1、 Regulations on cable color

National standard: yellow, green, red and blue represent a, B, C and N respectively.
European standards: red (L1), yellow / white (L2), blue (L3), black (neutral line), green / yellow (ground line).
Future standard colors: Brown (L1), black (L2), gray (L3), blue (center line), green / yellow (ground line).
Phase a of AC three-phase circuit: yellow; Phase B: green; Phase C: red; Neutral line or neutral line, light blue; Grounding wire: yellow and green.
AC circuit connected by double core conductor or twisted pair: red and black parallel.
Positive pole of DC circuit: Brown; Negative electrode: blue;
Identification allowed for Conductor: black, brown, red, orange, yellow, green, blue, purple, gray, white, pink, cyan
2、 Measurement of cable color
With the continuous development, the requirement of cable color is higher and higher, and the judgment of naked eye can not meet the demand. For exported cable products, the color requirements are more strict.
Δ E refers to the standard deviation in L * a * b * color space, and its size can directly represent the perception gap of human eyes for object color. As an important indicator of color difference, the color difference meter can accurately measure the color difference of cable color. The color difference meter can measure the lab value of the color of the optical cable and calculate the difference with the standard sample Δ E. The values of △ L, △ A and △ B.
Δ E represents the total color difference,
△ L + indicates partial white, △ L - indicates partial black,
△ a + indicates partial red, △ a - indicates partial green,
△ B + indicates yellowish and △ B - indicates bluish
Firstly, the reference sample is measured to obtain the color information of the reference sample (the values of L, a and b); Then measure the measured sample to obtain the color information of the measured sample (the values of L, a and b). The color difference value of the cable color can be measured according to the color difference formula.
Instrument settable Δ The difference of E is 1. When the color difference of the produced cable is greater than 1, the instrument will remind that it is unqualified.