This part of IEC 61243 is applicable to voltage detecting systems that are single-pole and are capacitively-coupled to live parts. They are used to detect the presence or absence of operating voltage on a.c. electrical systems for voltages from 1 kV to 52 kV, and for frequencies from 162/3 Hz to 60 Hz. This standard is also applicable to phase comparators designed for voltage detecting systems. EMC tests are not included as, at the present time, not enough information about minimum requirements is available. NOTES 1 Except where specified otherwise, all the voltages defined in this standard refer to values of phase-to-phase voltages of three-phase systems. In other systems, the applicable phase-to-phase or phase-to-earth voltages are used to determine the operating voltage. 2 Voltage detecting systems based on fundamentally different principles (for example optical systems, resistive coupling elements) are not covered in this standard but should meet the requirements of this standard where applicable. 3 For frequencies differing from 50 Hz, the values Cs and Ut according to table 1 are valid. The threshold values for It have to be changed accordingly. 4 If in an electrical installation it is verified that the installation is dead by other means than using a voltage detecting system, a different device which can be termed voltage indicating system may be used for service information about the voltage state with reduced requirements concerning tests for clear and reliable indication. If so, this should be clearly stated and made explicit by the manufacturer (see annex F for further details).