For the convenience of installation, operation, and maintenance, all equipment connections in the secondary circuit must be numbered, referred to as the secondary circuit label. The label generally uses numbers or a combination of numbers and text, indicating the nature and purpose of the circuit.
Basic principles for labeling secondary circuits:
(1) All connecting wires between equipment that need to be connected through terminal blocks using control cables should be numbered according to the circuit numbering principle.
(2) Some devices installed on the top of the screen also need to be connected to the devices inside the screen through terminal strips. In this case, the top of the screen device can be considered as an external device, and the corresponding numbering should be given on its connecting line according to the circuit numbering principle.
(3) For clarity, different labeling methods are used for DC and AC circuits, and in AC and DC circuits, different digital symbols are assigned to different circuits. Therefore, in the secondary circuit wiring diagram, as long as the label is visible, the nature of this circuit can be known for easy maintenance and repair.
Electrical design circuit wire number rules:
1) Current circuit: a Line number rules: letters (one to two digits)+4+numbers (two to three digits), including line numbers with a trailing '. Examples: A411, A4111, HL411, HN411, ML411, MN411, A411'
2) Voltage circuit:
a. Line number rules: letters (one to two digits)+6 (or 7)+numbers (two to three digits), including line numbers with 'at the end. For example, A630, A660, EA630, YA630, UA630, WA630, EA630' and some special ones:
I (II) - A710, I (II) - B710, I (III) - A710,
UA640 (UA660), UB640 (UB660),
3) Control circuit: pure digits, one to four digits starting from 0 to 6, and one to two digits starting from 7 to 9.
Trip circuit: 33 (033), 133, 233.... Circuit number ending in 33;
Closing circuit: 03 (3), 103, 203... circuit number ending in 03;
Positive power circuit: 01 (1), 101, 201, 301... circuit number ending with 01;
Negative power circuit: 02 (2), 102, 202, 302... circuit numbers ending in 02; 4) Signal circuit: 7 (or 8, 9)+digital (two to three digits), F 7 (or F 8, F 9)+digital (two to three digits) (excluding 881-899).
Power circuit: 701, 702, 801, 802, 901, F701, F702, F801, F802, F901 5) Small busbar circuit:
DC: wire numbers starting with "+" and "-", for example:+KM, - KM
Communication: Line numbers starting with "~", such as~A,~B,~C6) Locking circuit: 881-899, which is an AC circuit.