随着我国城乡建设的迅速发展,水、电供应不足的矛盾越来越成为人们关注的问题。例如,人们日常生活中的用水量越来越大,一天中的用水量的波动也越来越大。以往的供水系统中,水泵的选取往往是按最大供水量来确定,而实际的用水量在不断变化。高峰用水时间较短,这样水泵在很长一段时间内有较大余量,不仅水泵效率低,供水压力不稳,而且造成大量电力、水资源的浪费;并且以往依靠手动操作控制泵的启动、停止,也已不能满足要求。这里,介绍一种变频控制的恒压供水系统,它既能解决人工操作的繁杂劳动和精神压力,又能节约能源[5]。一、系统介绍该控制系统主要装置包括:可编程控制器(PLC)、变频器、压力传感器、PID控制器以及相关软件控制单元。该装置形成一套完整的、全自动的、智能的恒压供水控制系统,如图1所示。该系统能够以三种方式工作,分别为全自动、半自动和手动操作方式,其中后两种是在全自动方式出现故障时的弥补恒压供水系统全自动恒压供水控制原理当主水管网压力传感器的压力信号4~20mA送给数字PID控制器,控制器根据压力设定值与实际检测值进行PID运算,并给出信号直接控制变频器的转速以使管网的压力稳定。当用水量不是很大时,一台泵在变频器的控制下稳定运行;当用水量大到变频器全速运行也不能保证管网的压力稳定时,控制器的压力下限信号与变频器的高速信号同时被PLC检测到,PLC自动将原工作在变频状态下的泵,投入到工频运行,以保持压力的连续性,同时将一台备用的泵用变频器起动后投入运行,以加大管网的供水量,保证压力稳定。若两台泵运转仍,则依次将变频工作状态下的泵投入到工频运行,而将另一台备用泵投入变频运行。当用水量减少时,首先表现为变频器已工作在最低速信号有效,这时压力上限信号如仍出现,PLC首先将工频运行的泵停掉,以减少供水量。当上述两个信号仍存在时,PLC再停掉一台工频运行的电机,直到最后一台泵用主频器恒压供水[4]。另外,控制系统设两台泵为一组,每台泵的电机累计运行时间可显示,24小时轮换一次,既保证供水系统有备用泵,又保证系统的泵有相同的运行时间,确保了泵的可靠寿命。FanucA16B-2202-0401AllenBradley700-RTC31S300U1RikenKeikiGP-621DOmron,E5AX-LAF-XParker,P5G-AP6BCNRAS-AUnipulse,F362VEmerson,02-766390-01Yaskawa,SGMAH-A5A1A-YR21AS-B827-032JANCD-MM14DTZ1RE024BHA-C1903ThomsonIndustries,7828132NTAI06AL230A-7A2QS1E03AA-01ETR1FD3070LMML400-E25535,4B3NA2A-1436DC200C-0-00B-100000-0RB18025UUCC0-G1GP2HZ5-24VAC-2S-2O3RW3026-1BB04C11500836T-T352JX6SR33-017AMHW0171224-A,152339-1ENF602-3PB611SPG1209039FJ60aDC300K-A-2A3-21-0000-0FC-D980CAllenBradley,154-A11NBSiemens,6EP1-437-2BA00870BRDPCB4GF4MXQ16L-50C-M9BL5881-400,5881-0HF-KP13BXC50SGT-16-5N-NP-S680Unico,312-203.181-MT1746-NI41771-OAD-CAJ71UC24AU6627N2EAD,BTU5252006,5209822Rexroth,VT-5014,VT5014S31W200MLCFC,1A96682E01Rosemount,580D-101179B00713CR14V9363-B10-1K-20P1Dura,HSH7B,3-12JamesburyVPVL200-SR6-B-CBurkert,W33ML,00002428221367.55/150-5000803Banner,PVA225P6QMitsubishi,FR-A220E-0.75K-ULLabMasterDMA811962AllenBradley,194R-NU100-1753Valtorc,TJ26396Omron,CS1G-CPU42HSFR-13FR-20-50-20-51831-6SquareD,8502PG311V02AJ35TB1-16DTOpto22,G4RAXDC300E-0-000-20-0000-0Paragon500-132-0060-1664-3836T-T300JX9ESCV-2WPPC0038PX60-020-108Siemens3RK1300-1AS01-1AA1C-7704-1510ConeDriveMSHV20-X8BSpotWelderWelding,948-641IFMEfectorOD5007Fanuc,A02B-0236-C205AllenBradley,873C-DDNP1000E2Keyence,FT-50AHoneywell,R7248A100456T34D5328,9VB56T34D5328DBaldor,IDNM3534,35T995-1709G1HW9280784PHDR11A2180-A-DATV58HU09M2ZP56X1337Parker,D1VW008CNTCFHoneywell,SDS-C2BR-S8BentlyNevada,190501,160501-06-00-01Parker,D1VW008CNKCAllenBradley,836T-T300JHornerHESX1182300A1-09SMC,MGQM50-150-Y7BALAllenBradley1771-HS1IMC-121Fanuc,A16B-2200-0341ModiconAS-B824-016DX80G9M6S2P2M2M2ACTechLenzeSD230ModiconAS-B872-200SquareDVSD07U09P10MicroSwitch,21CX139749ESK-M001-D-517JANCD-MFC04-2RGBF05R12-502-MA16B-2200-07601771OWGV-H130MD20A-ZMBosch1070075324-102Siemens,505-6660PPTVision661-0114JD62T200108232ERCP-SA5-I-M-200-N-BE505-AOXD-105RDTICXT50,ER20KD3400Y700-PSDA1873C-DDNP1000E2,DDNP1000-E2Siemens,6SE3-190-0XX87-8BF0655-7686-001,OR20RTMAR50600ALET,0R20HGP-25-A-BHST26AAllenBradley,SP-120659,1336009-07204-01E0-61CB-1321Rees,04962-1006010P0,19990500835RM48-3R0GBKG-505W-8VLP-1000426T2-15PCA-6157-BARE,PCA-6157-P54420871-34340,PC871B,40-20-34341AC361RGRI34A063-0918G3315-925X1PC0.0075-0.5V/24/240VACDC7022AJSB11DSC63-A-41A-90A-R-S3-1.5PX60-020-108INBIM02HF-KP053DPNOZ8PTAI216EP260CV050D500DIM3224DDC230B-EE-2A-10-0000000-00-0SMC,SMC,EX250-SEN1Barksdale,425T2-17Danfoss,017A1692-01855TV-B10F3F7F6K1RedLion,IMD23107HD3-3W-BGA-03B-WYR3Pilz,PZE5V-0.5-3S-24VDC-4S-1OBentleyNevada,37506-A-05Mitsubishi,MR-J3-10BIFM,OO5002,005002Schmalz,SCP30FSVD,10.02.02.00911Fronius,4204100854,4045881CN77R344852S-NSBW8B11-00V-04Sick,149338,149338-38536SD01V08836T-T252JX403WE-10-B31CG24N9DALCC3-HB110E54-14407-2011785-L20B849-ZOD32855EC-B24Y7Y6Y5Y4Y3,719004-1S05B1P2PANS000VS0200/24vdcVS0200SR01007E89040-003,7723345-UB,ETH21RSC57901896TB,EBK50TCFIY0003F856.25hp1/4hp440v1725rpm801621190-2AutomotiveArmature,9312
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