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火花試驗機的應用匹配
日期：2024-12-15 02:53
瀏覽次數：3331
摘要：
火花試驗機的應用匹配
作者：深圳市杰帝實業有限公司
火花試驗機的應用匹配
AC Or DC?
交流還是直流?
Matching theSparkTester to the Application
火花試驗機的應用匹配
How to choose the best spark tester for your application: primary
Insulation﹐twinning﹐bunching﹐taping﹐cabling﹐jacketing or marking.
在以下不同的工序怎樣選擇合適的火花測試機﹕絕緣﹐束線﹐對絞﹐成纜﹐絕緣包帶﹐外被或印字
Spark testing has long been used on theprimaryinsulation line and at packaging﹐providingfirst and final insulation qualitychecks﹒ Increasingly﹐manufacturers are checking for defects prior toor after such interim processes as twinning﹐bunching﹐taping﹐cabling﹐jacketing and marking﹒Thefollowing is a discussion of spark tester selection andapplication﹒
火花測試用于單絕緣﹐包裝已有很長時間了﹐尤其是用于開始或*后的絕緣品質檢測。逐漸的﹐廠商在象對絞﹐束絞﹐包帶﹐成纜﹐外被和印字等中間工序之前或之後檢查產品的缺點。下面將討論火花測試機的選擇和應用。
Spark test equipment is classified by the typeoftest voltage applied to the product。Availabletypes include Alternating Current(AC)and Direct Current(DC).ACspark testers are of two types---thosethat operate at power mainsfrequencies (generally 50 or 60 Hz) andhigh-frequency types thatoperate at frequencies between 500 Hz and3 kHz﹒Impulse testers﹐which are no longer in common use﹐are not discussed.
火花測試設備是通過施加于產品的電壓種類來分類的﹐使用的電壓種類包括交流電壓和直流電壓。交流電壓火花測試機包括兩種型號---工作于電力基本頻率(通常為50或60赫茲)的工頻火花機和工作于頻率介于500到3千赫茲的高頻火花機。脈沖波形火花測試機已不常用﹐這里不予討論。
Advantages of ACSparkTesting
交流火花試驗機的優點
AC spark testers create a field of ionized air(ablue-colored glow called corona) around the product. The coronaiselectrically conductive and provides a good test even when thebeadchains are not making physical contact. Corona is caused inpart bythe AC voltage changing from positive to negative with eachcycle.For this reason, high frequency spark testers generate morecoronathan 60 cycle testers.
交流火花測試機使產品周圍的空氣電離(一種藍色的電暈)形成電場。這電暈是
可導電的,提供了一種良好的測試﹐即使當電極珠鏈沒有被連接到時。電暈是由于交流電在每個周期內由正向轉向負向時產生的。由于這些原因﹐高頻火花機產生的電暈比60赫茲的更多。
Also, a by-product of the corona is heat. Ifyouwere to leave a grounded cable stationary in anenergizedhigh-frequency electrode for a while, you would noticethat theinsulation is noticeably warmer where it made contact withthecorona field. This heating helps to break down weak spots inthedielectric that otherwise might pass through theelectrodeundetected, only to fail during a later spark orhipottest.
又由于﹐靠近電線制品的電暈是熱的。如果我們將一根接地電纜穩定放在施以高頻電極電壓的電極中一會兒﹐你將注意到與電暈有接觸的絕緣部分有明顯的變熱。這熱量幫助擊穿電線絕緣較薄的地方﹐否則線材通過電極而沒有被檢測到﹐結果在以后的火花測試和高壓絕緣試驗將會失效。
Disadvantages ofACSpark Testing
交流火花機的缺點
In wires with very weak insulation (suchastelecom and datacom wires having a foamed dielectric), theACvoltage ionizes the air inside the foam cells, reducingoveralldielectric strength of the insulation. The insulation maythenfail, damaging the product. This is particularly truewithhigh-frequency spark testers that should not be used withfoamedinsulation.
絕緣較薄的電線(如具有發泡絕緣的通信和網絡電纜)﹐交流電壓使發泡單元里的空氣電離﹐這將減少絕緣的介電強度。這絕緣將失效﹐*終將損壞這產品。因此高頻火花機不被應用于發泡絕緣是非常正確的。
When the capacitance of the product intheelectrode is very high, a leakage current forms.Becausecapacitance is more a function of the ratio of conductorsize toinsulation thickness than to overall size﹐productsthat produce high capacitance can include cables with largeconductors and thin insulation, small wires with very thindielectric or multiple conductors going through the sameelectrode(e.g., tape and ribbon cables).For safety reasons, thespark tester’s current output is limited to 4 to 6 milliamps. Whenthe leakage current reaches this level, there is no more availablesupply current to generate a greater test voltage. The maximumpossible voltage attainable with that product may not be highenough to provide a good test.
