General control circuit components required more significant number of contacts

Using relays, contactors and other control buttons on electrical motors or other electrical equipment on or off automatic control system, called the relay contactor system. It is widely used in machining control, power transmission and distribution system, elevator control, and air conditioning and refrigeration equipment control and so on. Because the system is by controlling the state of the contact element and that a logical relationship, it is generally required many components of the control circuit, a large number of contacts. This characteristic to the line maintenance caused great difficulties. I work in practice summed up a set method --- relay contactor control system functions chain  electri cenergy meter and troubleshooting chart column method. Are presented below for reference. Relay  circuit breakers system functions chain control system wiring diagram is a schematic representation, in accordance with component action sequence, indicating that the control circuit functions chain diagram. It clearly reflects the control lines and achieve functional correspondence between, helps to understand the working principle of control lines to help control the line maintenance and troubleshooting.