"ADVISORY NOTE RESIDUAL CURRENT DEVICES TESTING"
ADVISORY NOTE RESIDUAL CURRENT DEVICES TESTING Mines and Petroleum Division 18 August 2004 ENG 318 As the effect of electrical current through the body depends largely upon the magnitude and duration of the current flow and the path taken, any current exceeding 30mA AC is likely to lead to serious injury if not rapidly disconnected. Furthermore, the prolonged flow of a leaking current to earth through parts of an installation create a heating and galvanic effect that can damage or set the equipment or associated surrounding material on fire. Residual Current Devices (RCD’s) are set to instantaneously trip the circuit protection when a current of a magnitude of 30mA or more flows from an active to earth or earthed person or equipment. 1. REQUIREMENTS A test of the effectiveness of residual current devices is required as specified in AS/NZS 3760. The results of the test are to be recorded and the record made available to a Mining Officer on request. 2. TESTING All RCD’s must be tested by an Electrician prior to their initial introduction to service, before return to service after a repair or servicing, which could have affected the electrical safety of the device. All RCD’s must be tested by a Competent Person at intervals not exceeding those specified in Table 4 of AS/NZS 3760 or other intervals appropriate to particular industries, specific location or types of equipment. The test is to be carried out using an approved and calibrated test instrument. The test instrument must have the facility to pre-set the value of the injection current and to give an accurate read out of the time taken by the device to operate at each selected current level. For further information or advice on this subject please contact the: Mines and Petroleum Division Department of Business Industry and Resource development Phone : (08) 8999 6528 E-mail : firstname.lastname@example.org Page 1 of 5 3. RECORDS After carrying out the test the Competent Person must record the results of the test and sign on a document bearing the name of the Mine, the date of the test and the exact location and identification of the device. The original of the test record must remain on the Mine site to be examined if required by a Mining Officer. 4. DEFINITIONS (for the purpose of this test record procedure) All RCD’s protecting power outlets, includes portable RCD’s and those mounted on electricity generating sets, welding machines and other equipment. Location Building, MCC, Switchboard and circuit number. Device Rated residual current: value of nominal residual (leakage) current at which positive operation of the RCD or relay is ensured. I∆ n I∆ n Test to be carried out at half the rated residual current. 2 The device shall not trip. trip/no trip I∆ n Test to be carried out at rated residual current. T =<300 ms The device shall trip within the maximum time of: Type I RCD 40 ms. Type II and III RCD 300 ms. Type IV RCD minimum 130 ms and maximum 500 ms. 5 x I∆ n Tests to be carried out at five times the rated residual current. The device shall trip within the maximum time of: minimum t =< 40 ms Type I,II,III RCD 40 ms. Type IV RCD minimum 50 ms and maximum 150 ms. 180° Test to be carried out as above changing the polarity initiating the test at a different transition point, negative to positive or positive to negative, to ascertain the maximum time taken to trip. Comments Any comment relevant to the test or the device. Page 2 of 5 5. CLASSIFICATION OF RCD’s Type I RCD’s and relays with rated residual current not exceeding 10 mA. Type II RCD’s and relays with rated residual current in excess of 10 mA but not exceeding 30 mA. Type III RCD’s and relays with rated residual current in excess of 30 mA but not exceeding 300 mA, without selective tripping time delay characteristics. Type IV RCD’s and relays with rated residual current in excess of 30 mA but not exceeding 300 mA, with selective tripping time delay characteristics 6. REFERENCES - AS/NZS 3000 Wiring rules - AS 3190 Approval and test specification - Residual current devices - AS/NZS 3760 In-service safety inspection and testing of electrical equipment - AS 3859 The effect of current passing through the human body Page 3 of 5 EXAMPLE - RCD DEVICES TEST RECORD SHEET Mine:______________________________________________________________________ Date: ______________________________________________________________________ Tested by: __________________________________________________________________ Signature:___________________________________________________________________ Location Device I∆ n I∆ n 5 x I∆ n 180° Comments I∆ n 2 t=<300ms minimum trip/ t=<40ms no trip W/Shop DB6 Circuit No.5 30mA no trip 70ms 35ms 38ms new device Circuit No.9 30mA no trip 18ms 23ms 31ms Portable No.2 30mA no trip 14ms 16ms 23ms Gen-Set GS7 30mA no trip 54ms 29ms 32ms Welder W9 30mA no trip 36ms 22ms 28ms Plant DB2 Circuit No.4 30mA no trip 500ms 240ms fail tagged-off to be replaced fail tagged-off Circuit No.16 30mA trip to be replaced Page 4 of 5 RCD DEVICES TEST RECORD SHEET Mine: Date: Tested by: Signature: Location Device I∆ n I∆ n 5 x I∆ n 180° Comments I∆ n 2 t=<300ms minimum trip/ t=<40ms no trip Page 5 of 5