IEC 61557-7:2019 pdf download

IEC 61557-7:2019 pdf download.Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c.
1 Scope
This part of IEC 61 557 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 61 01 0-1 .
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. IEC 61 01 0-1 :201 0, Safety requirements for electrical equipment for measurement, control, and laboratory use – Part 1: General requirements IEC 61 01 0-1 :201 0/AMD1 :201 6 1 IEC 61 01 0-2-030:201 7, Safety requirements for electrical equipment for measurement, control, and laboratory use – Part 2-030: Particular requirements for equipment having testing or measuring circuits IEC 61 01 0-031 , 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 IEC 61 557-1 :201 9 Electrical safety in low voltage distribution systems up to 1 000 V AC and 1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61 557-1 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: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: IEC 60050-31 3:2001 , 31 3-01 -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: IEC 60050-41 1 :1 996, 41 1 -53-45]
4 Requirements
4.1 General In addition to the requirements of IEC 61 557-1 :201 9, 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 1 1 0 % of the nominal system voltage and between 95 % and 1 05 % 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 1 20°. 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: 1 ) one or more of the phase conductors are open-circuit; 2) one or more of the phase conductors are connected to neutral or protective earth; 3) 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.