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MCB & Cable Size for 3 Phase Star (Wye) with Neutral

Hi, I'm trying to understand/figure out what MCB & Cable Size would be required for a 3 Phase 9kW Immersion Element wired in Star using Neutral? I have been a little confused by the results when using various online calculators. One example here: https://www.watlow.com/resources-and-support/engineering-tools/3phase-delta-wye-calculator

i.e. Using a Line Voltage of 400V equals a Phase & Line Current of 12.99A. Where as using a Phase Voltage of 230V equals a Phase & Line Current of 22.59A?

My questions are:

1. Are these calculations correct?

2. What Amperage MCB would be required?

3. Would the MCB required need to be 3P, 3P+N or 4P?

3. Would 1.5mm2 cable at a 6 meter run be adequate?

Thanks in advance for your feedback and help.

Parents

0 Nano Brewery over 4 years ago

Cheers. Very informative and helpful.

TicTag - I don't think it is user error?... The confusion I am having with the online calculator when using in 3-Phase Wye (Balanced Load) is:

1.

Entering a known PHASE VOLTAGE of 230V (I understand that this is correct?)

Entering a known Wattage of 9000W

Gives a PHASE CURRENT & LINE CURRENT result of 22.59A

Or a PHASE CURRENT & LINE CURRENT result of 7.53A if 3000W is entered (which I understand would be the Wattage per phase)

2.

Where as entering a known LINE VOLTAGE of 400V (Which I also understand to be correct?)

And entering a known Wattage of 9000W

Gives a PHASE CURRENT & LINE CURRENT result of 12.99A (Which I understand as correct as Phase Current = Line Current in Star)

Why would this be the case?

mapj1 - I understand that the 6 meter cable run to an Isolator will be 5 core SWA XLPE. Then a 2.5 meter cable run of 5 Core SY Cable from the Isolators to the Immersion Element which is installed into the side of a Stainless Tank/Vessel. Cable will be either clipped to tray or installed in trunking. Would this help in deciding Cable Size? It seems that 2.5mm2 is maybe the way to go?

What is TT earthed?

Cheers for your feedback/help!
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0 Nano Brewery over 4 years ago

Cheers. Very informative and helpful.

TicTag - I don't think it is user error?... The confusion I am having with the online calculator when using in 3-Phase Wye (Balanced Load) is:

1.

Entering a known PHASE VOLTAGE of 230V (I understand that this is correct?)

Entering a known Wattage of 9000W

Gives a PHASE CURRENT & LINE CURRENT result of 22.59A

Or a PHASE CURRENT & LINE CURRENT result of 7.53A if 3000W is entered (which I understand would be the Wattage per phase)

2.

Where as entering a known LINE VOLTAGE of 400V (Which I also understand to be correct?)

And entering a known Wattage of 9000W

Gives a PHASE CURRENT & LINE CURRENT result of 12.99A (Which I understand as correct as Phase Current = Line Current in Star)

Why would this be the case?

mapj1 - I understand that the 6 meter cable run to an Isolator will be 5 core SWA XLPE. Then a 2.5 meter cable run of 5 Core SY Cable from the Isolators to the Immersion Element which is installed into the side of a Stainless Tank/Vessel. Cable will be either clipped to tray or installed in trunking. Would this help in deciding Cable Size? It seems that 2.5mm2 is maybe the way to go?

What is TT earthed?

Cheers for your feedback/help!
Cancel
Vote Up 0 Vote Down

Cancel

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MCB & Cable Size for 3 Phase Star (Wye) with Neutral

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