The purpose of earthing/bonding PV module frames is both for protective and functional NOTE: reasons. The functional aspect of this requirement enables the PCE’s earth fault detection to detect leakage to earth and provide alarm indication. The requirement of a minimum size of 4 mm 2 applies to the frame earth connections and is for mechanical durability reasons. 220.127.116.11 Protective equipotential bonding There are two forms of protective bonding—main equipotential bonding and supplementary equipotential bonding. Main equipotential bonding is the connection of exposed conductive parts to the installation main earthing terminal. Supplementary equipotential bonding is the connection of exposed conductive parts to exposed conductive parts or to extraneous conductive parts, or both. Supplementary equipotential bonding might be required in order to keep the magnitude of the voltages between simultaneously accessible exposed conductive parts or extraneous conductive parts, or both, sufficiently low to prevent electric shock. PV array frame protective bonding shall be carried out in accordance with the decision tree presented in Figure 4.5. PV array frame used here refers to the PV module frames. NOTE: Protective equipotential bonding shall be installed so as to prevent a non-earthed situation if a component of the system is removed for any reason. All PV array protective equipotential bonding conductors shall comply with the material, type, insulation, identification, installation and connection requirements specified in AS/NZS 3000. Accessed by UNSW - LIBRARY on 06 Apr 2017 (Document currency not guaranteed when printed)
53 AS/NZS 5033:2014 COPYRIGHT 18.104.22.168 PV array protective bonding installation PV array protective bonding conductors shall be run as close to the positive and negative PV array and sub-array conductors as possible to reduce induced voltages due to lightning. 4.4.3 Functional earthing of PV arrays 22.214.171.124 General To achieve earthing of a PV array for functional reasons such as removal of surface charge from cells, two methods are allowed: Direct functional earthing so that either the positive or negative of the PV array main (a) conductor is directly connected to earth. This is required to be carried out via an earth fault interrupter (see Clauses 3.4.2 and 126.96.36.199). Functional earthing of either the positive or negative of the PV array main conductors (b) via a resistor. The rating of the resistor in the expected operating environment shall be as follows: (i) A minimum resistance of PV array maximum voltage /0.3. (ii) The resistor shall be rated for a power dissipation greater than or equal to the following: ( PV array maximum voltage ) 2 / Resistance (expressed in watts). (iii) Rated for full PV array maximum voltage. 188.8.131.52 Functional earthing terminal of PV system When the PV array is earthed for functional reasons, the connection to earth shall be made at a single point, and this point shall be connected to the earth busbars of the electrical installation switchboard.
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