We have two fire pumps, one is electrical on main utility transformer, and the second is standby pump. This standby pump is diesel operated, so it is not connected to the generator.
Please see the revised attached diagram now. The changes are in red color.
I have now used all four poles of the...
Jghrist, Yes I meant neutral of 208V; and the 480-120/208V is primary connected delta.
I have attached the diagram here. Please have a look and let me know your comments. Thankshttp://files.engineering.com/getfile.aspx?folder=246f32f3-eda5-4912-b567-b05f35742440&file=ATS_Connection.pdf
Thanks Jghrist, a couple of more questions…
In both Fig 1 and Fig 4 of the above reference, the five wires (3-Phases+G+N) are going towards the load. But in our case the load is a downstream transformer which already has its own neutral. So how should I deal with this situation?
Also I...
Please refer to Fig 1 on page 1 of the following link: http://mercedeelectric.com/Documents/00585847.pdf
Here the Y point of the generator is neutral and it looks that it is connected to the Y point of the utility transformer. The transfer switch in this figure is 3-pole.
In our case we have a...
I have a three phase 4 wire panelboard (3-phase + neutral). This panelboard is about 150 feet from the transformer.
Is it required that the neutral wire has to come directly from the Y point of the transformer? Or can use the ground wire near the panelboard as a neutral?
In transformer, the Y point of the secondary is connected to ground. Can we connect the body of the transformer with the same Y-point (for equipment grounding)?
Also can we ground the generator in the same way as transformer (connect the Y point of generator to ground)?
Thanks 7anoter4. Another question comes to mind.
Why is it that the arc flash study is required for 480V MCC/switchgear, but is not required for a 480V panelboard?
If we put a terminal block in an enclosure, for example universal-enclosure of Schneider, then do we need to consider the short circuit rating of only of the terminal blocks, or short circuit rating of enclosures as well?
NEC 430.24 is for determining the size of the conductor that feeds multiple motors.
I want to size the breaker that will protect the conductor (the conductor that feeds multiple motors)
I need to size the circuit breaker for a 208V feeder that supplies power to three 5HP motors in parallel. Vendor will take care of the overload and short circuit protection of individual motors. I only have to size the thermal magnetic circuit breaker for the main feeder that supplies power to...
In continuation to my last post, actually the table at the following link:
http://www.electrical-design-tutor.com/transformersizing.html
Shows that 600A breaker can be used on the secondary protection of 150kVA transformer @ 208V (instead of 550A).
So can I use 600A breaker for secondary...
Just one more question.
If I put 550A breaker in a weather-proof junction-box for the secondary protection of 150kVA transformer; still the main-breaker in the downstream panelboard has to be 600A, because 550A breaker is not available as the main breaker of panelboard.
So is it acceptable...
Let me re-phrase what I said above:
1. Can the same circuit breaker be used as the secondary protection of an upstream transformer, and primary protection of a downstream transformer?
2. Can the rating of a breaker for secondary protection of a transformer be 110% of transformer full load...
I have couple of more questions.
The sequence of equipment is as below:
1. 300 kVA transformer with a secondary current of 360A@480V.
2. Transfer switch with a service entrance type circuit breaker of 400A@480V.
3. 150kVA transformer with a primary current of 180A@480V and secondary current...
I need some help in sizing the breakers of transformers. We have following equipment.
1. 300 kVA Utility Transformer (12.47kV – 480V). (There is a 460V fire pump motor on this utility transformer)
2. Then a 480V transfer switch
3. Then a 150 kVA transformer (480V-208V)
4. Then a 208V panelboard...
I have to specify electrical equipment (like panelboard, light fixtures, etc) in an airport-hangar. The hangar has walls and roof but the problem is that it has a very large door from which the planes will come in and go out. In addition to this large door, there are two small doors as well.
I...
Does anybody know how to connect a load-bank to a transfer-switch?
I understand that load-bank will be connected at the terminals of the transfer-switch and will be in parallel to generator. Please let me know comments...
