1756-ENBT
¥1.00
F5109B
¥1.00
F6706
¥1.00
HIMA F7113
¥1.00
HIMA F7114
¥1.00
HIMA F7130A
¥1.00
AB 1747-DCM
1.4 冗余设计和降级操作设计
1) 对可靠性要求较高的应用场合，冗余设计和降级操作是必要的。冗余设计可采用热后备或冷后备方式。热后备方式操作时，冗余的后备系统也同时运行，两者输出的结果一致时，表示系统是正常运行的；一旦结果不一致，则发出警报信号，同时，根据自诊断的结果，切换到正常的系统去。冷后备方式操作时，冷后备系统不运行，它在自诊断检测出运行系统故障后才切入后备系统。对PLC来说，冗余系统的范围主要是CPU、存储单元、电源系统和通信系统，只有在可靠性要求很高时，才会包括输入输出单元的冗余等。
2) 降级操作是指在设计时，将手动操作包括在内的设计。例如，紧急停车的设计，关键设备的开停和再启动功能的设计等。这样，一旦发生故障，可采用降级的操作，即对部分或全部设备进行手动的开停操作，以避免设备的损坏或对人员的伤害。此外，在设计中也可考虑从全自动到半自动、直至手动的操作等。
1.5 PLC的I/O电路
1) 由于PLC是通过输入电路接受开关量、模拟量等输入信号，因此输入电路的元器件质量的好坏和连接方式直接影响着控制系统的可靠性。比如：按钮、行程开关等输入开关量的触点接触是否良好、接线是否牢固等。设备上的机械限位开关是比较容易产生故障的元件。在设计时，应尽量选用可靠性高的接近开关代替机械限位开关。此外，按钮的常开和常闭触点的选择也会影响到系统的可靠性。现以一个简单的起动、停止控制线路为例，如图2和图3所示的是两个控制线路和它们的对应梯形图。这两个控制线路的控制功能完全一样，按下起动按钮，输出动作；按下停止按钮，输出断开；但它们的可靠性不一样。我们假设输出断开为安全状态，那么图3的可靠性要比图2的高。这是因为SB1、SB2都有发生故障的可能，而最常见的现象是输入电路开路。当采用图3电路时，不论SB1、SB2开关本身开路还是接线开路，输出都为安全状态，***了系统的安全和可靠。
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SUN HYDRAULICS YDGE LHN CA/S SANDWICH BODY MANIFOLD HYD
NEW VICKERS DG18S-8-8C-10 3000PSI DIRECTIONAL CONTROL H
PARKER CPS600S PILOT OPERATED 5M-11 FLOW CHECK HYDRAULI
RACINE FF2 AHSJ 02L 01 STABALIZED FLOW CONTROL HYDRAULI
VICKERS SPC1-10-P-6T 3000PSI SINGLE PILOT 12GPM CHECK H
NEW CONTINENTAL HYDRAULICS VS12M-3L-GB-60L?-H DIRECTIONA
NEW PARKER DS161CRA120LC-1?2T 3/4IN NPT SOLENOID THREADE
VICKERS DGMFN-5P-Y-A2W-?B2W-30 SYSTEM STAK FLOW CONTROL
REXROTH 4WE10EA33/CG24N?9K4 MANNESMANN SOLENOID HYDRAULI
NEW HAWE RH2 PILOTED 3/8IN BSPP THREADED CHECK HYDRAULI
VICKERS FN-06-21 3/4IN NPT 20GPM THREADED FLOW CONTROL
REXROTH 4WE6Y62/EW110N9?K4/V/62 110/120V-AC SOLENOID HYD
NEW PARKER PCCM600S FLOW CONTROL 6GPM HYDRAULIC VALVE D
NEW TOKIMEC DG4V-3-2A-M-P7-?H-7-52 G1/2 24VDC DIRECTIONA
NEW REXROTH R900910785 R900966552 DIRECTIONAL SOLENOID
REXROTH 4WE6J60/EW110N9?K4 PROPORTIONAL 120V-AC SOLENOID
VICKERS PRM3PA25KN32 3000PSI DIRECTIONAL CONTROL HYDRAU
REXNORD FF1 SHP0 04H 01 FLOW CONTROL THREADED 1/2IN NPT
BARKSDALE 9043R0AC3-MC 1/2IN PRESSURE CONTROL 500PSI DI
VICKERS CM11N02-K25B1L-?21 DIRECTIONAL CONTROL HYDRAULIC
NEW VICKERS DG5S-8-2C-T-M-F?PBWL-B5-30 DIRECTIONAL CONTR
NEW PARKER PRDM2PP06SNN 1/4IN NPT PRESSURE REDUCING HYD
PARKER D1VW20BNYPF 75 120V-AC PILOT DIRECTIONAL CONTROL
SUN HYDRAULICS RPGC-JAV PISTON RELIEF CARTRIDGE HYDRAUL
VICKERS DG5S88CMWB20S32?4 120V DIRECTIONAL CONTROL SOLEN
DANA FE3-PAAD-M02S-2?4 1000PSI RELIEF 24GPM HYDRAULIC VA
PARKER D1VW20DNKWF75X 12VDC 5000/1500PSI SOLENOID HYDRA
