This part of 61347 specifies particular safety requirements for electronic invertors and convertors for high-frequency operation of tubular cold-cathode discharge lamps used in signs and luminous discharge tube installations and operating with an output voltage exceeding 1000 V but not exceeding 10000 V for direct connection to supply voltages not exceeding 1000 V at 50 or 60 Hz or 1000 V d.c. The requirements for two types of invertors and convertors, types A and B, are specified as follows: Type A unit: an invertor or convertor operating within the frequency range 20 kHz to 50 kHz, and having an output voltage (between terminals) not exceeding 5000 V peak, a maximum output current limited to 35 mA (r.m.s.) and 50 mA (peak value). The supply voltage does not exceed 250 V at 50 Hz or 60 Hz or 250 V. d.c. Type B unit: an invertor or convertor having a no-load output voltage not exceeding 5000 V to earth or 10000 V between terminals, operating within the frequency range 10 kHz to 100 kHz with a maximum output current limited to 200 mA (r.m.s.) and 400 mA (peak value). In order to check the safety of invertors or convertors, it is necessary to check their performance. However, since no standardization of the characteristics of neon tubes exists, reference loads are specified in this standard to ensure reproducible test results. The rated maximum operating temperature of the winding, tw, is not applicable to this standard.