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正确选择接地点，完善接地系统
良好的接地是保证PLC可靠工作的重要条件，可以避免偶然发生的电压冲击危害。接地的目的通常有两个，其一为了安全，其二是为了抑制干扰。完善的接地系统是PLC控制系统抗电磁干扰的重要措施。
PLC控制系统的地线包括系统地、屏蔽地、交流地和保护地等。接地系统混乱对PLC系统的干扰主要是各个接地点电位分布不均，不同接地点间存在地电位差，引起地环路电流，影响系统正常工作。例如电缆屏蔽层必须一点接地，如果电缆屏蔽层两端A、B都接地，就存在地电位差，有电流流过屏蔽层，当发生异常状态如雷击时，地线电流将更大。
此外，屏蔽层、接地线和大地有可能构成闭合环路，在变化磁场的作用下，屏蔽层内又会出现感应电流，通过屏蔽层与芯线之间的耦合，干扰信号回路。若系统地与其它接地处理混乱，所产生的地环流就可能在地线上产生不等电位分布，影响PLC内逻辑电路和模拟电路的正常工作。PLC工作的逻辑电压干扰容限较低，逻辑地电位的分布干扰容易影响PLC的逻辑运算和数据存贮，造成数据混乱、程序跑飞或死机。模拟地电位的分布将导致测量精度下降，引起对信号测控的严重失真和误动作。
WEIR 24718 GALIGHER 5-VANE 21IN OD 2-1/4IN BORE PUMP IMPELLER D568095
VALVCON SVW600FTE2S115VAC ELECTRIC VALVE 115V-AC ACTUATOR D574426
ROTEX ECV350E-80 125PSI PNEUMATIC VALVE ACTUATOR D568331
EL-O-MATIC F0350U PNEUMATIC VALVE ACTUATOR 120PSI D596961
ALFA LAVAL UNIQUE 7000 PN10 TRI-CLOVER SANITARY STAINLESS VALVE ACTUATOR D599552
UNITORQ UTQ-020 QUARTER-TURN ELECTRIC VALVE ACTUATOR 120V-AC D599857
KINETROL 090 SPRING TO CENTRE PART-TURN ROTARY ACTUATOR D600109
WARREN RUPP 870.202103 DA101PPTAS00 PUMP SURGE DAMPENER PP/PTFE D585285
STAINLESS SUCTION PLATE SIDE FOR 18X18X23IN PWO PUMP D518515
8-VANE 15-1/8 IN OD BRASS PUMP IMPELLER D513000
AUMA SA 10.1 AD0071-4/80 1HP 460V-AC 54RPM VALVE ACTUATOR D539133
BAILEY 258299A2521B 1 TRANSDUCER SPARE PARTS KIT D526109
MARTIN C348 1-9/16IN STOCK BORE SPUR GEAR D547757
FLOWSERVE GEB1350835A 4-3/4IN STAINLESS PUMP GLAND RING ASSEMBLY D518920
M-18VEM3AX15 6-VANE 18 IN OD 2-7/8 IN ID STEEL PUMP IMPELLER D538124
WATTS RK 909-CK1 4 0887212 FIRST CHECK VALVE REPAIR KIT D579444
JOHN CRANE 2-3/8 IN TYPE 315RS MECHANICAL PUMP SEAL KIT D580059
MASONEILAN DRESSER 7401-700 7400 VALVE POSITIONER D583390
SULZER K205 REPAIR KIT D577021
WARREN RUPP DA101PPTAS00 PUMP SURGE DAMPENER PP/PTFE D585170
WARNER ELECTRIC 5202-111-001 ARMATURE W/ ADAPTER EP/SF-1000 D585722
3-VANE 16IN OD 2-9/16 IN BORE STAINLESS PUMP IMPELLER PUMP D581990
BUFFALO PUMPS G 2722 STEEL CENTRIFUGAL PUMP CASING 3X4IN D582023
WARREN RUPP DA101PPTAS00 PUMP SURGE DAMPENER PP/PTFE D599907
CRANE 146355007 PRESSURE SEAL RING 8-5/16X9-3/4X15/16IN STEEL D531896
EL-O-MATIC ED0150.U1A00A.22K0 PNEUMATIC VALVE ACTUATOR D596955
WATTS RK 909 VT 4-6 RELIEF VALVE REPAIR KIT D583218
6-VANE 18IN OD 3-3/4 IN ID BRASS PUMP IMPELLER D538603
7-VANE 14 IN OD BRASS PUMP IMPELLER D527162
FLOWSERVE 122699 3IN COLLAR STAINLESS PUMP SHAFT SLEEVE D511868
LABOUR SIZE 45 TYPE SQ PUMP POWER END D522759
8-VANE 16IN OD 2-11/16IN ID BRASS PUMP IMPELLER D532345
NU-CON DT 1250DEM ROTARY VALVE EASY SLIDE SUPPORT D548918
