Juffy
Electrical
- Apr 5, 2023
- 2
Hi everyone! My first post here. I hope I can take some of your opinion regarding my concern.
A newly constructed industrial factory will be supplied by a 1.5 MVA transformer and is metered in the primary. The utility will erect a new 34.5kV overhead electrical facility to supply this factory. In other words, that primary line will solely serve the said factory.
My task is to source out a Load Break Switch that fits the system requirements. As of now, I'm looking between LBS 1 and LBS 2. Here are their specifications:
LBS 1
LBS 2
Assuming full load, the primary current would only be 1.5MVA/(sqrt3*34.5kV) = 25.1 Amperes.
Am I right if I say that [1] since the load interrupting rating of both LBS is greater than 25.1 A (630 A and 600 A at 34.5 kV, respectively), either of these LBS can safely break a fully loaded 1.5 MVA transformer (of course under normal conditions)? I know that there are other ratings needed to be considered as well before I can finally select one LBS over the other. But if we solely focus on the interrupting rating, and assuming that LBS 1 is little cheaper than LBS 2,do you agree that [2] the LBS 1 is better than the LBS 2?
Here in our area, LBS 2 is commonly installed by contractors for 34.5 kV primary metered projects. If LBS 1 is indeed better than LBS 2, I will have an impression that lot of contractors in our area might not know LBS 2 exists. So, I'm afraid I'm going against the grain in this situation. Your opinions are highly appreciated and will give me encouragement.
Thank you!
A newly constructed industrial factory will be supplied by a 1.5 MVA transformer and is metered in the primary. The utility will erect a new 34.5kV overhead electrical facility to supply this factory. In other words, that primary line will solely serve the said factory.
My task is to source out a Load Break Switch that fits the system requirements. As of now, I'm looking between LBS 1 and LBS 2. Here are their specifications:

LBS 1

LBS 2
Assuming full load, the primary current would only be 1.5MVA/(sqrt3*34.5kV) = 25.1 Amperes.
Am I right if I say that [1] since the load interrupting rating of both LBS is greater than 25.1 A (630 A and 600 A at 34.5 kV, respectively), either of these LBS can safely break a fully loaded 1.5 MVA transformer (of course under normal conditions)? I know that there are other ratings needed to be considered as well before I can finally select one LBS over the other. But if we solely focus on the interrupting rating, and assuming that LBS 1 is little cheaper than LBS 2,do you agree that [2] the LBS 1 is better than the LBS 2?
Here in our area, LBS 2 is commonly installed by contractors for 34.5 kV primary metered projects. If LBS 1 is indeed better than LBS 2, I will have an impression that lot of contractors in our area might not know LBS 2 exists. So, I'm afraid I'm going against the grain in this situation. Your opinions are highly appreciated and will give me encouragement.
Thank you!