當在電極中的電線產品的電容特別高時﹐將形成泄漏電流。因為此電容是導體尺寸與絕緣厚度比值的函數﹐例如大導體薄絕緣電纜,或薄絕緣的有非常小介電常數的小電線或多根導體的電線,通過同樣的電極時將產生很高的電容(帶狀電纜)。為了**起見﹐火花機的電流輸出被限制在4~6毫安。當泄漏電流達到這水平時﹐火花機將再也不能有效輸出電流來產生高的測試電壓。對于某種電線﹐能達到的*大可能電壓將不夠提供很好的測試。
A dvantages of DC SparkTesting
直流火花機的好處
DC sparktestinggenerates practically no corona and no heat, and istherefore agentler test process, DC can be used on foamedinsulation and thininsulation.
DC technology hasnoproblem with capacitance. Very large wires and multipleconductorscan be tested with one power supply. DC spark testersare often usedin cabling operations, sometimes testing 25 twistedpairs within asingle electrode.
直流火花機幾乎不能產生電暈和熱量﹐因此它是一種輕微的測試方法﹐直流火花機可用于發泡和薄的絕緣。
直流火花機技朮對用于電容沒有問題。非常大的電線和多根導體的電線可以用一臺設備來測試。直流火花機常被用于成纜﹐有時在單個電極中測試25對的電纜。
Disadvantages ofDCSpark Testing
直流火花機的缺點
The productmustbe grounded! Thecenterconductor or shield should be grounded for reasons of safetyandefficacy.If the product isnotgrounded and a fault passes throughtheelectrode﹐the spark tester will count,butthe entire reel will become charged to high voltage andwillmaintain this potential until something discharges it.Subsequentfaults may not be detected because the center conductorwill benearly the same potential as the electrode, and detection circuits requiredifferentiation.
電線必須接地﹗因**和有效性原因﹐中央導體或屏蔽必須接地。如果未接地和有破點的電線通過電極時﹐火花機將計數﹐但是整卷將被充上高壓和保持這種電壓直到某種物體使它放電。由于中央的導體的電位幾乎與電極的電位相同,後面的缺限將不能被檢測出來.因為檢測電路要有電位差(譯者:電壓可以理解為電位差)。
A different test voltage must be used ascomparedwith AC (1.414xAC RMS Voltage=DC Peak voltage).This is notreally adisadvantage, but a difference in the way the two types ofvoltageare measured, AC is measured in RMS (root means squared)while Dcis measured as Peak Voltage.
同樣的測試,與交流電壓相比較﹐直流測試電壓數值是不同的(1.414 X有效值電壓=直流峰值電壓)。這不是一個真正的缺點﹐而是兩者的計量方式不同,交流電壓是以有效值來計量而直流電壓是以其峰值來計量的。
綜上所述，火花試驗機的應用匹配是根據所測試線材的種類來決定的。
綜上所述，火花試驗機的應用匹配是根據所測試線材的種類來決定的。
UL標準參考測試電壓：
1.額定電壓的10倍,但是*小不能小於1500V---即額定電壓在150V以下的,火花機電壓設定為1500V,額定電壓大於等於150V的,火花機電壓就設定為額定電壓的10倍;
2.如果額定電壓沒有規定,則火花機電壓設定為3000V;
3.對於額定電壓超過1000V的,則火花機電壓設定為額定電壓的2倍,但是*小不能小於10000V---即額定電壓在5KV以下的,火花機電壓設定為10000V,額定電壓大於等於5KV的,火花機電壓就設定為額定電壓的2
倍; 4.符合UL758 表3-2,額定電壓為300V的線材,火花機電壓設定為1500V;
倍; 4.符合UL758 表3-2,額定電壓為300V的線材,火花機電壓設定為1500V;
5.符合UL758 表3-2,額定電壓為600V的線材,火花機電壓設定為2000V;
火花試驗機的應用匹配
火花試驗機的應用匹配
火花試驗機的應用匹配
火花試驗機的應用匹配