8-VANE 16IN OD BRASS PUMP IMPELLER D532382
7-VANE 14IN OD 2-3/8IN ID BRASS PUMP IMPELLER D533443
SPENCER TURBINE 401001 CCI ALUMINUM BLOWER FAN WHEEL 23IN 12-VANE D595119
FLOWSERVE KA95213 2R41732DB-CO599729 STAINLESS PUMP SEAL D595475
ROSEMOUNT 03031-1C SPARE MODULE ASSEMBLY D595617
DRESSER 710001189-AAWA PRESSURE BOUNDARY SEAL ASSEMBLY BELLOW D595406
EL-O-MATIC ES0150.U2A04A.22K0 PNEUMATIC VALVE ACTUATOR D596939
EL-O-MATIC ED0150.U1A00A.22K0 PNEUMATIC VALVE ACTUATOR D596937
GOULDS 55461 IRON PUMP IMPELLER 6-VANE 11-1/8IN OD D597532
FOXBORO C0134BX PNEUMATIC CONTROLLER CONTROL UNIT D599220
CHESTERTON S10/OS CASSETTE TYPE CARTRIDGE OVERSIZE SEAL 1.750IN D599633
MOORE PSD-4-20MA/PRG/2.3VLP/-LMD PROGRAMMABLE TRANSMITTER LOOP DISPLAY D599382
METSO MA RL SS SS RDU VALMETSP CONSISTENCY TRANSMITTER DISPLAY UNIT D599791
SIHI PUMPS 65009477 PUMP SHAFT D567372
MASONEILAN DRESSER 7401-700 7400 VALVE POSITIONER D569011
NELES CONTROLS NE724/S1 ELECTRO-PNEUMATIC POSITIONER D569236
LABOUR SIZE 35 TYPE SQ PUMP POWER END D522760
INTERTEC KA87-KIT DIABOX 87SE INSTRUMENTATION ENCLOSURE D529010
BAILEY AV122100 150PSI PNEUMATIC VALVE POSITIONER D583281
DEZURIK 870022-011-11-13-01-27-00 ELECTRO-PNEUMATIC POSITIONER D590141
GOULDS 104-995-1-120 6VANE 11IN STAINLESS IMPELLER 1-9/16IN BORE D590982
BETTIS CBB315-SR40 PNEUMATIC DOUBLE ACTING VALVE ACTUATOR 155PSIG D591396
NORTON 57A36-O5VBE GRIT COARSE GRINDING WHEEL 18X3X1-1/2IN 1805RPM D592119
KOP-FLEX 2360477 2360550 COUPLING DISC PACK AND HARDWARE KIT D591430
ASCO 671774 RED-HAT 208-240V SOLENOID VALVE COIL D588606
SMC CLA2-100-E-UT-X1209 CLA/CLA2 TIE-ROD CYLINDER LOCK UNIT D593801
ASCO 102846 REBUILD KIT SOLENOID VALVE REPLACEMENT PART D590716
FISHER DVC6025 FIELDVUE VALVE POSITIONER D523661
CHESTERTON 442HP/R 145M SA CR/CB S EP 645207R STAINLESS SEAL KIT D518098
WALWORTH CB03532 600PSI STEEL SMART 6IN GATE VALVE STEM D514983
WILDEN 15-9660-99 P15 METAL AIR SECTION REPAIR ADS KIT D522074
LABOUR SIZE 30 TYPE SZ PUMP POWER END D522761
JOHN CRANE K13614RBA TYPE 604 STAINLESS PUMP SEAL 4 IN D529035
CHESTERTON 687485 442 SEAL SIZE 58 SHAFT 7.25IN STAINLESS PUMP SEAL D537408
REXNORD 020361 THOMAS DPK DBZ 351 HHS COUPLING DISC KIT STAINLESS D518812
JOHN CRANE T8-1T EDM-1060 XF1O101 1.375 MECHANICAL PUMP SEAL KIT D580051
JOHN CRANE 676LGC-SGF727-46 MECHANICAL PUMP SEAL D580057
CHESTERTON S10 198845 CASSETTE TYPE CARTRIDGE PUMP SEAL 70MM D580354
FLOWSERVE A2R67247-01 QBB/QBW33755U9X/5UDB/DB PUMP SEAL ASSEMBLY D580250
