IEC 60947-5-8:2020 pdf free download – Low-voltage switchgear and controlgear
9.3.3.6.2Mechanical durability
The three samples (see 9.1) shall be subjected to the following test.
The test shall be performed for minimum 50 000 cycles of position 1 → 2→ 1 operation andminimum 50 000 cycles of position 1 → 2→ 3 → 1 operation.The actuator of a three-positionenabling switch shall be subjected to the forces necessary to achieve the required positions.
The maximum rated operating force specified by the manufacturer (see F5 as defined inFigure 2) is applied at position 3.
The movement and actuating forces of the three-position enabling switch shall be consistentthroughout the test.This shall be verified by measurement before and after the tests.
The mechanical durability of the three-position enabling switch is defined as the number ofno-load operating cycles which will be attained by all samples tested without repair orreplacement of any part.
Tests shall be carried out according to C.1.2 of lEC 60947-5-1:2016.
During the test,the enabling contacts shall be checked at each change of state by themanufacturer at the conditions described below,and there shall be no failure.
Test voltage and current: 24 v DC,10 mA maximum.
Test method: The agreement of switch position and enabling contact status shall be checkedat every position before shifting to the next position.
The enabling contact status shall be checked at each position. The three-position enablingswitch shall be shifted to the next position only when the agreement of switch position andcontact status has been confirmed. When any disagreement of position and contact status isfound, tests shall be stopped.
Failure criteria:
During the tests，there shall be no electrical and/or mechanical failures.Following the tests,the switching element shall pass the dielectric test of 8.3.3.4 of IEC 60947-5-1:2016 with atest voltage equal to 2 u。with a minimum of 1 0oo v.
9.3.3.6.3Electrical durability
The test conditions are those of 9.3.3.6.2 except that the circuit of the switch is energizedaccording to the manufacturer’s specified ratings in accordance with 6.1, item g).
9.3.3.7 Robustness
The actuator shall withstand a force of 150 % of the maximum rated operating force specifiedby the manufacturer (see F5 as defined in Figure 2), applied three times in the direction ofnormal operation in a manner simulating human action.
9.3.4 Performance under conditional short-circuit currentSubclause 8.3.4 of lEC 60947-5-1:2016 applies.
9.3.5Shock and vibration tests
9.3.5.1 Conditioning procedures
The purpose of the following procedures is to expose the three-position enabling switches tovarious environmental conditions in order to verify their functioning after such exposure.
The three three-position enabling switches shall be subjected to the following exposures:- 96 h at +40 C in dry atmosphere according to test Bb of lEC 60068-2-2;
-96 h at +5°Caccording to test Ab of lEC 60068-2-1.
Following the environmental exposures and after the samples have been restored to roomtemperature, the sequence of tests in 9.3.5.2 and 9.3.5.3 shall be conducted.
9.3.5.2Shock
The three three-position enabling switches that have been conditioned in accordance with9.3.5.1 shall be tested in each of the three mutually perpendicular axes.
Each three-position enabling switch is tested in position 1 and shall withstand 15 g shock inboth directions of each axis according to lEC 60068-2-27:11 ms – 15 g.
During the test, no closed contacts shall open and no open contacts shall close.
The monitoring means shall be able to detect any opening or closing of contacts longer than0,2 ms.