BS 7856:2017 – TC:2020 Edition
$217.84
Tracked Changes. Specification for special design and other features of alternating current watthour meters for active energy for use in the UK (Accuracy Classes A and B)
| Published By | Publication Date | Number of Pages |
| BSI | 2020 | 78 |
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 48 | Foreword |
| 51 | 1 Scope 2 Normative references 3 Terms and definitions |
| 52 | 4 Mechanical features |
| 53 | Table 1 — Dimensions and spacing of fixing holes and terminals |
| 54 | Figure 1 — Spacing of fixing holes and terminals for single-phase, two-wire meter |
| 55 | 5 Electrical features Table 2 — Standard currents for meters of Class A or Class B |
| 57 | Figure 2 — Diagrams of connections for a single-phase, two-wire, one-rate meter |
| 58 | Figure 3 — Diagrams of connections and graphical symbols for a two-element meter used on three-wire systems |
| 59 | Figure 4 — Diagrams of connections and graphical symbols for a two-element meter used on a two-phase, four-wire system |
| 60 | Figure 5 — Diagrams of connections and graphical symbols for a three-element meter used on a three-phase, four-wire system |
| 61 | 6 Other features |
| 62 | Annex A (normative) Test method of a terminal’s ability to safely clamp standard UK cables |
| 63 | Figure A.1 — Test arrangement for clamping ability of a meter terminal |
| 64 | Annex B (normative) External rate switching logic for multi-rate meters Table B.1 — Sequence for multi-rate registers having two to eight rates |
| 65 | Annex C (normative) Long-term overcurrent test requirements |
| 66 | Annex D (normative) Performance criteria for load switches inside meters Table D.1 — Performance criteria for supply control and load control switches |
| 67 | Figure D.1 — Polyphase meter supply control switch test timing |
| 68 | Figure D.2 — Contact resistance derived from mV drop measured at meter terminals at Imax |
| 69 | Annex E (normative) Sealing criteria |
| 70 | Annex F (informative) Operational considerations related to switches inside meters |
| 71 | Figure F.1 — Typical heating in a 100 AImax meter when subjected to 1.45 * Imax |
| 72 | Table F.1 — Thermal stresses on a 100 A SCS protected by various OCPD ratings |
| 73 | Table F.2 — Characteristics of OCPDs in common domestic use in the UK |
| 74 | Figure F.2 — Current levels for determining OCPD characteristics |
| 76 | Bibliography |
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BS 7856:2017
Specification for special design and other features of alternating current watthour meters for active energy…
