I am trying to calcualte how much fault current this transformer can give. The image might be hard to read but it is 3-1phase 167kVA transformers. from the photo it looks like they are using one input winding and are tapping the windings of each center to get the 240V. never saw this before...
I have a situation where resistors must engage to correct a problem. The Vendor has bought some off the shelf NON UL Listed resisotrs and threw them in a hoffman box UL Listed.
My understanding was everything must be UL Listed.
This is a project in USA. I am asking the AHJ, but in the...
Thanks for the comments!
The testing of the PT invovled grounding and turns ratio test. The system works when on utility...which has the team convinced the PT's are working correctly...
The 500V is being seen at the HMI. The voltage is rising from the generator building to the main service...
Pictures is worth a thousand words.
PT1 is open delta grounded on the secondary, PT2 is grounded wye. During normal operation with the utility supplying the facility and the generator breakers NO PT1 and PT2 read the exact same. The voltages all show up as normal and within tolerance.
When...
Situation: 12kV switchgear fed from utility. This service entrance switchgear has a 12kV generator connect onto as well as one utility onto the bus and all new SEL-351 relays have been provided for the new incoming generator and utility breakers. All of the existing potential transformers are...
Would adding a transformer with nothing connected to it cancel out the capacitance in the cables??
How much load do you think we need to cancel out the capacitance?
10%...
thoughts?
Would adding a transformer to the circuit be enough inductance to lower the voltage? In anybodys opinion how much load would need to be added to lower the voltage??
10%-20%....
Thoughts?
Awesome. The more I learn the more I realize I dont' know S*$# [sadeyes]
Can this be hand calc'd or just way to complicated and software must be utilized? I have a difficult time when I do not grasp something and it slowly drives me insane. I will digest this over the next day or so and come...
Thanks for the replies.
collies99
The generators are solidly grounded
I believe there are no transformers connected to the system.
Everything is open but all the feeder breakers are closed that each feed a mile worth of 500kcmil conductors.
So when the gens were running the only load on the...
System: (2) 12kV, 2500MW Generators that parallel to a common bus and connect to the main switchgear and power some large loads. The system is a closed transition with the Utility. During normal operation only one utility is present.
I have attached a diagram of the electrical system.
The...
Also I believe IEEE 1547 requires wye-wye PT's which aid in directing fault direction.
Maybe I missed it by why would you still not use the 50/51 protective device on the mains? I guess the only thing it would protect would be the bussing between the mains and the feeder breakers and by the...
Thanks everybody for your comments.
MCF59s: thanks for your feedback. We are hitting the switch on this installation in a few months. I modled this using EMTP-ATP, but not to sure about the results because a lot of the really important system parameters are not currently known. I do feel a...
I am fixing a fuel cell design in San Diego...LOL
What are the advantages and disadvantages?
On site power production is pretty cool especially if you have a parasitic load. Disadvantages are meeting IEEE 1547 and what do you do if there is no load...the fuel cell will take up to 8 hours to...
When forced to use this stuff, I like to wire up the door contacts to disengage the light arc flash detection to prevent photos, outside light from tripping/locking out your switchgear. I agree that a MV breaker takes 3 cycles for the new ones, so
odlandor, I believe the base is 100MVA, 12000V.
MLS1 - The solidly grounded transformer is on the 12kV distribution network along with all the cogens and the two other impedance grounded transformers. I agree that if the nuetral was grounded on the other side of the transformer then we would...
Thanks. I doubled checked the model and impedances for the transformers and they are in fact grounded through a 200A, 34.6 ohm resistor for each one, while the fuel cell transformer is solidly...
