tailieunhanh - Industrial Control Wiring Guide 2E Episode 10

Tham khảo tài liệu 'industrial control wiring guide 2e episode 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 8. COMPONENTS ACTIVE . Auxiliary contacts Auxiliary contacts can be fitted to the top or to the sides of most contactors. . Interlocks Two contactors may be interlocked so that only one will operate at any time. This may be used for instance when the two contactors switch a motor in different directions. The actual detail of fitting these interlocks differs but in general the interlock unit is fitted between the two contactors. For exact methods of fitting read the instruction leaflet which will accompany the contactor. Moving spigots on either side engage in slots on each contactor. If the contactors are fitted to a DIN rail they must also be clipped together using the spring clips which will be supplied with the interlock kit. If they are fitted to the chassis then they are usually mounted to a plate before being fixed to the chassis. The contactors must not be able to move relative to each other on their mounting otherwise the interlock will fall out. Once fitted check that they will only operate one at a time by pushing down the contactor armatures. 84 8. COMPONENTS ACTIVE Example of protective unil for filling to a contactor . Protective units Further add-on parts to a contactor-type control system include overload prevention devices. A protection unit may have to be fitted . a thermal overload unit. These have three pin connectors which engage into the contactor s screw clamps. The overload unit has a changeover contact unit in addition to the three protected connections. Most also have a clip to secure them to the base of the contactor. 85 8. COMPONENTS ACTIVE . Labelling Coils are marked alphanumerically . A1 A2. Odd numbers - incoming supply terminal. Even numbers - outgoing terminal. Main contacts are marked with single numbers Odd numbers - incoming supply terminal. Next even number - outgoing terminal. Auxiliary contacts are marked with two numbers First number - sequential. Second number - functional. For example a set of .