AS/NZS IEC 60331.2:2017 pdf download – Tests for electric cables under fire conditions- Circuit integrity Part 2: Test method for fire with shock at a temperature of at least 830°C for cables of rated voltage up to and including 0.6/1.0 kV and with an overall diameter not exceeding 20 mm.
5.5 Positioning of source of heat
The burner face shall be positioned in the test chamber so that it is at least 200 mm above the
floor of the chamber, or any solid mounting block, and at least 500 mm from any chamber wall. By reference to the centre point of the cable to be tested, the burner shall be positioned centrally at a horizontal distance of (40 ± 2) mm from the burner face to the test wall and at a vertical distance of (V ± 2) mm from the burner horizontal central plane to the central horizontal plane of the test specimen, as shown in Figure 3 and Figure A.1.
The exact burner location to be used during cable testing shall be determined using the verification procedure given in Annex A, where the value of V to be used shall be determined.
NOTE The burner should be rigidly fixed to the framework during testing so as to prevent movement relative to the test sample.
5.6 Continuity checking arrangements
During the test, a current for continuity checking shall be passed through all conductors of the test specimen. This shall be provided by a three-phase star connected or single-phase transformer(s) of sufficient capacity to maintain the test voltage up to the maximum leakage current allowable.
NOTE 1 Due note should be taken of the fuse characteristics when determining the power rating of the transformer.
This current shall be achieved by connecting, at the other end of the test specimen, a suitable load and an indicating device (e.g. lamp) to each conductor, or group of conductors.
NOTE 2 A current of 0.25 A at the test voltage, through each conductor or group of conductors, has been found to be suitable.
5.7 Fuses
Fuses used in the test procedure in Clause 7 shall be of type DII, complying with IEC 60269-3. Alternatively, a circuit-breaker with equivalent characteristics may be used.
Where a circuit-breaker is used, its equivalent characteristics shall be demonstrated by reference to the characteristic curve shown in IEC 60269-3.
The test method using fuses shall be the reference method in the case of dispute.
6 Test specimen
6.1 Test specimen preparation
A cable sample at least 4,5m long shall be available from the cable length for test. Each individual test specimen to be tested shall be a piece of cable, taken from the cable sample. not less than 1 200 mm long with approximately 100 mm of sheath or outer coverings removed at each end.
At each end of the test specimen each conductor shall be suitably prepared for electrical connections, and the exposed conductors shall be spread apart to avoid contact with each other.
For single-, twin- or three-phase conductor cables, connect each phase conductor to a separate phase of the transformer(s) output with a 2 A fuse or circuit-breaker with equivalent characteristics in each phase. F or multicore cables that have four or more conductors (excluding any neutral or protective conductors), the conductors shall be divided into three roughly equal groups, ensuring that adjacent conductors are, as far as possible, in different groups. F or multipair cables, the conductors shall be divided into two equal groups, ensuring that the ‘ a-core of each pair is connected to one phase and the b-core of each pair is connected to another phase (L1 andL2 in Figure 8). Quads shall be treated as two pairs. For multi-triple cables, the conductors shall be divided into three equal groups, ensuring that the a-core of each triple is connected to one phase, the b-core of each triple to another phase and the c-core of each triple to the third phase of the transformer (L1, L2 andL3 in Figure 8.). Connect the conductors of each group in series and connect each group to a separate phase of the transformer output with a 2 A fuse or circuit-breaker with equivalent characteristics in each phase. NOTE 1 The above test procedure connects the neutrall conductor to earth. This may not be appropriate If the I cable Is designed for use on a system where neutral Is not earthed. If required by the cable standard it is permissible for the neutral conductor to be tested as if it were a phase conductor. Where a metalic sheath, armour or screen acts as a neutral conductor it shall always be connected to earth. Any such variations in methodology should be included in the test report. NOTE2 For cable constructions not specically identified above. the test voltage should be applied, as far as is I practicable, to ensure that adjacent conductors are connected to different phases.