{"id":4235,"date":"2026-09-24T00:00:00","date_gmt":"2026-09-24T00:00:00","guid":{"rendered":"https:\/\/chac-electric.com\/?p=4235"},"modified":"2026-10-19T03:35:42","modified_gmt":"2026-10-19T03:35:42","slug":"ky-hieu-cua-mcb","status":"publish","type":"post","link":"https:\/\/chac-electric.com\/vi\/blog\/symbol-for-mcb\/","title":{"rendered":"K\u00fd hi\u1ec7u c\u1ee7a MCB"},"content":{"rendered":"

An MCB symbol<\/strong> identifies a miniature circuit breaker on an electrical drawing. It does not, by itself, tell an installer the current rating, trip curve, number of protected poles or approved replacement. Read the graphic alongside the drawing legend and device schedule. That combination is more useful than copying an isolated icon from an image search, particularly when a project uses both single-line and detailed wiring drawings.<\/p>\n

\"Bi\u1ec3u<\/p>\n

Start with the drawing legend and symbol library<\/h2>\n

Check which drafting convention the project uses before interpreting the symbol. IEC-based and North American drawings can represent breakers differently, and CAD libraries may simplify the same function in different views. Autodesk\u2019s IEC-60617 library, for example, distinguishes first-pole and additional-pole circuit-breaker symbols as well as one-line components. This is a reason to use the approved library, rather than a reason to treat every similar-looking graphic as interchangeable.<\/p>\n

A breaker, fuse and isolating switch can all interrupt a circuit, but they are different devices. Confirm that the selected symbol communicates automatic overcurrent protection. If the drawing is too compressed to show every function, put the missing information in the schedule and reference it clearly from the device tag.<\/p>\n

Show pole count without drawing a different protection function<\/h2>\n

On a single-line diagram<\/strong>, one drawn line can represent a multiphase circuit. It does not mean that the installed breaker has one pole. Show the required pole arrangement through the project\u2019s notation and schedule, and identify whether the neutral is continuous, switched or protected. A 1P+N device should not silently become a two-protected-pole device when the drawing is simplified.<\/p>\n

Common trip and mechanical linkage also need clear treatment. A handle drawn across several poles does not prove that three independent breakers provide the required common-trip function. Check the actual device construction and use the library\u2019s approved representation of the relationship.<\/p>\n

Keep the device tag consistent from diagram to panel<\/h2>\n

Give each breaker a unique project tag and use it consistently in the one-line diagram, wiring drawing, panel layout and bill of materials. A label such as QF1 is only an identifier chosen under the project convention; it is not a product approval or a universal substitute for a catalogue number. The schedule should connect that tag to the exact device and circuit.<\/p>\n

For a product review, the B\u1ed9 ng\u1eaft m\u1ea1ch c\u1ee1 nh\u1ecf CQB2-63<\/a> page and CHAC\u2019s D\u1ea3i s\u1ea3n ph\u1ea9m MCB<\/a> provide starting points for model information. Transfer only the verified ratings and configuration of the selected variant into the drawing. A generic family photograph cannot establish the pole arrangement of an ordered device.<\/p>\n

\"K\u00fd<\/p>\n

Separate handle markings from the circuit\u2019s safe state<\/h2>\n

ON, OFF and trip indications describe aspects of the device\u2019s operation. They do not prove that the whole circuit is de-energized: another supply, a UPS or a connected energy source may still be present. A drawing should identify relevant sources and isolation boundaries instead of relying on a handle-position graphic as a safety instruction.<\/p>\n

S\u1eed d\u1ee5ng circuit breaker schedule<\/strong> to record the verification information the installer needs. That includes the supply arrangement, device reference, ratings, conductor details and any special neutral or isolation requirement. Keep the safety procedure in the installation documentation rather than trying to encode it in one tiny symbol.<\/p>\n

Review revisions before releasing the drawing<\/h2>\n

A useful final check follows one tag through all the documents. Does the pole count match the bill of materials? Does the curve match the selected breaker? Does the diagram show every source that can energize the circuit? Are retired symbols and obsolete catalogue numbers still present in copied blocks? These checks catch practical errors that a visually tidy drawing can hide.<\/p>\n

For the neutral and pole decision behind the graphic, see how DPN and 1P+N breakers are identified<\/a>. Keep the approved drawing revision with the panel so a later replacement can be checked against the original design, rather than selected by appearance.<\/p>\n

