bs 50999:1992

foreword  前言

this britishi standard has been prepared under the direction of the cable and insulation standards policy committee and supersedes bs 5099:1974 which is withdrawn..

本標準是英國關於電線電纜行業(yè)的標準，取代bs 5099:1974

this edition of bs 5099 introduces a clause on calibration frequency, together with an associated annex on the procedure for checking the efficacy of the method of spark testing.

此版本的bs 5099在附件裏增添了火花試機的校準週期以及校準的方法和程式。

this british standard specifies spark testing of a wide range of cables, and , in as far as it is applicable, is equivalent to the spark testing specified in hd 21.2 and hd 22.2 for low voltage cables.

這個版本的bs 5099對電線電纜的絕緣火花試驗作了很全面的說明，在很長時間內都是很適用的，在低壓電線的火花測試與hd 21.2和hd 22.2是一樣的。

compliance with a british standard does not of itself confer immunity from legal obligations.

bs標準本身不能作為產品免檢的法律依據。

 specification  規(guī)格說明

1 scope  範圍

this british standard specifies requirements and test methods for a.c,d,c,high frequency and pulsed wave-form spark testing of the insulation and sheath of electric cables, the use of high frequency and pulsed wave-form testers is limited to cables rated less than 0.6/1kv,unless referred to in the cable specification.

這個標準是英國關於ac、dc、和高頻以及脈衝電壓對絕緣電線和護套的火花測試標準。高頻或脈衝火花機是用於檢測額定電壓在0.6或1kv以下的電線。

2.references 參考

2.1 normative references  標準參考

this british standard incorporates, by reference, provisions from specific editions of other publications. these normative references are cited at the appropriate points in the text and the publications are listed on the inside back cover. subsequent amendments to , or revisions of , any of these publications apply to this standard only when incorporated in it by updating or revision.

2.2 informative references  標準的提供

this british standard refers to other publications that provide information or guidance. editions of these publications current at the time of issue of this standard are listed are listed on inside back cover, but reference should be made to the latest editions.

3 application  應用

the spark test which is specified in this standard shall be applied at the stages

of manufacture indicated by the cable specification.

這個標準裏關於火花測試的內容對於電線電纜製造業(yè)是很有用的。

note1. the test clauses of the appropriate cable specifications give details of the component to which spark testing is applicable.根據電線的不同規(guī)格來選擇適當的測試方式。

note2.for guidance on the use of spark testing machines, see annex a.   火花機的使用見附錄a

4．high voltage source  高壓電源

4.1 general  普通的

to avoid the risk of electrical shock to personnel, for all types of voltage source the output shall be limited to less than 10ma r.m.s or equivalent. the high voltage source shall be supplied in one of the following forms.

為了避免人員觸及高壓而造成的危險，所有的輸出高壓電源的電流必須≤10ma.高壓電源必須符合下面某一種：

a)    alternating current of approximay sine wace-form at a frequency of 40hz to 62hz.

a) 交流電電源頻率為40hz-62hz，電壓波形應近似正弦波。

b)    direct current with the positive pole earthed and the negative pole connected to the test electrode by means of a low capacitance unscreened lead.

the peak to peak value of ripple on the d.c. output voltage shall not exceed 5% of the d.c. voltage.

b)直流電源的正極接地，負極由一根低電容的非遮罩電線與試驗電極連接。電源輸出電壓應為脈動因數不大於5%的直流電壓。

c)    high frequency current of approximay sine wave-form at frequency of 1khz to 1000khz. 高頻電源頻率通常為1khz-1000khz之間，電壓波形近似正弦波。

d)    impulsed current generated from a voltage wave-form consisting of a sharp rise pulse followed by a highly damped wave train.

