描述
當(dāng)中性點(diǎn)直接接地系統(tǒng)(又稱(chēng)大接地電流系統(tǒng))中發(fā)生接地短路時(shí),將出現(xiàn)很大的零序電壓和電流。還有在中性點(diǎn)不直接接地系統(tǒng)中當(dāng)發(fā)生單相接地時(shí),也會(huì)產(chǎn)生零序電壓。零序電源在故障點(diǎn),故障點(diǎn)的零序電壓最高,系統(tǒng)中距離故障點(diǎn)越遠(yuǎn)處的零序電壓就越低,取決于測(cè)量點(diǎn)到大地間阻抗的大小。
正序、負(fù)序、零序的出現(xiàn)是為了分析在系統(tǒng)電壓、電流出現(xiàn)不對(duì)稱(chēng)現(xiàn)象時(shí),把三相的不對(duì)稱(chēng)分量分解成對(duì)稱(chēng)分量(正、負(fù)序)及同向的零序分量。只要是三相系統(tǒng),就能分解出上述三個(gè)分量(有點(diǎn)象力的合成與分解,但很多情況下某個(gè)分量的數(shù)值為零)。對(duì)于理想的電力系統(tǒng),由于三相對(duì)稱(chēng),因此負(fù)序和零序分量的數(shù)值都為零(這就是我們常說(shuō)正常狀態(tài)下只有正序分量的原因)。當(dāng)系統(tǒng)出現(xiàn)故障時(shí),三相變得不對(duì)稱(chēng)了,這時(shí)就能分解出有幅值的負(fù)序和零序分量度了(有時(shí)只有其中的一種),因此通過(guò)檢測(cè)這兩個(gè)不應(yīng)正常出現(xiàn)的分量,就可以知到系統(tǒng)出了毛?。ㄌ貏e是單相接地時(shí)的零序分量)。
零序電壓是三相線路中一相或者兩相接地產(chǎn)生的,大小取決于接地的程度,是金屬接地,非金屬接地,就是接地電阻了。
歐美品牌停產(chǎn)的,常用的“PLC”備品備件
我司產(chǎn)品應(yīng)用于以下領(lǐng)域:
1,《發(fā)電廠DCS監(jiān)控系統(tǒng)》
2,《智能平鋼化爐系統(tǒng)制造》
3,《PLC可編程輸送控制系統(tǒng)》
4,《DCS集散控制系統(tǒng)》
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5,《智能型消防供水控制系統(tǒng)》
6,《化工廠藥液恒流量計(jì)算機(jī)控制系統(tǒng)》
7,《電氣控制系統(tǒng)》造紙,印染生產(chǎn)線,變電站綜合自動(dòng)化控制系列
本特利,英維思,伍德沃德,??怂共_、西屋、瑞恩、施耐德莫迪康、ABB、AB、西門(mén)子、摩托羅拉、GE發(fā)那科、安川、博世力士樂(lè),ACSO,力士樂(lè)等各大品牌的DCS系統(tǒng)配件,機(jī)器人系統(tǒng)配件,大型伺服系統(tǒng)備件。
CONVUM VACUUM GENERATOR,TYPE CV-20LSCK
Convum MPS-V2R-G Vacuum Sensor
PARKER/CONVUM VACUUM AIR GENERATOR CV-30AHSN
Lot/4 Convum PS-50-F Vacuum Suction Pads
1 NIB CONVUM MPS-V3RC-GHA VACUUM SENSOR MPSV3RCGHA
PARKER CONVUM VACUUM SOLENOID VALVE MC2S10HSZM24B5N
Convum Vacuum Solenoid CVA-15HS
CKD CONVUM 3/8″PORT VACUUM FILTERS VF-6
CKD CONVUM 1/4″PORT VACUUM FILTERS VF-5
Convum PF-50 Vacuum Suction Pad
CONVUM VF-5 VACCUM GENERATOR FILTER CV-15,MCA-10/13
CONVUM FILTER VF-5 MYOTOHU COMPRESSOR FILTER 1/4 NPT
Parker Convum TYS-20B-30 Bulkhead Level Compensator
Myotohu Convum CVA-15QS Vacuum Actuator
CONVUM CVK-15HRZD PRESSURE SOLENOID VALVE CONVUM
Parker Convum CV-25HSN
CONVUM CVA-15HS35GDN NSFP CVA15HS35GDN
CONVUM MYOTOHU CVT05HS
PARKER CONVUM VACUUM SOLENOID VALVE MC2S07HSZM24B5N
