20mm Brass Button Operation Tester Plug Pins Insulating Sleeves Abnormal Heat Resistance

Standard description

28.1.2 The specimen of a plug with pins provided with insulating sleeves is tested by means of the test apparatus as shown in figure 40.

This test apparatus consists of an insulating plate A and of a metal part B: between these two parts an air space of 3 mm shall be provided and this distance shall be obtained through means which do not impair the air circulation around the pins.

The front surface of the insulating plate A shall be round and flat and have a diameter equal to twice the maximum permissible dimension of the engagement face of the plug given in the

relevant standard sheet.

The thickness of this insulating plate shall be 5 mm.

The metal part B shall be of brass and have, for a distance of at least 20 mm, the same shape as the maximum outline of the plug according to the relevant standard sheet.

The rest of this metal part shall be so shaped that the accessory under test is heated through it by conduction, and the heat transmission to the accessory under test by convection or radiation is reduced to a minimum.

A thermocouple shall be inserted at a distance of 7 mm from the front surface of the metal part in a symmetrical position, as shown in figure 40.

The dimensions of the holes for the pins in the metal part B shall be 0,1 mm larger than the maximum dimensions of the pins given in the relevant standard sheet and the distances between the pins shall be the same as those given in the relevant standard sheet; the depth of the holes shall be sufficient.

NOTE 1 The metal part B can be made of two or more component pieces, for hole cleaning purposes.

The specimens are inserted in the test apparatus, placed in the most unfavourable horizontal position, when the test apparatus has reached a steady temperature, measured by means of the thermocouple, of (120 ± 5) °C for accessories having a rated current of 2,5 A, and (180 ± 5) °C for accessories having a higher current rating.

The temperature is maintained at the relevant values for 3 h.

The specimens are then taken out from the test apparatus and are allowed to cool down to room temperature, at which they are maintained for at least 4 h.

The insulating sleeves of the pins of the specimens are then submitted to an impact test in accordance with clause 30 but made at ambient temperature, and subject to visual inspection.

NOTE 2 During visual inspection, no cracks on the insulating sleeves should be visible with normal or corrected vision without additional magnification, and the dimensions of the insulating sleeves should not have changed so as to impair protection against accidental contact.