1. List the requirements and regulations of RCD as recommended by CoP of the RCCB under test .
2. Why RCD is still required for appliances supplied from a socket outlets as shock protection when the equipment is connected with a protective conductor?
3. Will there be any effect on the testing result if there exist a DC component in the circuit? If yes, under what condition will a DC component exist in an AC circuit?
唔識做呢3條~~
唔該幫幫手~~
關於電..(20分)英文作答
2009-03-19 8:05 am
回答 (2)
2009-03-23 10:40 pm
1. The function test of RCCB and its passing criteria:
(i)RCCB should be checked by RCD tester.
(ii)Test at 50% x IDn, the RCCB should not be open > 2s. (IDn means the rated tripping current, i.e. 30mA)
(iii)The maximum break time of RCCB (to IEC61008) at IDn is 0.3s
(iv)The built-in test button of RCDs should also be tested for proper functioning.
2. RCD for sockets final circuit is a statutory requirement. All socket outlets shall be protected by 30mA RCD, you could find this statement in COP. The main point is the RCD could ensure no more than 30mA residual current flow more than 0.3s through the human body as kind of the protection. Using normal protection cannot ensure this point.
3. DC component in a circuit means the resistor? It always exist in all electrical appliances, no harm to the AC circuits. But if you said there are DC components in AC voltage / supply, there shall be harmonics or the voltage is flow up. This will cause unnecessary high volage to the ground (i.e. 0V). The high voltage may cause arcing flash over and high touch voltage during fault.
(i)RCCB should be checked by RCD tester.
(ii)Test at 50% x IDn, the RCCB should not be open > 2s. (IDn means the rated tripping current, i.e. 30mA)
(iii)The maximum break time of RCCB (to IEC61008) at IDn is 0.3s
(iv)The built-in test button of RCDs should also be tested for proper functioning.
2. RCD for sockets final circuit is a statutory requirement. All socket outlets shall be protected by 30mA RCD, you could find this statement in COP. The main point is the RCD could ensure no more than 30mA residual current flow more than 0.3s through the human body as kind of the protection. Using normal protection cannot ensure this point.
3. DC component in a circuit means the resistor? It always exist in all electrical appliances, no harm to the AC circuits. But if you said there are DC components in AC voltage / supply, there shall be harmonics or the voltage is flow up. This will cause unnecessary high volage to the ground (i.e. 0V). The high voltage may cause arcing flash over and high touch voltage during fault.
2009-03-29 7:14 am
我懷疑MartinPun既答案係Copy的,,
就憑文字大小,,顏色,,
我已認得出這答案是何福良先生提供的,,
http://hk.knowledge.yahoo.com/question/question?qid=7008101301851
上述網址的知識我早已Print出來作參考,,
請檢點 ! !
2009-03-28 23:14:28 補充：
我懷疑MartinPun既答案係Copy的,,
就憑文字大小,,顏色,,
我已認得出這答案是何福良先生提供的,,
http://hk.knowledge.yahoo.com/question/question?qid=7008101301851
上述網址的知識我早已Print出來作參考,,
請檢點 ! !
就憑文字大小,,顏色,,
我已認得出這答案是何福良先生提供的,,
http://hk.knowledge.yahoo.com/question/question?qid=7008101301851
上述網址的知識我早已Print出來作參考,,
請檢點 ! !
2009-03-28 23:14:28 補充：
我懷疑MartinPun既答案係Copy的,,
就憑文字大小,,顏色,,
我已認得出這答案是何福良先生提供的,,
http://hk.knowledge.yahoo.com/question/question?qid=7008101301851
上述網址的知識我早已Print出來作參考,,
請檢點 ! !
收錄日期: 2021-04-13 21:59:14
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090319000051KK00013