NORTHERN PUMP 4347-01-C1732 PUMP FLANGE ASSEMBLY D584155
BUFFALO PUMPS PC6384C-05 CENTRIFUGAL STEEL PUMP CASING 1-1/2X3IN D581643
11-3/4 IN OD 7 VANE BRASS PUMP IMPELLER PUMP D591849
BETTIS CBB315-SR40 PNEUMATIC DOUBLE ACTING VALVE ACTUATOR 155PSIG D591397
WARMAN E4041-19MA05C STEEL PUMP FRAME PLATE LINER INSERT D599391
FISHER 25A5711X012 CONTROL VALVE SEAT RING 1/4 IN D545676
UNITORQ M148K44DLS M-SERIES PNEUMATIC ACTUATOR D599873
ARMSTRONG 310 STEEL FLANGED 3/4IN STEAM TRAP 200PSI D590987
PLAST-O-MATIC EBV-104 TRUE BLUE 120V-AC 2A 1PH ELECTRIC VALVE ACTUATOR D587033
SULZER 2839110141 230 STEEL PUMP IMPELLER 10-1/2IN OD 6-VANE D589226
REXROTH 0 608 701 018 NUTRUNNER MOTOR 0-230V-AC 0.28A 0.12NM D593792
6-VANE 18IN OD 2-7/8 IN ID STEEL PUMP IMPELLER D538605
CHESTERTON 442HP 145M SA CR/CB S EP 645207 PUMP SEAL 5.708IN SHAFT D518097
FLOWSERVE 304003ER 4X6 IN FLANGED 13-1/2IN ID PROCESS PUMP CASING D540594
LABOUR SIZE 20 TYPE SZ PUMP POWER END D522395
TIMKEN LM742714 TAPERED ROLLER BEARING CUP D522719
INGERSOLL RAND IRON PUMP POWER END D517545
JOHN CRANE K13614RBA TYPE 604 STAINLESS PUMP SEAL 4 IN D538314
WATTS RK909-CK14 0887212 FIRST CHECK REPAIR KIT D571099
MASONEILAN DRESSER FVP110 F1A3N/LC1/FF1 VALVE POSITIONER 20-60PSI D569605
REXROTH 0 608 701 018 NUTRUNNER MOTOR 0-230V-AC 0.28A 0.12NM D594316
GREER 704337 HYDRAULIC ACCUMULATOR BLADDER REPAIR KIT D564446
FLOWSERVE B175SFCW DA AUTOMAX ACTUATOR D561931
581AGJ70 STAINLESS PUMP SHAFT 1-7/8 X 30-7/16IN D595044
RADIUS AD-060 DOUBLE ACTING PNEUMATIC VALVE ACTUATOR 120PSI D595141
SAMSON 2413 STEEL DIAPHRAGM ACTUATOR 35-90PSI D595568
SMI NA SILENCER PNEUMATIC FILTER 1-1/2IN NPT W/ 4IN FILTER D596391
WARREN RUPP TA1 B-1-SS TRANQUALIZER PUMP SURGE SUPPRESSOR 1IN NPT D596105
RIKEN SEIKI 501028 COLLET CHUCK D596358
EL-O-MATIC F0200U PNEUMATIC VALVE ACTUATOR D596946
SIEMENS 760E11AAAGNND6 SERIES 760 VALVE POSITIONER D597324
FLOWSERVE 2R77926DB STAINLESS PUMP SEAL D598920
CHESTERTON S10 182063 CASETTE TYPE CARTRIDGE SEAL STAINLESS 1.750 D599711
SVF H25 SR2CZ COMPACT PNEUMATIC VALVE ACTUATOR D599836
BECK 20-2704-21 VALVE ACTUATOR MOTOR ASSEMBLY 1.5NM D584154
BECK 20-2704-21 VALVE ACTUATOR MOTOR ASSEMBLY 1.5NM D583797
CKD FJ-0-36 FLOATING JOINT UNIT PNEUMATIC FITTING D596393
FLOWSERVE 979389-001-Q1 MECHANICAL STAINLESS PUMP SEAL D523575
VICKERS 50FC 1F 12 737220 HOUSING UNIT D518023
7-VANE 9-1/4 IN OD BRASS PUMP IMPELLER D527166
6 VANE 3-1/2IN ID 16-1/2IN OD STAINLESS PUMP IMPELLER D524516
JOHN CRANE 1-RBA51208 TYPE 48MP STAINLESS PUMP SEAL D52887
