FM1201 HollySys Module, Shanghai Sijian Intelligent Technology Co., Ltd. is engaged in technical development, technical consultation, technical transfer in the fields of intelligent technology, information technology, and automation technology, as well as the sales of electrical equipment, automation equipment, electronic products, communication products, and electromechanical products. Industrial automation products: PLC, DCS, sensors, frequency converters, encoders, relays, servo drives, soft starters, touch screens. Brands involved in the products include: Eurotherm, Schneider, Siemens, ABB, SICK, P+F, E+H, Yokogawa, Yamakawa, Mitsubishi, Emerson, Honeywell, FANUC, GE, Eaton Electrical, CT,
FM1201 HollySys Module, Selection of current and voltage relays When selecting overcurrent relays to protect small and medium-capacity DC motors and wound-rotor asynchronous motors, the rated current of the coil can generally be selected based on the motor's rated current. For motors that require frequent starting, considering the thermal effect of the starting current in the relay, a three-phase thermal relay with phase-failure protection should be used. Selection of time relays
For applications with low requirements, the relatively inexpensive JS7-A series air-damped time relay is generally chosen; for higher requirements, the JS11 series electric time relay should be selected. The method should be chosen according to the requirements of the control circuit. Coil voltage. The coil voltage should be selected based on the voltage of the control circuit. Selection of speed relays The type of speed relay is mainly selected based on the motor's rated speed. (1) Selection of input/output points
Blindly choosing a model with too many points can result in unnecessary waste.
First, determine the total number of I/O points required for the control system, then reserve a margin of 15–20% of the actual total points (to allow for system modifications, etc.) before determining the required number of PLC points.
Additionally, note that some high-density input point modules have restrictions on the number of simultaneously connected input points; generally, the number of simultaneously connected input points should not exceed 60% of the total input points. The driving capacity (A/point) of each PLC output point is also limited; for some PLCs, the output current per point varies with the applied load voltage. Generally, the allowable output current of a PLC decreases as the ambient temperature increases. These issues should be considered during selection.
PLC output points can be categorized into common-point, grouped, and isolated connection methods. Isolated output points can use different voltage types and levels among groups, but this type of PLC has a higher average cost per point. If output signals do not require isolation, then a PLC with one of the first two output methods should be selected.