{"id":4250,"date":"2026-09-26T00:00:00","date_gmt":"2026-09-26T00:00:00","guid":{"rendered":"https:\/\/chac-electric.com\/?p=4250"},"modified":"2026-10-19T03:37:32","modified_gmt":"2026-10-19T03:37:32","slug":"cac-loai-cau-dao-dc","status":"publish","type":"post","link":"https:\/\/chac-electric.com\/vi\/blog\/dc-circuit-breaker-types\/","title":{"rendered":"C\u00e1c lo\u1ea1i c\u1ea7u dao DC"},"content":{"rendered":"

The main C\u00e1c lo\u1ea1i c\u1ea7u dao DC<\/strong> used in low-voltage projects include miniature and molded-case breakers with declared DC ratings, alongside specialist designs for particular applications. The useful classification is not just the enclosure size. Identify the energy source, maximum voltage, current direction, prospective fault current and approved pole arrangement first. A device suited to one PV string is not automatically suitable for a battery bus at the same nominal voltage.<\/p>\n

\"C\u00e1c<\/p>\n

Separate breaker construction from application approval<\/h2>\n

DC MCBs are often considered for compact branch circuits; DC-rated MCCBs may offer different frame sizes, trip units and accessory options. Those are family tendencies, not guaranteed current or breaking-capacity boundaries. Read the offered model\u2019s ratings. Some devices have fixed settings and others have adjustable protection, so the letters alone do not tell you what can be configured.<\/p>\n

An isolating switch is a different product function. It may provide a means of disconnection without automatic overcurrent protection. Likewise, a remote-opening accessory does not turn an unsuitable protective device into an approved DC breaker. Write the required interruption and isolation duties separately in the equipment schedule.<\/p>\n

Treat PV and battery fault sources differently<\/h2>\n

For a PV circuit, establish the maximum system voltage under the project\u2019s temperature assumptions, string arrangement and possible reverse-current paths. For a battery circuit, establish the battery configuration, prospective fault contribution and the conditions declared for the protective device. An inverter\u2019s normal operating current does not establish the fault duty supplied by a battery.<\/p>\n

Ph\u1ea7n battery circuit protection<\/strong> review should include charging, discharging, isolation and fault states. A device that interrupts the normal discharge direction may not be suitable for reverse energy flow or every fault location. Obtain application-specific manufacturer evidence rather than treating a solar-labelled breaker as a universal DC component.<\/p>\n

Distinguish polarity from line and load direction<\/h2>\n

A polarity marking, a line\/load instruction and a declaration of bidirectional suitability are related but different pieces of information. Schneider Electric\u2019s C60H-DC FAQ states that the marked polarity must be respected and that the range should not be used where momentary current reversal can occur. That is a model-specific restriction; it should not be generalized to every DC breaker.<\/p>\n

Ask the supplier to identify permitted current direction for normal operation and interruption. If a storage system can charge and discharge through the same device, that operating mode must be covered explicitly. Do not infer bidirectional fault interruption from a non-polarized product label alone.<\/p>\n

\"C\u00e1c<\/p>\n

Read voltage and pole arrangement as one rating<\/h2>\n

Some DC devices use a manufacturer-specified series pole connection to meet a declared voltage. That connection must follow the exact diagram. Do not create a higher voltage rating by multiplying poles, improvise links or parallel poles to increase the current rating. Earthing arrangements and the fault path can affect how voltage is distributed across the interrupting poles.<\/p>\n

CHAC PXB6DC-63 DC miniature circuit breaker<\/a> v\u00e0 MCCB product range<\/a> provide starting points for a model enquiry. Confirm which offered device is documented for the actual DC application; a general MCCB family listing does not prove a DC rating.<\/p>\n

Keep the selection record useful for future replacement<\/h2>\n

Record the DC voltage range, pole wiring, polarity, current-direction limits, fault-current assumptions, terminal requirements and approved accessories. Include the exact catalogue number and drawing revision. This prevents a later replacement from being selected only because it fits the rail or has the same ampere marking.<\/p>\n

For the physical reason behind the different ratings, see the AC MCB versus DC MCB comparison<\/a>. Keep DC breaking capacity<\/strong> tied to the specified voltage and test conditions rather than importing an AC kA figure into a DC schedule.<\/p>\n