the sharp rise of the impulse wave front shall reach 90% of the specified peak value in less than 20us. fluctuations of the actual peak value, due to variations of input power into the generator, shall not exceed±2% of the specified peak value. the peak value shall not show more than 5% reduction in the event of an increase of capacitance load of 50pf,during the operation, from an initial load of 25pf between electrode and instrument ground. the pulse duration, including the damped portion of the wave, shall be between 40us and 50us. the pulse repetition tate of the electrode shall be  a minimum of 170 pulses per second. visible or audible corona shall be evident in the electrode structure when operating at the specified voltage

脈衝波的波頭在20us內將會突漲90%。那些變化是由於輸入脈衝發(fā)生器的電壓所引起的。其波動不應超過每刻度峰值電壓的±2%。在運行期間，電極的電容負載從25pf增到50pf.其峰值的增長應在5%以內。在脈衝週期的波形衰減應在40us與50us之間。電極每一的迴圈脈衝必須大於170次以上。運行的時候，在電極周圍可以明顯的看見有一束光環(huán)。

4.2 voltage monitoring equipment 電壓檢測設備

4.2.1 for a.c, d.c. and high frequency sources the electrode to earth potential difference shall be displayed on a meter either by connection direct to the output terminals of the high voltage source or by any suitable arrangerment which gives a result±5% of the drect reading. the meter shall be calibrated to read d.c. or a.c. (r.m.s) as appropriate and shall conform to a standard not lower than that specified for class 1 instruments in bs89:part 1: 1990 and part 2: 1990.

火花機對地的電位差應由火花機的試驗電壓儀錶顯示，該表既可直接接到高壓電源輸出端，也可通過任何其他合適連接方法連接，但是其顯示值誤差應在±5%範圍內。

4.2.2 for an impulse source there shall be a peak reading instrument voltmeter connected directly to the electrode head, indicating continually the potential of the electrode with or without a grounded test wire in the chamber. the peak reading voltmeter shall show full deflection at a peak value not exceeding 25kv and shall have an accuracy of±3% of the specified operating value。this meter shall be capable of maintaining this accuracy for an adequate period, and the calibration frequency set accordingly.

脈衝火花機，電壓表直接接在試驗電極上，顯示的是測試電線沒有接地的情況下的峰值電壓。電壓表顯示的zui高峰值是25kv,誤差為每刻度的±3%以內。這個表應能保證其準確度在一定內時間都不變，其校準週期同火花機。

the impulse test equipment shall be calibrated by means of a peak detecting electronic voltmeter connected directly between the electrode head and ground. the impulse generator shall be energized and the voltage control of the impulse generator shall be adjusted until the reading on the calibration voltmeter is the specified potential,at which point the reading on the instrument voltmeter shall be observed  and recorded; this calibration shall be repeated at each specified peak potential. the pulse wave-form shall be monitored by means of an oscilloscope connected to the electrode head at suitable test points.

脈衝火花機的校準是把數位電壓表直接接在測試電極和地之間。調節(jié)脈衝發(fā)生器直到輸出的電壓與電壓表上的電壓一致為止。每個刻度都要觀察和記錄並要重複進行。脈衝波的波形是通過接在測試電極頭上的示波器來觀察。

note:calibration may be accomplished without a test wire in the electrode head, in which case the voltage control on the impulse generator may require different setting for each cable size in order to give the desired reading on the instrument voltmeter; or the calibration may be made with a load of 20pf to 60pf. the equipment may also be calibrated against an oscilloscope with a calibrated and compensated attenuator. the chosen method should have an accuracy of±2%.

注釋：火花機的校準必須在試驗電極沒有電線或電纜通過的情況下進行。校準所用的示波器和電源衰減器也必須先校準，選擇的測試方法的誤差應在±2%以內。

5 test voltage  測試電壓值

5.1 contact electrode 接觸式電極

5.1.1 general 常規(guī)

the high voltage supply to the test electrode shall be either alternating current, direct current, high frequency current or impulsed current as specified in 4.1.

