10.3.1 Purpose
To determine whether or not the module is sufficiently well insulated between current carrying parts and the frame or the outside world.
10.3.2 Apparatus

• a) A d.c. voltage source, with current limitation, capable of applying 500 V or 1 000 V plus twice the maximum system voltage of the module (as marked on the module – see Clause4) according to item c) of 10.3.4.

• b) An instrument to measure the insulation resistance.

10.3.3 Test conditions
The test shall be made on modules at ambient temperature of the surrounding atmosphere (see IEC 60068-1) and in a relative humidity not exceeding 75 %.

10.3.4 Procedure

• a) Connect the shorted output terminals of the module to the positive terminal of a d.c. insulation tester with a current limitation.

• b) Connect the exposed metal parts of the module to the negative terminal of the tester. If the module has no frame or if the frame is a poor electrical conductor, wrap a conductive foil around the edges and over the back of the module. If the module does not have a glass superstrate, also wrap the foil around the front of the module. Connect the foil to thenegative terminal of the tester.

• c) Increase the voltage applied by the tester at a rate not exceeding 500 V⋅s–1 to amaximum equal to 1 000 V plus twice the maximum system voltage (i.e. the maximumsystem voltage marked on the module by the manufacturer, see Clause 4). If the maximum system voltage does not exceed 50 V, the applied voltage shall be 500 V.Maintain the voltage at this level for 1 min.

• d) Reduce the applied voltage to zero and short-circuit the terminals of the test equipment to discharge the voltage build-up in the module.

• e) Remove the short circuit.

• f) Increase the voltage applied by the test equipment at a rate not to exceed 500 V⋅s–1 to 500 V or the maximum system voltage for the module, whichever is greater. Maintain the voltage at this level for 2 min. Then determine the insulation resistance.

• g) Reduce the applied voltage to zero and short-circuit the terminals of the test equipment to discharge the voltage build-up in the module.

• h) Remove the short circuit and disconnect the test equipment from the module.

10.3.5 Test requirements

• no dielectric breakdown or surface tracking during step c);

• for modules with total area less than 0,1 m2, the insulation resistance shall not be less than 400 MΩ;

• for modules with total area larger than 0,1 m2 the measured insulation resistance times the area of the module shall not be less than 40 MΩ⋅m2.