Detail of GB/T 18216.7-2024

Introduction of GB/T 18216.7-2024

GB/T 18216.7-2024 Electrical safety in low voltage distribution systems up to 1000 V a.c. and 1500 V d.c. - Equipment for testing, measuring or monitoring of protective meas-ures - Part 7: Phase sequence 1 Scope This document specifies the requirements applicable to measuring equipment for testing the phase sequence in three-phase distribution systems. Indication of the phase sequence can be mechanical, visual and/or audible. This document does not apply to additional measurements for other quantities. It does not apply to monitoring relays. Note: Common worldwide three-phase distribution systems are depicted in IEC 61010-1:2016. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 18216.1-2021 Electrical safety in low voltage distribution systems up to 1000 V a.c. and 1500 V d.c. - Equipment for testing,measuring or monitoring of protective measures - Part 1: General requirements IEC 61010-1:2010 Safety requirements for electrical equipment for measurement, control, and laboratory use - Part 1: General requirements IEC 61010-2-030 Safety requirements for electrical equipment for measurement, control, and laboratory use - Part 2-030: Particular requirements for equipment having testing or measuring circuits IEC 61010-031 Safety requirements for electrical equipment for measurement, control and laboratory use - Part 031: Safety requirements for hand-held and hand-manipulated assemblies for electrical test and measurement 3 Terms and definitions For the purposes of this document, the terms and definitions given in GB/T 18216.1-2021 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: ——IEC Electropedia: available at http://www.electropedia.org/ ——ISO Online browsing platform: available at http://www.iso.org/obp 3.1 phase sequence indicator instrument intended to indicate, in a polyphase system, the sequence in which the instantaneous voltages of the phase conductors reach their maximum values [SOURCE: GB/T 2900.79-2008, 313-01-21] 3.2 phase sequence indication information displayed by a phase sequence indicator 3.3 phase sequence test test taken to determine that the phase sequence of a polyphase winding is correct [SOURCE: GB/T 2900.25-2008, 411-53-45] 4 Requirements 4.1 General In addition to the requirements of GB/T 18216.1-2021, Clause 4, the requirements of Clause 4 of this document shall apply. 4.2 Indication All indications shall be unambiguously displayed on the phase sequence indicator when the input to the phase indicator is between 85 % and 110 % of the nominal system voltage and between 95 % and 105 % of the nominal system frequency. Indications shall also be unambiguously detectable in the presence of visual or audible interference. The phase sequence indicator shall display a valid phase sequence indication, positive or negative, if the values of the voltage to earth of the three phases are within the voltage range specified above and the phase delay between two consecutive phases is 120°. The phase sequence indicator shall not display a valid phase sequence indication, positive or negative, if the three-phase distribution system is heavily unbalanced. Note: An unbalanced system could be due to unbalanced loads on the three phases or due to cabling errors. In particular the measuring equipment shall not display a valid phase sequence indication in the following cases: a) one or more of the phase conductors are open-circuit; b) one or more of the phase conductors are connected to neutral or protective earth; c) two conductors are connected to the same phase. The specific indications displayed in the above error cases shall be mentioned in the operating instructions of the phase sequence indicator. The limits of unbalance in amplitude and in phase delay that the phase sequence indicator can handle reliably shall also be mentioned in the operating instructions. 4.3 Measuring equipment 4.3.1 General The measuring equipment for the phase sequence test is intended for temporary operation, but shall withstand continuous operation. Equipment intended to be used on the distribution system shall be rated at least for measurement category III according to IEC 61010-2-030. Equipment intended to be used on socket outlets only can be rated for measurement category II according to IEC 61010-2-030. The measuring equipment shall not be damaged nor shall the user be exposed to danger when the measuring equipment is connected to 120 % of the rated system voltage or to 120 % of the maximum voltage of its rated voltage range. The phase sequence test (see Annex B) can be realised with test probes for direct contact with live parts, conductors or terminals, or with test clamps for inductive detection on insulated conductors. 4.3.2 Portable phase sequence indicator Portable phase sequence indicators shall be housed in an enclosure of insulating material and comply with the requirements for double insulation or reinforced insulation (protection class II). Portable phase sequence indicators shall be designed in such a manner that when either one or two measuring leads are connected to earth and the remaining measuring leads are connected to their corresponding phase conductors, the resulting total current to earth should not exceed 3.5 mA RMS. The phase conductors shall be at 110 % of the maximum rated voltage for which the equipment is designed. 4.3.3 Test leads for direct contact with live parts and accessories Phase sequence indicators designed for direct contact to live parts shall be provided with permanently connected test leads or with terminals for removable test leads complying with IEC 61010-031. The following applies to leads. Test probes, test leads, clips and other accessories used with phase sequence indicators shall be in accordance with the requirements of IEC 61010-031. A test lead cable that has a wear indicator shall, at the minimum, provide double insulation or reinforced insulation when new and, at the minimum, basic insulation when the wear indicator is reached (see IEC 61010-031). Portable measuring equipment, together with its test leads, shall comply with the requirements for mechanical strength according to IEC 61010-1:2016 and in addition shall be tested in accordance with 6.3.1. These requirements do not apply when the phase sequence indicator forms part of a multi-purpose instrument with provisions for carrying.

Contents of GB/T 18216.7-2024