通常採用的測試高壓電源有交流、直流、高頻和脈衝。在4.1中有詳細介紹。

for all types of testing, the conductor of the core under test, or the conductor, metallic sheath, screen or armour underlying the non-metallic sheath to be tested ,shall be continuously earthed .金屬護套導線，

適合於所有類型的電線測試，測試時金屬線芯、金屬遮罩部分或金屬鎧裝層以及金屬護套都必須連續(xù)的良好接地。

5.1.2 insulation  絕緣

spark test voltage values given by the potential difference between the test electrode and the conductor of the core or cable under test shall be specified in the cable standard.

火花試驗時，電極與被測試電線或電纜之間的電位差的值在電線標準中有明確規(guī)定。

測試電壓參考表
5.1.3 insulation/sheath   絕緣/護套

when spark testing of a combination of insulation/sheath is specified in the relevant cable standard, it shall be carried out using one of the voltage sources specified in 4.1 at the appropriate voltage given as follows:

絕緣護套的火花測試標準，要按照4.1裏規(guī)定的電源種類和電壓標準：

a)      a.c.: at 6kv per millimetre of the combined tabulated radial thickness of insulation and sheath, up to a maximum voltage of 25kv;

 交流電源測試時，每一毫米絕緣厚度的護套要求6kv的電壓，zui高為25kv。

b)      d.c.and impulse: at 9kv per millimetre of the combined tabulated radial thickness of insulation and sheath, up to a maximum voltage of 38kv for d.c.and 23kv for impulse;

使用直流電源或脈衝測試時，每一毫米絕緣厚度的護套要求9kv的電壓，直流zui高為38kv，脈衝zui高為25kv.

c)      h.f.: at 7kv per millimetre of the combined tabulated radial thickness of insulation and sheath, up to a maximum voltage of 14kv.

使用高頻電源測試時，每一毫米的絕緣厚度要求7kv的電壓，zui高為14kv.

5.1.4 sheath 護套

when spark testing of sheath of thickness greater than 0.5mm is specified in the relevant cable standard it shall be carried out using one of the voltage sources specified in 4.1 at the appropriate voltage given as follows:

 在絕緣厚度大於0.5mm的護套電纜測試在電線的標準中應有詳細的規(guī)定，適當的選擇4.1中的電源進行測試。

a)    a.c.: at 6kv per millimetre of tabulated radial thickness of sheath, up to a maximum voltage of 25kv;

 交流測試時，每毫米厚度的護套需要6kv的電壓測試，zui高電壓是25kv

b)    d.c.and impulse: at 9kv per millimetre of tabulated radial thickness of sheath, up to a maximum voltage of 38kvfor d.c.and 23kv for impulse;

直流和脈衝測試時，每毫米厚度的護套需要9kv的電壓，直流的zui高電壓是38kv,脈衝的zui高電壓是23kv;

c)    h.f.: at 7kv per millimetre of tabulated radial thickness of tabulated radial thickness of sheath,upto a maximum voltage of 10.5kv.

 高頻測試時，每毫米厚度的護套的電壓是7kv，zui高測試電壓是10.5kv.

note. for sheath thickness below 0.5mm,the test voltage should be the subject of agreement between the purchaser and the manufacturer.

注意：當護套的厚度小於0.5mm時，測試電壓應當由製造商和購買者協(xié)調。

5.2 non-contact electrode  非接觸式電極

the supply to the test electrode shall be direct current only,as defined in 4.1b. the conductor of the core or the metallic layer under the sheath shall be continuously earthed and the potential difference between the electrode and the conductor or the metallic layer shall be 18kv.

供給測試電極的電源只能是直流，直流定義在4.1裏有詳細敍述。被測試電線的金屬線芯或金屬遮罩層必須接地，測試電極與被測電線或金屬層的電位差是18kv。

6 design of electrode  電極的設計

6.1 contact electrode  接觸式電極

the contact electrode shall be of metallic construction and its length shall be such that every point of the insulated conductor or non-metallic covering under test is in the electrode for a time not less than the following:

接觸式電極為金屬材料做製成。電極的有效長度應使被測產品絕緣上每點通過電極的時間不小於以下標準：

a)    with a.c. supply to the electrode:0.05s;  交流電源測試時為0.05s.

note 1. this time represents a maximum through-put speed of 1.2 m/min per millimetre of electrode.

