1Pole or 3 Pole DC Circuit Breaker Application
1Pole or 3 Pole DC Circuit Breaker Application
(OP)
I would like to inquire if it is a Code requirement to use 2 pole circuit breaker for 125Vdc, 2 wire system. The switchgear used 2Pole breakers while the panelboard used 1pole circuit breakers...does this matter?






RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
Overcurrent Device Required. A fuse or an overcurrent trip unit of a circuit breaker shall be connected in series with each ungrounded conductor.
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
A ground fault on an ungrounded DC control system will not operate any protection nor cause misoperation in a properly designed system (watch your control levels), and can be alarmed to allow one to go looking for the fault without having everything go to heck in the mean time.
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
Dc control power supplies should definitely be ungrounded for improved reliability.
RE: 1Pole or 3 Pole DC Circuit Breaker Application
Thank you very much
RE: 1Pole or 3 Pole DC Circuit Breaker Application
The other property of a grounded system (that one might want to avoid) is a ground fault that causes some unintentional system operation. Control circuitry is supposed to eliminate these by prohibiting switching of the grounded side of a relay coil, for example. But with complex systems, finding every possible sneak circuit can be difficult.
RE: 1Pole or 3 Pole DC Circuit Breaker Application
Substation DC supply will be ungrounded only.
I agree with it 100%.
Storngly recommend DC control system with UV/OV+Ripple+Isolation monitoring.
Best Regards.
Slava
RE: 1Pole or 3 Pole DC Circuit Breaker Application
RE: 1Pole or 3 Pole DC Circuit Breaker Application
Actually strongly recommended only one DC monitoring per DC bus, in case of coupling of two busses start problem with isolation monitoring. I recommend ask a vendor, Bender for example.
Best Regards.
Slava
RE: 1Pole or 3 Pole DC Circuit Breaker Application
In the US, Solar PV arrays that have circuit breakers or fused switches for protection are only allowed to break the positive pole, never the negative, and the negative must always be grounded.
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RE: 1Pole or 3 Pole DC Circuit Breaker Application
It did not work well with the UPS negative ground (SEL UPS has a negative ground).
RE: 1Pole or 3 Pole DC Circuit Breaker Application
Photovoltaic power systems shall be permitted to operate with ungrounded photovoltaic source and output circuits where the system complies with 690.35(A) through (G).
I don't see where it is forbidden.
RE: 1Pole or 3 Pole DC Circuit Breaker Application