可编程控制答案（Programmable control answer）.doc

可编程控制答案（Programmable control answer） Problem 2 1. what are the commonly used electrical control system diagrams? Solution: the commonly used electrical system diagram includes 3 kinds: electrical principle diagram, electrical appliance arrangement diagram and installation wiring diagram. 2. sketch the principle of drawing electrical schematic diagram. Attention should be paid to the following principles: (1) graphic symbols and text symbols of various electronic components in the electrical principle diagram according to the corresponding national standard drawing and dimensioning, electrical components of the same function should draw together, but each part of the same appliances do not necessarily draw together. All electrical components layout separately according to the functions of drawing, such as main circuit, control circuit, lighting circuit, signal circuit and protection circuit, in accordance with the order of the layout from left to right, from top to bottom, and according to the order of action as soon as possible. (2) the electrical components, power lines and contacts in the electrical schematic drawings are all drawn up in accordance with the graphic symbols stipulated by the standard, and are marked with the written symbols stipulated by the national standards. The three-phase AC power supply is concentrated at the top of the map surface, and the phase sequence from top to bottom is L1, L2 and L3 respectively. The neutral line (N) and the protective grounding wire (PE) are placed below the L. The contact state of each component is drawn according to the condition that the electromagnetic coil is not energized or has no external force. Contact the graphic symbol is placed vertically, drawing on the left right close principle, namely, the normally open contact and the normally closed contact of the direction of the left to the right direction; draw horizontal press following the closure principle, which is normally open contact in the upward directio