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I want to install MCCB for 750Vdc supply in traction application (Light Rail Transit). After finding some 750Vdc MCCBs, I looked for 1000Vdc MCCBs. All the 1000Vdc MCCBs are intended for photovoltaic application. PV MCCB standard is UL 489B whereas the usual MCCB standard is UL 489.

  1. Why is MCCB 1000Vdc for PV?
  2. What is the difference between UL489 and UL489B?
  3. Is it okay to use the 1000Vdc PV MCCB for my 750Vdc traction application?
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  • \$\begingroup\$ PV strings of many panels in series can achieve DC voltages in the 500-1000V range - more in a few cases. | I have no formal knowledge of the specs or different usages but I'd expect the PV breakers to suit your use. I may be wrong :-). \$\endgroup\$
    – Russell McMahon
    Apr 20, 2017 at 8:30

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Why is MCCB 1000Vdc for PV?

That is a matter of opinion. For whatever reason UL determined there was a need to have a standard that specifically covers circuit breakers for PV applications.

What is the difference between UL489 and UL489B?

UL489 covers circuit breakers for general use with exceptions and supplemental requirements for specific uses covered in the standard. UL 489A covers circuit breakers for use in communications equipment. UL 489 B covers circuit breakers for PV systems.

Is it okay to use the 1000Vdc PV MCCB for my 750Vdc traction application?

No. Items intended for specific uses either by UL standard number designation or by manufacturer designation are not suitable for other uses.

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