公司主營產(chǎn)品圖展示
產(chǎn)品優(yōu)勢
1：國外專業(yè)的供貨渠道，具有價(jià)格優(yōu)勢
2：產(chǎn)品質(zhì)量保證，讓您售后無憂
3：全國快遞包郵
4：一對一服務(wù)
產(chǎn)品詳情介紹
ABB 64844-004 3-064843-002接口過程編程板
在供電系統(tǒng)中，接地系統(tǒng)定義導(dǎo)體的相對電勢地球?qū)щ姳砻?。接地的選擇
系統(tǒng)對安全和電磁有影響電源的兼容性。請注意，法規(guī)對于接地系統(tǒng)不同的國家。
保護(hù)接地（PE）連接確保導(dǎo)電表面的電位與地面，以避免電擊風(fēng)險(xiǎn)如果有人接觸到絕緣故障的設(shè)備發(fā)生。它確保在絕緣故障（“短路電路”），電流非常大，將觸發(fā)過電壓
斷開電源的電流保護(hù)裝置（保險(xiǎn)絲、斷路器）。功能性接地連接的用途不同于提供防電擊保護(hù)。相比之下保護(hù)接地連接，功能性接地連接在設(shè)備正常運(yùn)行期間可能攜帶電流。
設(shè)備可能需要功能性接地連接如浪涌抑制和電磁干擾濾波器、某些類型的天線和各種測量儀器。通常，保護(hù)接地也用作功能性地球，盡管在某些情況下需要小心。國際標(biāo)準(zhǔn)IEC 60364區(qū)分了三個(gè)使用雙字母代碼的接地裝置系列TN、TT和IT。
第一個(gè)字母表示接地和電源設(shè)備（發(fā)電機(jī)或變壓器）：
T： 點(diǎn)與地面的直接連接（拉丁語：terra）；
一： 沒有任何點(diǎn)與接地（絕緣）相連，除非也許是通過高阻抗。
第二個(gè)字母表示接地和所提供的電氣設(shè)備：T： 點(diǎn)與地的直接連接N： 直接連接至安裝起點(diǎn)的中性點(diǎn)，連接到接地TN系統(tǒng)在TN接地系統(tǒng)中，發(fā)電機(jī)中的一個(gè)點(diǎn)或變壓器接地，通常為星點(diǎn)在三相系統(tǒng)中。電氣設(shè)備主體為通過變壓器處的接地連接與大地相連。基本上有三種不同類型的TN系統(tǒng)區(qū)別：TN-S、TN-C、TNCS。
TN系統(tǒng)可由MCB（微型電路）保護(hù)斷路器）。系統(tǒng)中的任何短路都會(huì)產(chǎn)生足夠的使MCB跳閘的能量。
TT系統(tǒng)在TT接地系統(tǒng)中耗電元件由本地接地連接提供，獨(dú)立于發(fā)電機(jī)的任何接地連接。如果發(fā)生接地故障，則故障路徑的電阻會(huì)返回電源電壓過高，分支電路電流過大操作保護(hù)（熔斷保險(xiǎn)絲或使斷路器跳閘）。
在這種情況下，安裝剩余電流檢測器（RCD）檢測泄漏到地面的電流并中斷電路
In electricity supply systems, an earthing system defines
the electrical potential of the conductors relative to that
of the Earth’s conductive surface. The choice of earthing
system has implications for the safety and electromagnetic
compatibility of the power supply. Note that regulations
for earthing (grounding) systems vary considerably among
different countries.
A protective earth (PE) connection ensures that all exposed
conductive surfaces are at the same electrical potential as
the surface of the earth, to avoid the risk of electrical shock
if a person touches a device in which an insulation fault has
occurred. It ensures in case of an insulation fault (a “short
circuit”), a very high current flows, which will trigger an over
current protection device (fuse, circuit breaker) that disconnects the power supply.
A functional earth connection serves a purpose other than
providing protection against electrical shock. In contrast to a
protective earth connection, a functional earth connection
may carry a current during the normal operation of a device.
Functional earth connections may be required by devices
such as surge suppression and electromagnetic interference
filters, some types of antennas and various measurement
instruments. Generally the protective earth is also used as a
functional earth, though this requires care in some situations.The international standard IEC 60364 distinguishes three
families of earthing arrangements, using the two-letter codes
TN, TT and IT.
The first letter indicates the connection between earth and
the power-supply equipment (generator or transformer):
T: direct connection of a point with earth (Latin: terra);
I: no point is connected with earth (insulation), except
perhaps via a high impedance.
The second letter indicates the connection between earth and
the electrical device being supplied:
T: direct connection of a point with earth
N: direct connection to neutral at the origin of installation,
which is connected to the earth
TN-system In a TN earthing system, one of the points in the generator or transformer is connected with earth, usually the star point in a three-phase system. The body of the electrical device is connected with earth via this earth connection at the transformer. Basically three different types of TN systems are distinguished: TN-S, TN-C, TN-C-S. TN systems can be protected by a MCB (miniature circuit breaker). Any short circuit in the system will create sufficient energy to trip the MCB. TT-system In a TT earthing system, the protective earth connection of the consumer is provided by a local connection to earth, independent of any earth connection at the generator. In case of an earth fault the resistance of the fault path back to the supply is too high for the branch circuit over current protection to operate (blow a fuse or trip a circuit breaker). In such case a residual current detector (RCD) is installed to detect the current leaking to ground and interrupt the circuit