注2：這個時間表示被測試產品穿過每毫米長電極的zui大速度為1.2m/min.

b)    with d.c. supply to the electrode: 0.001s;直流電源測試時為0.001s.

note 2. this time represents a maximum through-put speed of 60m/min per millimetre of electrode.

注2：這個時間表示被測試產品穿過每毫米長電極的zui大速度為60m/min.

c)    with h.f. supply to the electrode: 0.001s; 高頻電源測試時為0.001s.

note 3. this time represents a maximum through-put speed of 60m/min per millimetre of electrode.

注3：這個時間表示被測試產品穿過每毫米長電極的zui大速為60m/min.

d)    with impulse supply to the electrode:0.02s. 脈衝電源測試時為0.02s.

note 4. this time represents a maximum through-put speed of 3.0m/min per millimetre of electrode.

注4：這個時間表示被測試產品穿過每毫米長電極的zui大速度為3.0m/min.

the electrode in direct contact with the cable under test shall not consist of mercury or of any other material in the fluid state.

與電線電纜接觸的電極不允許由水銀或其他任何液體所組成。

6.2 non-contact electrode  非接觸式電極

the non-contact electrode shall consist of a cylindrical metal tube whose internal diameter is nominally 13mm.

the length of the electrodes shall be such that every point of the core or cable under test is in the electrode for not less than 0.001s.

非接觸式電極是由內徑為13mm的金屬管制成的。

電極的有效長度應使被測產品絕緣上每點通過電極的時間不小於0.001s.

note. this time represents a maximum through-put speed of 60m/min per millimetre of electrode.

注：這個時間表示被測產品穿過每毫米長電極的zui大速度為60m/min.

the core or cable under test shall be guided by any suitable means through the centre of the test electrode and be maintained in that position without undue deviation for the duration of the test run. the maximum recommended core or cable size that should be tested by the non-contact system is 3.0mm diameter overall.

電線或電纜通過適當的引導方式穿過試驗電極中心，並保證在運行期間能順利通過而不受影響，在非接觸式電極測試時，被測試電線或電纜的的zui大直徑為3.0mm。

7 fault indicator  破壞指示器

there shall be a failure detection circuit to give a visible or audible indication of insulation/sheath failure. the fault detector shall be arranged to operate a digital display counter such that one count per discrete fault is registered. the counter shall maintain the indication until the indication is manually cancelled.

擊穿指示器由數字計數器和聲響報警器組成，能對每次擊穿都能記錄和報警。擊穿指示器應能保持其記數，直至下一個擊穿被記錄或指示器被人工重定。

8 sensitivity  靈敏度

8.1 a.c., h.f. and d.c. electrode supply  交流、高頻、直流電源電極

the sensitivity of the spark testing apparatus shall be such that the detector will operate when an artificial fault device, described in annex b, is connected between the electrode and earth. the methods for assessing the sensitivity apply for a.c. and h.f.as specified in b.1 and for d.c.as specified in b.2.

火花試驗機的靈敏度測試需要在電極和地之間連接一個人工擊穿裝置，詳見附錄b，交流和高頻的靈敏讀測試在b.1中，直流和脈衝的靈敏度測試在b.2中。

8.2 impulse wave-form electrode supply  脈衝電源電極

the detection circuit shall be sufficiently sensitive to indicate a fault when the electrode is arced to ground through a 0.5 mω resistor and shall be capable of detecting a fault which lasts for the duration of only one impulse.

報警電路的靈敏度要十分的高，當電極電對地電阻達到0.5 mω形成電弧時，電路必須發(fā)出報警信號。並且在一個脈衝只發(fā)出一個錯誤信號。

9 calibration frequency  校準的週期

note. the efficacy test refered to in note 3 of clause 3 should be carried out upon initial installation of the equipment or upon any extension to the range of core or cable to be tested (see c.2.1).

