the resistance to ground. Maximum (worst case)...

Hi Please refer to attached pdf. Can anyone tell me what is wrong considering my calculation of U2 potential when there is a single phase fault on HV in secondary substation. I am considering a TT-system with RE and RB not connected. IEC 60364-4-442 table 44.A1 says U2=U0, however I reach the...

Hello everyone IEC 61230 states to Apply a peak current factor of 2,5 for the peak sc. current. From grid study analysis of the utility grid the R/X short circuit ratio is close to zero. Thus the peak current factor theoretically reaches 2x sqrt(2)=2,83. I am a little confused as why IEC tends...

Nearly unloaded the voltages are well balanced at approximately 230 V

The imbalance of 8 V is not neccessarily a problem, but Seen from an Engineering perspective it is unsatisfying not being able to explain this. The customer is complaining about a low voltage of only 214 V in L1 with High load whilst it is 222 V in L3. Tapping up the substation trafo is a...

Waroos certainly has a point regarding various lighting technologies. However since harmonics are measured this has sort of been taken into consideration within the simulation. What about some sort of uneven distibuted capacitance tending to raise the voltage?

Hello At a horticulture with a lot of LED growth lamps we have made some measurements. See Fluke pictures below. I am not able to explain why L1 is dropping to 214 V and L3 is 8 V higher and 222 V. The load are approximately the same, 55-56 kW and 6-7 kVAr. Also the harmonics does not vary much...

Hello One of our clients have multiple 10/0,4 kV substations at the industrial area with Dyn- transformers. Now the client wishes to establish an earthing connection between the substations by mesns of 240 mm2 cable connection. In my opinion this is an advantage regarding overall safety...

Hi all, I am working at a electric utility company. We currently have complaints from a client claiming that the grid is subject to electrical disturbances. The problem of the client is that a number of industrial PCs suddenly shut down (in some case only 3 in other cases all 16 PCs at the...

This standard EN50160 applies among other to power quality more precisely voltage disturbances in public distribution systems. (Power quality is a common way of qouoting disturbances caused by either disturbances in voltage, current or both). In th meantime I have recieved the final report with...

Hello I am working in a utility company. One of our clients ives in one out of 20 townhouses. All houses have 6 kW PV´s 3-ph. installed. The problem is that the client is experiencing problems charging the electrical vehicle. From measurements we have concluded that the problem is caused by the...

Hello David Thank you very much for the answer. Are you able to make reference to an IEC, EN, etc. standard about the temperatures. Best Regards Hans-Henrik