What belongs beside the symbol or in its schedule?<\/h2>\n\n\n\n\n\n\n\n\n
Item<\/th>\nWhat to record<\/th>\nT\u1ea1i sao \u0111i\u1ec1u \u0111\u00f3 l\u1ea1i quan tr\u1ecdng<\/th>\n<\/tr>\n<\/thead>\n
Device tag<\/td>\nUnique drawing reference and catalogue number<\/td>\nConnects the graphic to the installed device<\/td>\n<\/tr>\n
S\u1eafp x\u1ebfp c\u1ed9t<\/td>\nProtected poles, switched neutral and common trip<\/td>\nPrevents an incorrect substitution<\/td>\n<\/tr>\n
Electrical ratings<\/td>\nCurrent, voltage, curve and breaking capacity<\/td>\nSupports the circuit design review<\/td>\n<\/tr>\n
Revision<\/td>\nApproved drawing and schedule revision<\/td>\nKeeps later replacements traceable<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

C\u00e1c c\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/h2>\n

What is the symbol for an MCB?<\/h3>\n

It is the approved circuit-breaker graphic used by the drawing\u2019s symbol library, identifying automatic overcurrent interruption. Read it with the legend and device schedule; an icon alone does not establish current rating, pole construction or suitability.<\/p>\n

MCB n\u00ean xu\u1ea5t hi\u1ec7n nh\u01b0 th\u1ebf n\u00e0o tr\u00ean s\u01a1 \u0111\u1ed3 m\u1ed9t s\u1ee3i?<\/h3>\n

Hi\u1ec3n th\u1ecb thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 tr\u00ean m\u1ea1ch c\u1ea5p ngu\u1ed3n, x\u00e1c \u0111\u1ecbnh c\u00e1c c\u1ef1c v\u00e0 d\u00e1n nh\u00e3n v\u00e0o b\u1ea3ng bi\u1ec3u. Th\u00eam \u0111\u1ecbnh m\u1ee9c v\u00e0 \u0111\u01b0\u1eddng cong \u0111\u1eb7c t\u00ednh \u1edf nh\u1eefng n\u01a1i \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn ph\u1ed1i h\u1ee3p b\u1ea3o v\u1ec7.<\/p>\n

C\u00e1c k\u00fd hi\u1ec7u ON v\u00e0 OFF c\u00f3 thu\u1ed9c v\u1ec1 s\u01a1 \u0111\u1ed3 m\u1ea1ch \u0111i\u1ec7n kh\u00f4ng?<\/h3>\n

Ch\u00fang r\u1ea5t h\u1eefu \u00edch tr\u00ean b\u1ea3n v\u1ebd t\u1ee7 \u0111i\u1ec7n v\u00e0 s\u01a1 \u0111\u1ed3 \u0111i d\u00e2y, nh\u01b0ng s\u01a1 \u0111\u1ed3 m\u1ed9t s\u1ee3i c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng ch\u00fa th\u00edch tr\u1ea1ng th\u00e1i chuy\u1ec3n m\u1ea1ch thay th\u1ebf. Gi\u1eef cho c\u00e1ch th\u1ec3 hi\u1ec7n \u0111\u01b0\u1ee3c nh\u1ea5t qu\u00e1n gi\u1eefa c\u00e1c t\u00e0i li\u1ec7u.<\/p>\n

T\u1ea1i sao ph\u1ea3i th\u1ec3 hi\u1ec7n \u0111\u01b0\u1eddng cong tr\u00ean b\u1ea3n v\u1ebd?<\/h3>\n

\u0110\u01b0\u1eddng cong gi\u00fap ng\u01b0\u1eddi \u0111\u00e1nh gi\u00e1 ki\u1ec3m tra c\u00e1c gi\u1ea3 \u0111\u1ecbnh v\u1ec1 kh\u1ea3 n\u0103ng ph\u00e2n bi\u1ec7t v\u00e0 d\u00f2ng kh\u1edfi \u0111\u1ed9ng. N\u00f3 ph\u1ea3i ph\u00f9 h\u1ee3p v\u1edbi m\u00f4 h\u00ecnh \u0111\u00e3 ch\u1ecdn v\u00e0 nghi\u00ean c\u1ee9u ph\u1ed1i h\u1ee3p.<\/p>\n

What are IEC standard symbols?<\/h3>\n

They are standardized graphical representations used to communicate electrical functions consistently. IEC 60617 covers diagram symbols. The project must still state which library and drawing convention it uses, and the device schedule supplies model-specific information.<\/p>\n<\/section>\n

Tham kh\u1ea3o<\/h2>\n