變頻器控制方式特點:
其特點是控制電路結構簡單、成本較低,機械特性硬度也較好,能夠滿足一般傳動的平滑調(diào)速要求,已在產(chǎn)業(yè)的各個域得到廣泛應用。但是,這種控制方式在低頻時,由于輸出電壓較低,轉(zhuǎn)矩受定子電阻壓降的影響比較顯著,使輸出大轉(zhuǎn)矩減小。另外,其機械特性終究沒有直流電動機硬,動態(tài)轉(zhuǎn)矩能力和靜態(tài)調(diào)速性能都還不盡如人意,且系統(tǒng)性能不高、控制曲線會隨負載的變化而變化,轉(zhuǎn)矩響應慢、電機轉(zhuǎn)矩利用率不高,低速時因定子電阻和逆變器死區(qū)效應的存在而性能下降,穩(wěn)定性變差等。因此人們又研究出矢量控制變頻調(diào)速。
S7-1200通信和程序的特點:
S7-1200是西門子的新一代的控制器,在串口通信方面在硬件與軟件方面都與S7-200不同:通訊方面:作為200的升產(chǎn)品,1200不支持DP等應用比較廣泛的通訊協(xié)議,但保留了強大的自由口通訊功能;程序方面:引入塊概念,更接近于300,編程方便,尤其是通訊方面的編程(自由口、MODBUS等,一個塊可以控制多個驅(qū)動器,不同電機的數(shù)據(jù)存儲在不同的數(shù)據(jù)庫中;硬件方面:S7-1200現(xiàn)有的幾款PLC都可以擴展3個串口通信模板(即可以全部是RS232接口,也可以全部是RS485接口,也可以是兩種接口的組合),而S7-200這不可以進行擴展,只能用本體上的RS485口,在這一點上功能強了。軟件方面:S7-1200,在編程上與S7-300的編程方法類似,組態(tài)完硬件接口,直接調(diào)用功能塊就可以,非常簡單,不像S7-200需要對SM進行操作。S7-1200與S7-300在串口通信比較起來基本上一樣,但在作Modbus的通信時不需要額外的Dongle來支持。
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Lovejoy 3075-E Variable Speed Pulley 1-1/8in
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Loctite 983330R Rotospray Positive Displacement Pump
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Limitorque 60-503-0001-1 Declutch Arm
Limitorque 60-245-0115-3 Slinded Adapter 1-7/8in
Limitorque 2SYZ01153-A1-RU Torque Motor Fb56 3ph 0.67hp 1700rpm 460v-ac
Lightnin XJC-30 B77V3047N-DA 40gal Mix Tank Agitator 30hp 1425rpm 208-220/440vac
Lightnin V78R0222M-WN Permanent Magnet Mixer Motor Ef56c 1.17hp 1725rpm 180v-dc
Lightnin B77R3041N-NW Dura-mix Mixer Motor Wx180tz 3ph 2.3hp 1725rpm 220/440v-ac
Liberty Technologies STM-100 Peco Quickcal Stem 1-1/8in
Lh Research SM11-E0709/230 Power Supply Module
Lh Research SM11-E0676/115 Super-mite Power Supply Module
Lh Research MM44-E0675/115 Power Supply Module 445w
Lh Research MM43-E0952/115 Mighty-mite Power Supply 115v-ac 7/9a 5/12v-dc 370w
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Leybold TURBOTRONIK NT450 Turbo Pump Controller 120/240v-ac
Leybold- Heraeus TURBOVAC 150 High Vacuum Pump
Leybold D16B AR16-25 Trivac Rotary Vane Vacuum Pump 16m3/h 1hp 208-230/460v-ac
Leybold 960312 SV40 B Sogevac Vacuum Pump 1-1/2in 32.1cfm 2hp 230/460v-ac
Leybold 133101 SC15D Sc 15d Vacuum Scroll Pump 0.4kw 230v-ac
Leybold 130005 Ecodry M15 Vacuum Pump 15m3/h 0.9kw 100-240v-ac
Leslie 139260020 20ft Temperature Element 70-170f
Leser 4834.7714 Stainless Clean Service Safety Relief Valve 1-1/2x2in
Leroy Somer LS112M Ac Motor 3ph 2.2kw 855rpm 600v-ac