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隨著PLC在工業(yè)控制中的推廣普及,PLC產(chǎn)品的種類越來越多,其結(jié)構(gòu)型號(hào)、性能、容量、指令系統(tǒng)、編程方法等各不相同,適用場(chǎng)合也各有側(cè)重。因此,合理選擇 PLC,對(duì)于提高PLC在控制系統(tǒng)中的應(yīng)用有著重要作用。
可編程序控制器(以下簡(jiǎn)稱PLC)是在程序控制器和微機(jī)控制器的基礎(chǔ)上發(fā)展起來的微機(jī)技術(shù)和繼電器常規(guī)控制概念相結(jié)合的產(chǎn)物。從廣義上講,PLC是一種計(jì)算機(jī)系統(tǒng),比一般計(jì)算機(jī)具有更強(qiáng)的與工業(yè)過程相連接的輸入輸出接口,并已成為自動(dòng)化控制系統(tǒng)的基本裝置。PLC已經(jīng)廣泛應(yīng)用于機(jī)械、冶金、化工、汽車、輕工等行業(yè)中,已基本取代了傳統(tǒng)的繼電器和接觸器的邏輯控制。用PLC來控制系統(tǒng)設(shè)備,其工作的可靠性要比單純繼電器和接觸器控制大大提高。就PLC本身而言,平均無故障時(shí)間一般已可達(dá)3~5萬小時(shí);而三菱的F系列,據(jù)稱其平均無故障時(shí)間已達(dá)30萬小時(shí)。所以,整個(gè)PLC控制系統(tǒng)的可靠性,主要取決于PLC的外圍設(shè)備,比如輸入器件中的行程開關(guān)、按鈕、接近開關(guān),輸出器件中的接觸器、繼電器和電磁閥等。另外,從軟件程序的編制來考慮,如果能編制出一個(gè)帶有監(jiān)控的程序,對(duì)提高系統(tǒng)的可靠性也有很大好處。下面就如何提高PLC控制系統(tǒng)的可靠性進(jìn)行一些探討。
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LADISH 2" 275PSI@100°F CHECK VALVE 8273-0714-20B
HonEYWELL SKINNER VALVE 120 VOLTAGE A 3 LB 2 127AB96A46 NIB
POWELL VALVE 3/4" 1975PSI@100°F GLOBE VALVE GL08SA58GB
FLOWSERVE ULTRASWITCH W/ COMPACT ACTUATOR C25 SR-2C IMP & 1IN 150 CF8M VALVE
CAT PUMP VALVE KIT 33835
AUTOMATIC VALVE 10BAR 150PSIG PNEUMATIC SOLENOID VALVE 413B65S31C-DB7
SMC 3 VALVE MANIFOLD base PLASTIC THREAD AT END CRAKCED
MAXON 3/4" 125 PSIG SHUT-OFF VALVE, 5000-0
SMC 0-0.5MPA 1" NPT SOLENOID PROCESS VAVLE V0307-5TZ
FAIRBANKS 8" GATE VALVE 104043
NUMATICS 24VDC 6W SOLENOID VALVE 030SA446E000061?/236-115B
NORGREN 30-150PSI 1/4"NPT SOLENOID VALVE 375-02-007-32-0?2/00 *NNB*
PARKER * ConTROL SOLENOID VALVE * D3W1B56Y
GRACO VALVE SERVICE KIT 560-001-960 *NEW*
SMC 0-0.5MPA 1" NPT SOLENOID PROCESS VAVLE V0307-5TZ
FAIRBANKS 8" GATE VALVE 104043
NUMATICS 24VDC 6W SOLENOID VALVE 030SA446E000061?/236-115B
PARKER * ConTROL SOLENOID VALVE * D3W1B56Y
GRACO VALVE SERVICE KIT 560-001-960 *NEW*
ARMSTRONG THERMOSTATIC STEAM TRAP D1175-5 NIB
SMC SOLENOID VALVE VP3145-045DZB1-?NSW/2 225-344B
FABRI-VALVE 150CWP S316 10" KNIFE GATE VALVE F440745 67
NUMATICS 1/4"NPT REGULATOR VALVE NO GAUGE I34RD100J0503K0?0
SHICK 8" I.D. 11" O.D. STAINLESS STEEL ROTARY VALVE T-224
PARKER DIRECTIonAL VALVE D1VW001CVYCF4
ROSS ConTROLS 150 PSIG 1-1/4" NPT PILOT OPERATED CHECK VALVE, 2751B7901 NNB
SMC 26V .15-1.0MPA SOLENOID VALVE NVFS2400 *NEW*
BOSCH 1700PSI PRESSURE REDUCING VALVE 0 811 145 115 *NEW*
WATTS REGULATOR 600 PSI 3/4" NPT BRASS BALL VALVE, B-6800
VICKERS ALUM VALVE HOUSING 23035 REV. 3