9.1 the voltage calibration specified in 4.2.1 and 4.2.2 shall be carried out at least once a year, and after any repairs or major adjustments to the equipment.

電壓的校準見4.2.1和4.2.2。每一年必須校準一次，在大修或較大調整後，也應進行校準。

9.2 the sensitivity test specified in clause 8 shall be carried out at least once a year, and after any repairs or major adjustments to the equipment.

靈敏度的測試見第8部分，在大修或較大程度調整後，也應進行校準。

annexes  附錄

annex a (informative)   附錄a

guidance on the use of spark testing machines  火花機使用指導

it is recommended that, when spark testing is being carried out, the following precautions should be observed by the user.

火花機在使用的過程中，操作人員必須注意以下事項：

a)    access to electrode systems. to avoid the risk of operator shock when access is desired to the electrode systems, it is advisable to check regularly that the automatic switch- off mechanisms on the shielded enclosure for the electrodes are functioning correctly.

接觸電極。為了避免工作人員接觸到高壓電極而造成觸電事故，所以在高壓電極外部防護欄上必須裝置一個安全保護開關。

b)    conductor earthing. unless the conductor,metallic sheath,screen or armour underlying the ono-metallic covering under test is effectively and continuously earthed, faults may not be located. continuous earthing or other suitable means should be provided for the prevention of electrical shock.

導線要接地。如果導線的金屬線芯、金屬護套、金屬遮罩部分或鎧裝層沒有接地，那麼破壞點有可能無法檢測出來。直接接地或通過其他方式等效接地以防止遭受電擊。

c)    leakage currents. precautions are necessary to ensure the satisfactory operation of spark testing equipment by restricting operation of spark testing equipment by restricting leakage currents to a minimum level, e.g.by removing surface moisture from the core or cable under test before it enters the spark testing electrode.

漏電流。為了確保火花機能正常高性能的使用，所以在被測電線進入火花檢測之前必須除去外部的水分，以減小火花機的漏電流。

d)    charge removal. a length of core or cable which has been subjected to d.c. spark testing may retain a high potential static charge for a certain period after the test. to obviate the possibility of operator shock, care should be taken to ensure that a means of removing the charge from the cable surface is provided, e.g. by allowing the core or cable to run over or through an earthed metallic electrode immediay on emerging from the test electrode.

消除電荷。在使用直流火花機測試時，電線或電纜在測試後其表面有短暫的很高的靜電。為了防止操作人員被潛在的靜電傷害，應該除去電線或電纜表面的靜電，例如，用一根接地的金屬物在電線離開測試電極的時候立即與它接觸。

annex b (normative) 附錄b

methods for assessing the sensitivity of the spark test apparatus

火花機靈敏度的檢定方法

b.1 a.c. and h.f. electrode supply  b.1 交流和高頻電源

the no-load electrode voltage shall be set initially at 3kv(r.m.s) and when the artificial fault device is connected to the electrode, with the spark gap temporarily short-circuited, the steady state current shall not exceed 600ua. in order to limit the current to a suitable value an impedance may be added in series with the artificial fault device.為了將穩(wěn)態(tài)電流限制在適當的數值範圍內，可以串聯(lián)一附加電阻。

將火花機電極的空載電壓調到3kv，在此電壓下，當人工擊穿裝置接入後。其火花間隙短路狀態(tài)下的穩(wěn)態(tài)電流不超過600ua.

for the given electrode voltage of 3kv(r.m.s.),the spark gap shall consist of a metal plate and a needle point. the distance between them shall be 0.25±0.05mm. this gap shall be maintained for a period of 0.025s at least one every second.

在電極電壓調到3k的情況下，人工擊穿裝置中的火花間隙應由作相對旋轉運動的一塊金屬板和一個金屬針組成，在每秒鐘內金屬板與金屬針有一次距離為0.25±0.05mm，持續(xù)時間為0.025s的接觸。

the minimum requirement for sensitivity shall be such that a succession of not less than 20 breakdowns of the spark gap shall cause the fault indicator to register neither more nor less than one cunt per breakdown when the spark gap is open and is of the length shown above, with the current limiting impedance in series with the gap.

