EN 61235-1995 pdf download.Live working Insulating hollow tubes for electrical purposes.
individuals using, maintaining or depending upon the product; or a defect that judgment and experience indicate is likely to prevent performance of the function of a major end item (see 2.1.1)
3.3 Definitions of special terms
3.3.1
reinforced tube
tube which is especially designed in order to resist important mechanical strain, usually made of specific materials such as fibreglass
(see Table 4, Table 7 and Table 9)
3.3.2
standard tube
tube which may he submitted occasionafly to mechanical loading and should he able to self-restore by the nature of the material itself
(see Table 5, Table 7 and Table 9)
3.3.3
light tube
tube which has not been designed and manufactured to resist mechanical stresses except its own weight (see Table 6 and Table 8)
4 Classification
4.1 Mechanical category
Hollow tubes are classified in three categories according to their mechanical characteristics.
These categories are: reinforced tube, standard tube and light tube.
in all three cases, the tubes shall comply with dielectric tests specified in this standard.
4.2 Electrical category
There is only one electrical category.
The electrical properties shall be the same for the three mechanical categories.
NOTE Hollow tubes should be used in areas having ambient temperature between —40 °C and + 70 °C.
9 Dielectric tests
These tests are carried out to verify the ability of the products to withstand:
— dielectric stress before exposure to humidity (see 9.1.2);
— dielectric stress after exposure to humidity (see 9.1.3)
9.1 Dielectric tests before and after exposure to humidity
9.1.1 General test conditions
Before dielectric testing, each test piece shall be prepared by cleaning outside and inside with isopropanol (CH3—CH(OH)—CH3) and then dried in air for 15 mm.
NOTK It is the duty of an employer to ensure that the relevant legislation and safety requirements for the use of this chemical are complied with in their entirety.
These tests are made on three test pieces, each 300 mm long, which are cut from tubes of hatch no. I in such a way as to avoid the use of material within 100 mm of the end.
The ends of these test pieces shall then be covered with conducting adhesive tape before each dielectric test. At the time of conditioning in a humid atmosphere, this conducting adhesive tape shall be removed.
Conditioning in a humid atmosphere shall be carried out in accordance with IEC 212.
The test location shall beat the standard atmospheric conditions of Table 1, IEC 212, with a temperature range of 18 °C to 28 °C.
The test arrangement is shown in Figure A.1 (Annex A). The measuring equipment shall be at least 2 m from the HV electrode. The measuring leads, shunt and optional protective gap shall be shielded and earthed.
The test piece shall be mounted on an insulating support approximately 1 m above the ground plane. An alternating voltage at power frequency is applied between the electrodes, and the current passing through the test piece is measured (the guard electrode on the earth side is connected direct to earth).
The specified currents are given in r.m.s. values. The phase difference between current and voltage is measured as follows:
— current (earth end), by passing it through a known impedance (see Figure A.1, Annex A);
— voltage (line end), by means of an appropriate divider.
During the tests there shall be no sign of flashover or puncture of any of the test pieces.
9.1.2 Tests before exposure to humidity
After at least 24 h in the ambient atmosphere of the test area, a voltage of 50 kV r.m.s. at power frequency is applied for I mm between the electrodes and the current I is measured.
The maximum current I is recorded.
Then after I has been recorded, the voltage shall be increased until 100 kV r.m.s. and maintained for 1 mm.
The test piece shall fulfil the following requirements:
no flashover, no sparkover or puncture;
— no visual sign of tracking or erosion on the surface;
— no perceptible temperature rise (5 °C).
NOTE The test method of temperature measurement is under consideration.
9.1.3 Tests after exposure to humidity
The test pieces are placed in a chamber and subjected to the following conditioning:
168 h123 °C193 O/, according to Table 1 of IEC 212.
At the end of this 168 h period, the test pieces shall remain in an atmosphere of 93 % relative humidity and be tested upon return to the ambient temperature of the test area. After the test pieces have been lightly wiped inside and outside with a dry, lint-free cloth a voltage of 50 kV r.m.s. at power frequency is applied for I mm, between the electrodes.EN 61235-1995 pdf download.