NEW MANNESMANN 4WEH16C63/6EW11?0 N9ETDA REXROTH SOLENOID
NACHI SS-G03-A3Z-R-C1?15-E21 SOLENOID OPERATED DIRECTION
NEW REXROTH 4WE6D62/OFEW11N?09K4/62 5100PSI DIRECTIONAL
NEW VICKERS DG4S4-010A-50 CT 06 CB DG 0A 20 SOLENOID HY
SUN HYDRAULICS NB2 9JT5 ALUMINUM SANDWICH 20GPM MANIFOL
NEW DELTROL EDC30SS 1/2IN NPT CHECK THREADED HYDRAULIC
NEW WANDFLUH-HYDRAU?LIK AM4D101 DIRECTIONAL SOLENOID HYD
VICKERS DG4V-3S-6C208-M?-P12L-DJH5-60-E?N429 10.5GPM DIRE
VICKERS 4CT06A21 PILOT OPERATED CHECK HYDRAULIC VALVE B
NEW DYNEX 6550-02-115/DF-?T-71 115V-AC 3000PSI SOLENOID
NEW PARKER CP600S5M 3/8IN NPT PILOT OPERATED CHECK HYDR
VICKERS DGMFN 5 Y AW BW 20 FLOW CONTROL HYDRAULIC VALVE
SWAGELOK SS-V3NBF8-FL STAINLESS 1/2 IN THREADED MANIFOL
NEW PARKER D3W20HNYW 5000PSI SOLENOID HYDRAULIC VALVE 1
PARKER D3W4CNYP 14 120V-AC 0-20GPM DIRECTIONAL CONTROL
VICKERS DG5S-5-2C-T-M-U?-H7-21 DIRECTIONAL CONTROL HYDRA
VICKERS DG5S 8 8C T S MPB WLB 20 0-20GPM DIRECTIONAL HY
SUN HYDRAULICS GBY 9IW6 SANDWICH NCCB LCN BODY MANIFOLD
NEW HYDAC SAF20M12T210A HYDRAULIC ACCUMULATOR SAFETY SH
TEITTINEN K-DFV 12-360 COUNTERBALANCE CONTROL HYDRAULIC
NEW VICKERS PCGV 8F 1 10 PILOT OPERATED 350 BAR CHECK H
REXROTH 2FRE 6A-21/25QRV HYDRONORMA GP45B4-A PROPORTION
VICKERS DG4S4W 018C B 60 DIRECTIONAL CONTROL SOLENOID H
MOOG D635-101E R08FB1F0NSS2M DIRECT DRIVE 24V-DC SERVO
NEW PARKER PRC3PF PRESSURE CONTROL HYDRAULIC VALVE D253
NEW INTEGRATED 1GR100P2S RELIEF VALVE HYDRAULIC IHJ20 C
NEW VICKERS CT5060ACMFWB510?0 RELIEF SOLENOID HYDRAULIC
NEW COMMAND CONTROLS EMDV-12-N-C2-0-?00 11***G HYDRAULIC
NEW VICKERS C2815S8 3/4IN NPT CHECK THREADED HYDRAULIC
NEW VICKERS C2815S8 3/4IN NPT CHECK THREADED HYDRAULIC
NEW PARKER D1VW004CNYWH 120V-AC 5000PSI SOLENOID HYDRAU
NEW TOKIMEC DG4V-3-2A-M-P7-?H-7-54 24V-DC SOLENOID HYDRA
NEW VICKERS DG4V-3S-6C-VM-F?W-B5-60 5000PSI SOLENOID HYD
VICKERS DG4S4-016C-U-H-?60 SOLENOID OPERATED DIRECTIONAL
DANA FE3-PAAD-M02S-2?4 1000PSI 24GPM RELIEF HYDRAULIC VA
NEW PARKER D1VW001ENYGF56 DIRECTIONAL 120V-AC SOLENOID
MOOG D663E775B D061-724C SERVO HYDRAULIC VALVE D445378
NEW CLARK 2330662 SAUER DANFOSS 1/2IN NPT FLOW CONTROL
VICKERS 879279 DG4S4-012A-U-B-?60 DIRECTIONAL SOLENOID V
PARKER D1BW20HY21 115V DIRECTIONAL CONTROL VALVE B20193
NEW VICKERS RCG-10-B3-30 PRESSURE CONTROL HYDRAULIC VAL
NEW REXROTH DBDS 6 P1A/100 THREADED RELIEF HYDRAULIC VA
VICKERS DG5S-8-31C-E-T-?MUH-9-B10-20 DIRECTIONAL CONTROL
REXROTH 4WE6J51/AW-120-?60NZ45V 120V DIRECTIONAL CONTROL
NACHI SS-G03-A3Z-R-C1?15-E21 SOLENOID OPERATED DIRECTION
