I recommend an explusion fuse at the overhead line origin rated about 2x full load current with an aditional current limiting fuse at the transformer location if pad mounted or aditional explusion fuse if transformer is ground mounted power transformer.
Fuse for transformer protection should...
NEC Article 250-121 to 250-125, which probably does not apply to the system described. See also Article 504 if in haradous atmosphes. Article 250-5a for grounding of systems less than 50 volts and Article 725 for remote-control and signaling circuits.
Grounding requirements are based on power...
In answer to your XLPE vs. EPR the answer is yes to EPR being worth the difference for 12kV and higher systems. It is primarrily because XLPE is more porone to corona and water damage in URD application reducing cable life.
I have seen some good design guides on this subject from REA. These...
There is a quick and easy spread sheet for fault calculations at mikeholt.com. This spread sheet is set up to detrermine AIC for service equipment. Get there by going to site map then to calculations.
Be warned this is a basic calculation that needs information to fill in the blanks and does...
It is not normal to break the neutal in a 4 wire system except in cases where the neutal must be disconnected to prevent ground fault tripping problems such as on a generator in a hospital and similiar enviroments. It is also acceptable to interrupt neutrals in certain branch circuits in...
You have to add the currents vectorally taking into account the current at 0 degrees, 90 degrees lagging and 90 degrees leading.
Why so much capitance on the low loads? This amount of capitance with out off setting lagging power factor may cause voltage increase that may cause system overvoltage.
The circuit brreaker will not protect the motor. A three overload heater arrangement will normally protect the motor when the overload heaters are sized at motor full load amps. The two overload heater arrangement will not protect the motor. I have had reasonable luck with a three phase loss...
My preference is to use the step-up step-down transformer arrangement fot the following reasons:
1. voltage drop during motor starting, about 6 time running curent, at low power factor starting conditions may not provide adequate torque to start the motors.
2. Transformers with taps provied some...
You are asking a question that goes to the heart of electrical design. DCP is correct in the information provided in the two post.
Low voltage power circuit breakers (LVPCB) are the older workhorse of the industry. They are fixed or drawout mounting, have an interrupting rating and a...
I have used the old Bussman programs. It calculates fault current, but not voltage drop. It is a good program if still available. It will handle more than one source and about 50 busses at medium and low vlotage.
Cutler Hammer had a graphics program that calculated fault current and voltage...
Yes, probably.
Your description indicates a 480-120/240 volt transformer connection. If this is correct and you need both 120 and 240 volts then the coils must be connected togther to form a neutral connection, this is typically x2 & x3. Power one officew from x1 to neutral and one office from...
Thanks to busbar and marke for their responses. A review of the suggested thread did not provide info needed.
The secondary motor nameplate info, 2000 volts and 1350 amps, indicates 4,671Kva will go into the liquid rheostat solution.This does not seem a reasonable value for the heat to be...
We have a three stage liquid rheostat connected to a large medium voltage wound rotor motor and we are trying to determine the power (or heat) induced into the solution for the rheostar. This heat must be removed by a cooler on hot days in the south and this heat transfewr is the concern. The...
