HOW MANY METERS NEEDED?
HOW MANY METERS NEEDED?
(OP)
I have situation where I have a switchgear fed by four 750 kva transformers from the Utility. Since switch gear is nearly 40 years old with many loads that are unknown.
I have requested a consultant to meter the current loading on switchgear in order to ensure that the switch gear can take any additional.
I felt that in order to measure the current loading of this SW I need only one meter by which I can take reading of the main bus from which all the loads are fed. However I was told by a higher authority, that I need to use three more meters to measure the actual loading on this SW. This is some thing, I am not sure I agree as I feel that only one meter is adequate to measure the actual loading on the SW. I assume since the SW is fed by four network transformers, I was told I need 4 meters to measure the loading!
In my opinion no matter how many transformers feed the SW, finally every thing ends up in the main bus, so you need only one meter to measure the loading on this SW.
If anyone thinks otherwise please let me know why. Thank you in advance
I have requested a consultant to meter the current loading on switchgear in order to ensure that the switch gear can take any additional.
I felt that in order to measure the current loading of this SW I need only one meter by which I can take reading of the main bus from which all the loads are fed. However I was told by a higher authority, that I need to use three more meters to measure the actual loading on this SW. This is some thing, I am not sure I agree as I feel that only one meter is adequate to measure the actual loading on the SW. I assume since the SW is fed by four network transformers, I was told I need 4 meters to measure the loading!
In my opinion no matter how many transformers feed the SW, finally every thing ends up in the main bus, so you need only one meter to measure the loading on this SW.
If anyone thinks otherwise please let me know why. Thank you in advance






RE: HOW MANY METERS NEEDED?
conductors are connected to a common bus, it seems like it would be difficult to meter all 4 with one set of Ct's but I do not know how the physical connections are made.
RE: HOW MANY METERS NEEDED?
RE: HOW MANY METERS NEEDED?
You must provide us with a little more information please.
Thank you
respectfully
RE: HOW MANY METERS NEEDED?
RE: HOW MANY METERS NEEDED?
T1 T2 T3 T4
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L1 L2 L3 L4
If, however, you have a configuration as shown here, you will need 4 instruments, since there is no one place on the bus where all of the load current will pass through.
T1 T2 T3 T4
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L1 L2 L3 L4
RE: HOW MANY METERS NEEDED?
You might get by with one set of CTs on the high side but it depends on the physical configuration of the installation.
In theory you can do it with one set on the secondary. In practice you may not be able to get all the scondaries though one set of CTs.
From the diagram above I would vote for four CTs and use somthing like these.
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I have used the flexible current sensors and there have been places where it's hard to get them around all the secondary conductors of a 2,500 Kva transformer.
I don't think you have a theory problem, it's a practical problem.