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Power Meter Voltage input 1
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davidbeach
Electrical
Circuit breakers don't have primary and secondary sides. Generally the available voltages are used, where the currents come from is typically more important. The bus voltages are going to be there whether the breaker is open or not, but since the current goes to zero when the breaker opens, the resulting power calculation will be correct either way.
When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.
-- Douglas Hofstadter, Jan 1982
When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.
-- Douglas Hofstadter, Jan 1982
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David has addressed function.
There is also code and safety.
The fuses should be rated for the Available Short Circuit Current at the fuse location.
The fuses must be suitable and rated for "removal when live" and suitable for a disconnect device.
It may be possible to circumvent this by de-energizing the main feeder to the MCC or panel.
There may be an advantage to seeing the feeder voltage before closing the breaker.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
There is also code and safety.
The fuses should be rated for the Available Short Circuit Current at the fuse location.
The fuses must be suitable and rated for "removal when live" and suitable for a disconnect device.
It may be possible to circumvent this by de-energizing the main feeder to the MCC or panel.
There may be an advantage to seeing the feeder voltage before closing the breaker.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
Option B with CB open before connecting the power meter for safety reason. If you want to know if power is available, put an indicator lamp before the breaker.
Muthu
Muthu
"..#1. Option B with CB open before connecting the power meter for safety reason. #2. If you want to know if power is available, put an indicator lamp before the breaker".
1. The Power meter is permanently wired (not a hand-held instrument). Connection safety is irrelevant.
2. The existing circuit shows that there are fused incoming power indication lamps H1..H3, before the CB, which would indicate whether power is available.
3. Option-A has the advantage that it can read the LL, LN Voltages and Frequency of the incoming, with the CB open.
4. The existing circuit does not show any Voltage and Frequency meter. These meters are not required as it is wired per option-A, where V and Hz can be read from the Power meter, with the CB open.
Note: If the source is from site gen set, Voltage and Frequency readings are vital; before closing the CB, feeding to the load.
5. Conclusion: Option-A has a slight advantage over Option-B.
Che Kuan Yau (Singapore)
1. The Power meter is permanently wired (not a hand-held instrument). Connection safety is irrelevant.
2. The existing circuit shows that there are fused incoming power indication lamps H1..H3, before the CB, which would indicate whether power is available.
3. Option-A has the advantage that it can read the LL, LN Voltages and Frequency of the incoming, with the CB open.
4. The existing circuit does not show any Voltage and Frequency meter. These meters are not required as it is wired per option-A, where V and Hz can be read from the Power meter, with the CB open.
Note: If the source is from site gen set, Voltage and Frequency readings are vital; before closing the CB, feeding to the load.
5. Conclusion: Option-A has a slight advantage over Option-B.
Che Kuan Yau (Singapore)
davidbeach
Electrical
Option A also allows multiple meters to share the same voltage source. Maybe not such a big deal at 400V, but at higher voltages where VTs are required to provide the voltage to the meter, every VT is more money.
When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.
-- Douglas Hofstadter, Jan 1982
When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.
-- Douglas Hofstadter, Jan 1982
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