Which DC selection question changes with the source?<\/h2>\n\n\n\n\n\n\n\n\n
Source or operating condition<\/th>\nEvidence to obtain<\/th>\nUnsafe shortcut<\/th>\n<\/tr>\n<\/thead>\n
PV strings<\/td>\nMaximum voltage and reverse-current conditions<\/td>\nUsing nominal voltage alone<\/td>\n<\/tr>\n
Battery bus<\/td>\nFault contribution and interruption capability<\/td>\nSizing from normal inverter current<\/td>\n<\/tr>\n
Bidirectional storage<\/td>\nDeclared current-direction suitability<\/td>\nAssuming non-polarized means every duty<\/td>\n<\/tr>\n
Series-connected poles<\/td>\nExact manufacturer connection diagram<\/td>\nMultiplying an individual pole voltage<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
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C\u00e1c c\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/h2>\n

C\u00f3 th\u1ec3 s\u1eed d\u1ee5ng b\u1ed9 ng\u1eaft pha AC cho d\u00f2ng \u0111i\u1ec7n DC kh\u00f4ng?<\/h3>\n

Ch\u1ec9 khi nh\u00e0 s\u1ea3n xu\u1ea5t \u0111\u01b0a ra ch\u1ec9 s\u1ed1 \u0111\u1ecbnh m\u1ee9c cho \u0111i\u1ec7n \u00e1p, d\u00f2ng \u0111i\u1ec7n v\u00e0 c\u1ea5u tr\u00fac c\u1ef1c theo y\u00eau c\u1ea7u th\u00ec m\u1edbi \u0111\u01b0\u1ee3c coi l\u00e0 ph\u00f9 h\u1ee3p. Ch\u1ec9 s\u1ed1 \u0111\u1ecbnh m\u1ee9c ch\u1ec9 d\u00f9ng cho d\u00f2ng \u0111i\u1ec7n xoay chi\u1ec1u l\u00e0 kh\u00f4ng \u0111\u1ee7 v\u00ec quy tr\u00ecnh ti\u00eau di\u1ec7t tia s\u00e9t \u1edf d\u00f2ng \u0111i\u1ec7n xoay chi\u1ec1u l\u00e0 kh\u00e1c nhau.<\/p>\n

Does polarity matter on a DC circuit breaker?<\/h3>\n

It matters whenever the model has polarity or current-direction restrictions. Follow its markings and approved diagram. For a bidirectional battery circuit, obtain explicit confirmation that charging, discharging and relevant fault conditions are covered.<\/p>\n

M\u1ed9t nh\u00e0 thi\u1ebft k\u1ebf h\u1ec7 th\u1ed1ng PV n\u00ean ki\u1ec3m tra nh\u1eefng g\u00ec?<\/h3>\n

Ki\u1ec3m tra \u0111i\u1ec7n \u00e1p kh\u00f4ng t\u1ea3i t\u1ed1i \u0111a \u1edf nhi\u1ec7t \u0111\u1ed9 th\u1ea5p nh\u1ea5t, d\u00f2ng \u0111i\u1ec7n ng\u1eafn m\u1ea1ch, \u0111\u01b0\u1eddng d\u1eabn d\u00f2ng ng\u01b0\u1ee3c, nh\u00f3m d\u00e2y v\u00e0 hi\u1ec7u su\u1ea5t ng\u1eaft \u0111i\u1ec7n DC c\u1ee7a c\u1ea7u b\u1ea3o v\u1ec7.<\/p>\n

C\u00e1c c\u1ea7u b\u1ea3o v\u1ec7 DC c\u00f3 ph\u00f9 h\u1ee3p v\u1edbi pin kh\u00f4ng?<\/h3>\n

M\u1ed9t s\u1ed1 c\u00f3 th\u1ec3, nh\u01b0ng n\u0103ng l\u01b0\u1ee3ng do l\u1ed7i pin c\u00f3 th\u1ec3 v\u01b0\u1ee3t qu\u00e1 kh\u1ea3 n\u0103ng c\u1ee7a b\u1ed9 ng\u1eaft nh\u1ecf. X\u00e1c nh\u1eadn th\u00f4ng s\u1ed1 d\u00f2ng \u0111i\u1ec7n d\u1ef1 ki\u1ebfn, h\u00e0nh vi gi\u1edbi h\u1ea1n d\u00f2ng \u0111i\u1ec7n v\u00e0 d\u1eef li\u1ec7u \u1ee9ng d\u1ee5ng c\u1ee7a nh\u00e0 s\u1ea3n xu\u1ea5t.<\/p>\n

Should a DC switch be on the positive or negative conductor?<\/h3>\n

The grounding arrangement, required isolation function and manufacturer diagram decide which conductors must be switched. There is no universal positive-only or negative-only answer. A protective breaker and a disconnect must each satisfy their declared function.<\/p>\n<\/section>\n

Tham kh\u1ea3o<\/h2>\n