在zui底靈敏度測試的時候，應先接入上述要求的人工擊穿裝置，啟動人工擊穿裝置，使金屬板與金屬針間的火花間隙被連續(xù)擊穿20次，要求火花試驗機的擊穿計數器應記錄20次，對每次擊穿都應準確無誤地計數，不應多計也不應少計。

when compliance with the minimum requirement of sensitivity of the detector has been thus determined, the added impedance,if any,shall be short-circuited. a fault-free length of cable or core shall be in-serted into the electrode or a high voltage capacitor having the equivalent capacitance shall be increased across the gap and the electrode voltage shall be increased to the maximum required test potential. the test shall then be repeated with the sensitivity adjusted as necessary in order to establish that 20 further breakdowns of the spark gap cause the fault indicator to register neither more nor less than one count per breakdown.

zui低靈敏度符合要求後，將附加電阻短接（如果有附加電阻）。在電極間放入一段沒有缺陷的被測試電線，或在人工擊穿裝置的金屬板和金屬針間並上一個與被測試電線具有相同電容值 的高壓電容器，將電極電壓調到所需測試的zui高電壓，旋轉上述人工擊穿裝置，持續(xù)進行20次，火花機擊穿指示器應正確的記錄每一次擊穿，不應多計也不應少計。

note 1. to avoid  damage to the spark gap electrodes used at the lower voltage, the higher voltage test may be carled carried out using a separate but similar spark gap electrode assembly.

each test shall be carried out using a new needle and each needle shall be discarded after a maximum of 60 repetitive sparks.

每次試驗應更換新針，而且根針zui多使用了60次重複的火花試驗後就必須丟棄。

note 2. a suitable type of needle for use in this artificial fault device is given in annex d.

注釋2：人工擊穿裝置中所使用的針的型號的規(guī)定見附錄d。

b.2 d.c. electrode supply  直流高壓電源

the no-load electrode voltage shall be set initially at 5kv d.c.and when the artificial fault device is connected to the electrode, with the spark gap temporarily short-circuited,the steady state current shall not exceed 600ua.in order to limit the current to a suitable value,an impedance may be added in series with the artificial device.

在無負載情況下，將試驗電極電壓調到直流5kv，當人工擊穿裝置接入後，其火花間隙短路狀態(tài)下的穩(wěn)態(tài)電流不應超過600ua.為了穩(wěn)態(tài)電流控制在適當的數值範圍內，可以串聯(lián)一附加電阻。

for a given electrode voltage of 5kv d.c.,the spark gap shall consist of a metal plate and a needle point. the distance between them shall be 0.25±0.05mm. this gap shall be maintained for a period of 0.005s at least once every second. the needle point shall be negative with respect to the metal plate.

將試驗電極電壓調到直流5kv.接入人工擊穿裝置。人工擊穿裝置中的火花間隙應由作相對旋轉運動的一塊金屬板和一個金屬針組成，在每秒鐘內金屬板與金屬針尖有一次距離為0.25±0.05mm，持續(xù)時間為0.005s的接觸。針尖應為負極，金屬板應為正極。

the minimum requirement for sensitivity shall be such that a succession of not less than 20 breakdowns of the spark gap shall cause the fault indicator to register neither more nor less than one count per breakdown when the spark gap is open and of the length shown above, with the current limiting impedance in series with the gap.

