TU810V1 3BSE013230R1工控模塊系統(tǒng)備件
規(guī)定的大氣混合物。為了設(shè)計(jì)有效的本質(zhì)安全系統(tǒng)，必須限制進(jìn)入危險(xiǎn)區(qū)域的能源。對(duì)于電子控制，通過(guò)控制可能進(jìn)入危險(xiǎn)區(qū)域的電壓和電流來(lái)實(shí)現(xiàn)能量限制。此外，控制裝置中儲(chǔ)存的電能被限制在不能引起給定大氣點(diǎn)燃的水平。本質(zhì)安全系統(tǒng)克服了“防爆”系統(tǒng)的缺點(diǎn)，通過(guò)在安全區(qū)域正確安裝本質(zhì)安全齊納二極管屏障，實(shí)際上消除了爆炸的可能性。本質(zhì)安全齊納二極管安全柵必須安裝在電源線、負(fù)載供應(yīng)線以及使用5500系列電流源（PNP）開(kāi)路集電極時(shí)的信號(hào)返回線中。危險(xiǎn)場(chǎng)所概述（有關(guān)完整定義，請(qǐng)參考國(guó)家電氣規(guī)范出版物NFPA第70-78號(hào)）I類(lèi)場(chǎng)所，其中空氣中存在或可能存在足以產(chǎn)生爆炸性或可燃性混合物的易燃?xì)怏w或蒸汽。由于存在可燃性粉塵而具有危險(xiǎn)性的II類(lèi)場(chǎng)所。III類(lèi)位置，由于存在易點(diǎn)燃的纖維或飛邊而具有危險(xiǎn)性，但此類(lèi)纖維或飛線不可能懸浮在足以產(chǎn)生可燃混合物的空氣濃度中。在正常操作條件下，空氣中存在危險(xiǎn)濃度的I類(lèi)場(chǎng)所連續(xù)、間歇或周期性存在。第2部分：處理、處理或使用危險(xiǎn)濃度的場(chǎng)所，但通常位于封閉容器或封閉系統(tǒng)內(nèi)，只有在意外破裂或故障時(shí)，這些場(chǎng)所才能逃離。A組含乙炔的環(huán)境。B組含有氫氣或具有同等危險(xiǎn)的氣體或蒸汽（如人造氣體）的環(huán)境。C組含有乙醚蒸汽、乙烯或環(huán)丙烷的大氣。D組：含有汽油、己烷、石腦油、汽油、丁烷、丙烷、酒精、丙酮、苯甲醇、漆溶劑蒸汽或天然氣的大氣。
specified atmospheric mixture. To design an effective Intrinsically Safe system, energy sources that enter the hazardous area must be limited. For electronic controls, energy limiting is accomplished by controlling the voltages and currents that may enter the hazardous area. In addition, stored electrical energy in the controls is limited to levels that cannot cause ignition of a given atmosphere. An Intrinsically Safe system overcomes the shortcomings of the “explosion-proof ” system and virtually eliminates the probability of explosion by properly installing Intrinsic Safety Zener Diode Barriers in the safe area. Intrinsic Safety Zener Diode Barriers must be installed in the power supply line, the load supply line and when using the current source (PNP) open collector of the Series 5500, in the signal return line. Summary of Hazardous Locations (For full and complete definitions, consult the National Electric Code publication NFPA No. 70--78.) Class I Locations in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures. Class II Locations which are hazardous because of the presence of combustible dust. Class III Locations which are hazardous because of the presence of easily ignitable fibers or flyings, but in which such fibers or flyings are not likely to be suspended in air concentrations sufficient to produce ignitable mixtures. Division I Locations which are hazardous concentrations in the air exist continuously, intermittently, or periodically under normal operating conditions. Division 2 Locations which are hazardous concentrations are handled, processed, or used but are normally within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown. Group A Atmospheres containing acetylene. Group B Atmospheres containing hydrogen, or gases or vapors of equivalent hazard, such as manufactured gas. Group C Atmospheres containing ethyl-ether vapors, ethylene, or cyclo-propane. Group D Atmospheres containing gasoline, hexane, naptha, benzine, butane, propane, alcohol, acetone, benzol, laquer solvent vapors, or natural gas.