CONVUM CV-15HS NSFP CV15HS
Convum Pneumatic Valve Manifold CVK-15HRZD Lot of 2
CONVUM CVA-15OS USPP CVA15OS
CONVUM CVA-15QS USPP CVA15QS
DNS CONVUM SENSOR,DIGITAL 2-AE-J0043 D4M5-GHA-D4
CONVUM CV-10HSCK NSFP CV10HSCK
CONVUM VF-3 VACUUM FILTER 1/8″
Convum APS030-PNP-SA2 Vacuum Sensor
CONVUM VACUUM FILTERS VF-6
CONVUM CV-10LS USPP CV10LS
Convum Manifold Solenoid Valve CVK-15HRZD 24V MVS SMC
CONVUM CVA-10LSB NSPP CVA10LSB
PARKER CONVUM PF-120D VACUUM CUP PAD
PARKER CV15HSN CONVUM VALVE CV-15HSN 1/4 INCH 1/4″
Convum Myotoku CVK-15HRZD 24BD Pneumatic Solenoid(794)
CONVUM PRESSURE DISPLAY SWITCH MPS-71E-G-D5
Convum Parker PFYK-25-U Vacuum Suction Cups
MYOTOKY LDT.CVA-15HSA CONVUM VALVE
Parker Convum CEK27HSZC24PBLN Vacuum Pump Generator
Convum Vacuum Generator Pump CV10HSC
Convum Vacuum Generator Pump CCV10HSCK NEW
2 Convum Parker PFYK-25-SI Vacuum Suction Cups
PARKER generator CONVUM VACUUM PUMP PA244-RV3.5
MYOTOKU/CONVUM CV-10LS GENERATOR 10MM LOW VACUUM
MYOTOKU/CONVUM CV-10LS GENERATOR 10MM LOW VACUUM
CONVUM MVS-030-W NSFP MVS030W
CONVUM SENSOR,VACUUM FOR SPIN SD MPS-R3S5-GHA-D
DNS CONVUM?SENSOR,PRESSURE 2-AE-J0076 P3M5-GHA-D
CONVUM CVK-20HSABC-24B?L USPP CVK20HSABC24BL
DNS CONVUM SENSOR,DIGITAL SPI 2-AE-J0012 R3S5-GHA-D
Myotohu Convum MVS-030 Vacuum Switch
MYOTOKU/CONVUM CVF-1-10LS GENERATOR 1MM
CONVUM MPS-V2R-C NSFP MPSV2RC
CONVUM MPS-P1N-PC NSFP MPSP1NPC
DNS CONVUM PRESSURE SENSOR ASSY 2-AE-J0067 R3S5-GHA-D
CONVUM CYLINDER TKY-0-4.5X3
Convum Vacuum Switch CVA-D,CVA-10,CVA-V3B
Myotoky LTD.Model:CVA-10HR-VDN-24?B Convum Valve
4-Convum Vacuum Technology Valves CVK-15HSZC 24 VDC
MYOTOKU/CONVUM CVF-1-10HRAB/MV?S-030-AB VAC SENSOR
MYOTOKU CONVUM CVR Vacuum Switch
CONVUM CVF-2-05HS VACUUM SWITCH SOLENOID VALVE
CONVUM MPS-V2R-PGA NSPP MPSV2RPGA
Parker MPS Convum PRESSURE Switch P6N-PG(11)
Parker Convum CVX-0260-B-E0S-?DN PA244-RV3.5 Vacuum Pump
MYOTOKU/CONVUM VF-3 VACUUM FILTER
CONVUM MPS-V3RC-G-M VACUUM PRESSURE SENSOR
Parker Convum Vacuum LED Switch MPS-V2N-PC
Parker Convum CVX0260BE0SDNNA Vacume Pump PA244-RV3.5