NEW FLUID CONTROLS 1G10-P-20SV FLOW CONTROL HYDRAULIC V
HUSCO 5000-B-200 G THREADED DIRECTIONAL CONTROL HYDRAUL
VICKERS 02-119626 DG4S4 012A B 60 S324 DIRECTIONAL HYDR
SUN HYDRAULICS DBY 9ED6 THREADED MANIFOLD HYDRAULIC VAL
NEW PARKER VMY160L06NV1P 160 BAR SOLENOID HYDRAULIC VAL
VICKERS DG4V-3S-2C-M-FW?L-B5-60-EN21 10.5GPM DIRECTIONAL
SUN HYDRAULICS DBY 9IN5 ALUMINUM SANDWICH 12GPM MANIFOL
DOWTY-YUKEN DSHG-06-3C60-A1?20-3590 DIRECTIONAL SOLENOID
NEW VICKERS CS-06-CB-DG-0A-?M-U-B5-40 RELIEF SOLENOID HY
NEW REXROTH M-3SEW6C36/630M?G96N9K4 SOLENOID HYDRAULIC V
NEW MOOG D651-403D P70XBEAAN6A0K 200 BAR 15V-DC SERVO H
MOOG D651-403A P70FBX3ANFN SERVO HYDRAULIC VALVE B40018
VICKERS C2-529C ROTARY LEVER PILOT DIRECTIONAL CONTROL
NEW REXROTH 4WE6E62/EW110N9?DA/62 120V AC HYDRAULIC SOLE
REXROTH 4WRZ32W3-520-31?/S0204R PROPORTIONAL DIRECTIONAL
BOSCH 4WRLE10W-80SJ-3?X/G24ETK0/A1WX0?2M747 SERVO SOLENOI
MOOG 760-87*** SERVOVALVE 760 SERIES ELECTRO SERVO HYDRA
NEW DAYTON 1A320B CLOSED CENTER SPOOL 10GPM SOLENOID HY
SUN EB3 COUNTER BALANCE BODY PBDB LQN CARTRIDGE MANIFOL
NEW VICKERS DG5S-8-2A-E-M-F?W-B5-30 120V-AC SOLENOID HYD
NEW VICKERS DG5S-8-2C-2-M-F?W-B5-30 HYDRAULIC DIRECTIONA
NEW PARKER D3W4CVYPH 120V DIRECTIONAL CONTROL SOLENOID
ENERTECH 6C2T3012 105-140V-DC 3000PSI HYDRAULIC VALVE B
NEW REXROTH M-4SEW6D36/630 MG96N9K4 SOLENOID HYDRAULIC
NEW REXROTH R900217121 96V-DC 30W SOLENOID HYDRAULIC PO
REXROTH DZ 30-1-52/200XM/1?2 DIRECTIONAL CONTROL HYDRAUL
NEW VICKERS XG 06 2F 30 REDUCING PRESSURE CONTROL HYDRA
VICKERS DF5S4L 162A E 53 DIRECTIONAL CONTROL HYDRAULIC
MOOG 631-266C FLOW CONTROL PROPORTIONAL SERVO HYDRAULIC
NEW BOSCH 9 810 161 089 FF1 SH MH 01 H 50 4500PSI HYDRA
NEW JERGUSON 136 3/4IN X 1/2IN TUBULAR 2400PSI GAGE VAL
HYSTER 0290921 PARKER HF30888-3 DIVIDER FLOW MANIFOLD H
NEW SIEMENS SKP10.192U17 ELECTRO-HYDRAUL?IC ACTUATOR 120
TOYOOKI KOGYO SOLENOID DIRECTIONAL CONTROL HYDRAULIC VA
VICKERS QJ 5M 0 242A3 HS DC24 DOUBLE A SOLENOID HYDRAUL
NACHI S-G01-C6-GRZ-D1?9-9390D 31.0 SOLENOID HYDRAULIC VA
PARKER D1VW20DNJWF 75 SOLENOID HYDRAULIC VALVE D290251
PARKER D1VW20HY40 1/2IN NPT SOLENOID THREADED HYDRAULIC
VICKERS PBDG4S4L016CB60 INSTA-PLUG DIRECTIONAL PILOT HY
VICKERS PA5-DG4S4LW-02A?-B-60LH DIRECTIONAL PILOT SOLENO
CONTINENTAL VS5M-1A-GMBT-68?L-K 1500PSI 120V-AC SOLENOID
VICKERS 880024 PBDG4S4L 016C B 60 INSTA-PLUG DIRECTIONA
YUKEN DSHG-06-3C60-AT?20-3590 KOGYO DIRECTIONAL CONTROL
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