在zui底靈敏度測試的時候，應先接入上述要求的人工擊穿裝置，，啟動人工擊穿裝置，使金屬板與金屬針間的火花間隙被連續(xù)擊穿20次，要求火花試驗機的擊穿計數器應記錄20次，對每次擊穿都應準確無誤地計數，不應多計也不應少計。

compliance with the minimum requirement of sensitivity of the detector having been thus determined,the adeed impedance,if any,shall then be increased to the maximum required test potential and the test repeated in order to establish that 20 further breakdowns of the spark gap shall cause the fault indicator to register neither more nor less than one count per breakdown.

zui低靈敏度符合要求後，將附加電阻短接（如果有附加電阻）。將電極電壓調到所需測試的zui高電壓，旋轉上述人工擊穿裝置，持續(xù)進行20次，火花機擊穿指示器應正確的記錄每一次擊穿，不應多計也不應少計。

note 1. to avoid damage to the spark gap electrodes used at the lower voltages,the higher voltage test may be carried out using a separate but similar spark gap electrode assembly.

each test shall be carried out suing a new needle and each needle shall be discarded after a miximum of 60 repetitive sparks.

每次試驗應更換新針，而且根針zui多使用了60次後就必須丟棄。

note 2. a suitable type of needle for use in the artificial fault divece is given in annex d.

注釋2：人工擊穿裝置中所使用的針的型號的規(guī)定見附錄d。

annex c (informative) 附錄c

procedure for checking the efficacy of the method of spark testing

火花試驗效果的檢定程式

c.1 principle  原則

the principle of this method is to standardize the method by which manufacturers may demonstrate that their spark testing is effective in detecting faults in the insulation as specified in clause 9.

這個方法的原則是為了證明哪個製造商所進行的絕緣火花試驗是符合第9條規(guī)定的標準的。

it is imperative that the manufacturer"s instructions for production and control procedures provide that cables for which spark testing is required are effectively tested in practice.

指導製造商，哪種火花測試試驗符合他們所生產的電線或電纜的檢測要求。

c.2 se-lection and preparation of test pieces  測試品的準備

c.2.1 sampling  取樣

prepare two test lengths of core/cable, one with the smallest insulation thickness,the other with the largest insulation thickness that the equipment will be required to test, for the relevant types of cable.

準備兩條被測電線或電纜，一條絕緣厚度比較薄，另一條絕緣厚度比較厚。

c.2.2 preparation of punctures 破壞點的準備

prepare punctures in the insulation as follows.在被測試電線的絕緣上準備小孔

a)    remove the insulation from the core for a length of about five time the nominal insulation thickness.

 從電線上移開約5個測試時間長的絕緣塊。

b)    from the piece of insulation which has been removed, remove a segment of about 30°, then replace the remaining place of the insulation on the conductor (see figure c.1).

 從已經除去的絕緣片中，在除去30°的部分，再把絕緣片放回電線的原位。

c)    over the replaced piece of the insulation,place one layer of adhering tape,e.g. polyethylene terephthalate,with a length of at least 10 times the nominal insulation thickness,in a longitudinal direction,with an overlap. situate this overlap on the opposite side of the core to the position where the insulation was removed (see figure c.2).

d)    in this layer,in the middle of the place where the insulation has been removed,use a hot needle to punch a hole in the tape with a diameter equal to half of the allowed minimum insulation thickness. prepare the other test piece in the same way.

c.3 procedure  程式

c.3.1 efficacy of detecting

pass the prepared test pieces through the spark test equipment at the highest speed for which the equipment is to be used,the voltage applied between the electrode and the conductor being that normally used.

c.3.2 recovery time  恢復時間

pass at least two faults through the spark test equipment at its actual operating speed v in metres per second,the distance in metres between two faults being not greater than the of v.

恢復時間就是能夠檢測出連續(xù)兩個破壞點所需的時間，也就是能夠檢測出的兩個連續(xù)破壞點間的zui小長度與穿過測試電極的線速的比?；謴蜁r間小於這個比值。

annex d (informative)

needle for use in the artificial fault device  人工破壞試驗裝置所用的針

the point of the needle shall be formed from a 1.0 mm steel rod over a distance of 3.75mm along the axis as illustrated in figure d.1. the radius of the point shall be less than or equal to 0.03mm. a portion of a needle widely available from commercial sources.1)