No standard. The meaning of the first part of the characters is as follows:
Z series: general-purpose DC motors (such as Z2 Z3 Z4 and other series).
ZJ series: DC machine for precision machine tools.
ZT Series: Wide speed-regulating DC motors.
ZQ Series: DC Traction Motor.
ZH Series: Marine DC Motor.
ZA Series: Explosion-proof and Safety DC Motor.
ZKJ Series: DC Motor for Excavator.
ZZJ series: DC motors for metallurgical cranes.
Expanded Information:
Nameplates are divided into concave-convex and plane nameplates. The paint used to fill in the concave part of an ordinary concave-convex nameplate is nitro lacquer. The method of painting is to spray paint all the front of the nameplate, and then remove the paint from the font or pattern part, exposing the metal lettering or pattern lines. Higher grade intaglio nameplates are just coated with baking paint, or partially coated with color paint, or coated with transparent varnish.
It depends entirely on the requirements. Plane nameplate is mainly made of aluminum alloy material, the color on its surface is not paint, but through the anodic oxidation, dyed color, according to the different process methods, it can be a single color, or 2-3 colors. Flat nameplates have high decorative properties and are less expensive. Others have screen leakage printing nameplate, the color used is ink;.
Baidu Encyclopedia - Nameplates