APOLLO 1/2" LOCKING BALL SHUT OFF VALVE 70-103-27
TOYO-OKI WHD3A-D-V30-BCA?-025A-S1D VALVE W/ TOYOOKI ECAD-MS-S1D
ACCUTRAK 1040 DUAL DISPLAY W/ 3" OPEN/CLOSE 2KE VALVE 104357
metaLWORK PNEUMATIC REGULATOR VALVE
NUMATICS 150PSI DOUBLE SOLENOID VALVE 152JJ441O000000 *NEW*
WILKERSON 3/8" PORT / 3/4" THREADS SOLENOID VALVE N28-06-0C00
METREX VALVE WATER REGULATING VALVE 50-250PSI
PARKER 120/110V, 60/50HZ, .72-.75A, 3000 PSI, DIRECTIonAL ConTROL VALVE D3W1HNYC
SMC/ FLC 3/8"NPT FLOW SWITCH W SOLENOID VALVE AND PLUG ATTACHMENT L-61456/VX2330
WANDFLUH SOLENOID VALVE P135V-M40 NIB
NUMATICS 150PSI SOLENOID VAVLE 554JK43AO *NEW*
FLOWSERVE DURA SEAL PUMP SEAL CARTRIDGE GKB2135501B NIB
MODULAR DIVIDER VALVE SUB-PLATE NPSF
NUMATICS SOLENOID VALVE 11DSA-4410
SMC PNEUMATIC VALVE VHS4500-03
NUMATICS 150PSIG PNEUMATIC SOLENOID VALVE 031SA446C000030 / 237-958B NIB
NUMATICS 150PSIG PNEUMATIC SOLENOID VALVE ISO5599/11 / 134BB400KP
ARMSTRON MACHINE WORKS AM-91 STEAM HUMIDIFIER, NNB
DELTROL ConTROLS 24VDC 6.5W 90PSI SOLENOID VALVE DSV28-090-A08F-?P91 99344
SERVICE FIRST THERMO EXPANSION VALVE VAL04911 NIB
NORGREN 0-60PSI 0-4.0BAR PRESSURE GAUGE
PARKER 24VDC 3.0A 5000 PSI HYDRAULIC SOLENOID VALVE, D1FXE01FCVDJ004?0 NNB
ROSS PORT RIGHT ANGLE PO CHECK VALVE 1958A1010 NNB
HUNT VALVE COMPANY 150PSI, 250PSI FLO-DIRECTOR VALVE MODEL 43
ASCO MP-C-080 / 238210-032D SOLENOID VALVE COIL
MAC 15W 120/40V PNEUMATIC SOLENOID VALVE 250B-181CAAA
MAC VALVE REPAIR KIT K-09001C
REXROTH PNEUMATIC VALVE NIB 0820 402 046
LUBRIQUIP SHUT-OFF VALVE 527-005-180
ASCO SOLENOID VALVE 8551A001MS 99686
NUMATICS 150PSIG PNEUMATIC SOLENOID VALVE 031SA400C / 237-958B NIB
ROSS 20.7BAR MAX LINE FILTER REGULATOR 5211B5027 100070
UNKNOWN MFG * EASY READ VALVE * EF 35 B
JAMESBURY 18" BUTTERFLY VALVE ACTUATOR ST-1800 MOD. A
ASCO SOLENOID VALVE 120/60 MP-C-080 272610-132-D
SUN HYDRAULICS 1000PSI RPEC FAN RELIEF VALVE 89341 71110 NIB
SUN HYDRAULICS VAVLES 60069-C NIB
JAMESBURY ST-400B ACTUATOR 8" 316SS BUTTERFLY VALVE 815W-11-3600-MT W/ P-2000
NUMATICS 120V .11A 150 PSIG-AIR PNEUMATIC SOLENOID VALVE, 152SA400K
NUMATICS 150PSIG SOLENOID VALVE 237-1008B / 237-1011B / 031SS6002000030
NUMATICS 120V .16A 50/60HZ 150 PSIG-AIR SOLENOID VALVE, 33DSP4410 *REPAIRED*
NUMATICS 110/120V .37A 150 PSIG-AIR SOLENOID VALVE W/ base, I35SA43BK066E30
BOSCH 4500PSI 315BAR PRESSURE REDUCING VALVE 0 811 150 234
ASCO 110/120V 25PSI SOLENOID VALVE 821BB 0