低压控制-(英文).ppt

* Star-Delta starters are very applicable to Low starting Torque devices such as compressor - motors. Limits inrush to 33% Long acceleration time Requires special 6 lead motor Lowest cost of reduced voltage * 4 Contactors: Start, Run, Short, Transition Transition Resistors Mechanical interlock between Run Shorting Contactors Timer control * * * Primary Reactor, connect reactor in the stator circuit, start with reactor and bypass the reactor when running. Auto-transformer, connect auto-transformer in the power circuit, start with part voltage and run in full voltage. * Low, 200 - 600 volts Medium, 601 - 69,000 volts High, 115,000 - 230,000 volts Extra High, 345,000 - 1,100,000 volts * * Power Circuits Controls incoming power to motor (on/off) Overload protective equipment Short circuit protection equipment Control Circuits Controls power components switching motor * * * * Do not confuse overload protection with short circuit protection! * * * Pressure transducer Application: Suction pressure for super heat control and low pressure protection Discharge pressure for high pressure protection Oil pressure for oil differential pressure protection Type: Variable capacitive Semiconductor piezoresistive Select by pressure range and output type (0~5V or 4~20ma) CH530 pressure transducer Working Pressure Range: 0 to 475 Psig Power: 24 +/- 10% VDC, 20mA max. Communications, RS485 Physical Layer, 19.2 Kbit CT/PT on CH530 Application CT (current transformer) detects 3 phase currents of compressor motor, for motor overload, phase reverse, phase loss, current imbalance protection PT (potential transformer) detects line voltage of power supply, for over / under voltage protection 3CTs and 3PTs connect to starter module can provide power meter function on CH530 control platform CT and PT can convert high current and voltage value to small value for control. We usually use CT with 50:0.1, 100:0.1, 150:0.1,200:0.1 …., PT with 600:30 Wiring must pay atten