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UL 60947-7-2-2017 pdf free download
UL 60947-7-2-2017 pdf free download.Low-Voltage Switchgear and Controlgear — Part 7-2: Ancillary Equipment — Protective Conductor Terminal Blocks for Copper Conductors.
lithe connection to the support is also made screwless, five further protective conductor terminal blocks are arranged adjacently on their support (see figure 4), The test is made with heat-resistant insulated or non-insulated conductors having the rated cross-section.
The protective conductor terminal blocks are placed in a heating cabinet, which is initially kept at a temperature of (20 ± 2) °C and then submitted to the verification of the voltage drop test according to
The whole test arrangement, including the conductors, shall not be moved until all the voltage drop tests have been completed.
The protective conductor terminal blocks are submitted to 192 temperature cycles as follows.
For protective conductor terminal blocks intended for use under ‘normal service conditions” (maximum 40 CC), the temperature in the heating cabinet is increased to 85 bC.
For protective conductor terminal blocks for which the manufacturer has specified maximum service conditions above 40 °C. the temperature in the heating cabinet is increased to the temperature specified by the manufacturer plus 45 K.
The temperature is maintained within ± 5 ‘C of this value for approximately 10 mm.
The protective conductor terminal blocks are then cooled down to a temperature of approximately 30 °C, forced cooling being allowed: they are kept at this temperature for approximately 10 mm and, It necessary for measuring the voltage drop, it is allowed to cool down further to a temperature of (20 ± 5) °C.
NOTE: As a guide, a value for the heating and cooling rate of the heating cabinet of approximately 1,5 CImln may be taken as a basis.
The voltage drop in each protective conductor terminal block is also determined according to 8.4.4 after each of the 24 temperature cycles and after the 192 temperature cycles have been completed, each time at a temperature of (20 ± 5) °C.
In no case the voltage drop U at the clamping units for the copper conductors shall exceed 4.8 mV or 1,5 times the value measured after the 24m cycle, whichever is the lower.
At the clamping units to the support, the voltage drop U shall not exceed 9,6 mV or 1,5 times the value measured after the 24th cycle, whichever is the lower.
If one of the protective conductor terminal blocks does not withstand the test, the test is repeated on a second set of protective conductor terminal blocks, all of which shall then comply with the repeated test.UL 60947-7-2-2017 pdf free download.
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