IEC 60143-3:1998 pdf download – Series capacitors for power systems -Part 3: lnternal fuses

IEC 60143-3:1998 pdf download – Series capacitors for power systems -Part 3: lnternal fuses.
This part of IEC 60143 concerns Internal fuses designed to Isolate faulty capacitor elements, to allow operation of the remaining parts of that capacitor unit and the bank in which the capacitor unit is connected. Such fuses are not a substitute for a switching device such as a circuit- breaker, or for external protection of the capacitor bank, or any part thereof.
The object of this standard is
— to formulate requirements regarding performance and testing:
— to provide a guide for coordination of fuse and bank protection.
NOTE — External tusea br sen.. capacbors are treated in lEG 60143-I. annex A: 1a1 requwenenta and
application QuidC for external fuses arid units to be externally fused.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of IEC 60143. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of IEC 60143 are encouraged to investigate the possibility of applying the most recent edition of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards
fEC 60050(436): 1990, International Electrotechnical Vocabulary (1EV) — Chapter 436: Power capacitors
IEC 60143-1:1992, Series capacuors lot power systems — Part I: General — Pertormance. testing and rating — Safety requirements — Guide for installation
IEC 60143-2:1994 Series capacitors for power systems — Part 2: Protective equipment for series capacitor banks
1.3 DefinitIons
For the purpose of this part of IEC 60143. the following definitions apply.
1.3.0 Definitions of capacitor parts and accessories: these are in accordance with IEC 601 43-1 and IEC 60143•2.
NOTE — In title standard, the word e1,nwnqs Is used in accodance with tile definitions contained in IEC capacitor publications, and riot in accordanc, with the IEC fuSe piAlicatione.
1.3.1
internal fuse
fuse connected inside a capacitor unit in series with an element or group of elements
1.3.2
lImIting voltage (Utim)
ma,iimum instantaneous voltage appearing between the capacitor terminals. divided by 2. This voltage appears either during operation of the varistor or immediately before sparkover of the spark gap
1.3.3
rated voltage (of a capacitor) (U4)
r.m.s. value of the voltage between the terminals, derived from rated capacitance, rated current and rated frequency [1EV 436-01-15 modified)
1.3.4
bank protection
general term for all protective equipment for a capacitor bank, or part thereof
1.3.5
unbalance protection:
device sensitive to capacitance difference between branches of the bank normally in balance with each other. The capacitance difference may be due to a blown fuse(s), or an insulation failure within the bank
NOTE — Othe proreciie devices. such as overcurrent and cain fault protection, are sell-explanatory. since they are commonly used for other applications,
Section 2: Performance requirements
2.1 General
The fuse is connected in series with the element(s) which the fuse is intended to isolate it the element(s) becomes faulty The range of currents and voltages for the fuse is therefore dependent on the capacitor design, and in some cases also on the design of the bank in which the fuse is connected.
The operation of an internal fuse is in general determined by one or both of the two following factors:
— the discharge energy from elements or units connected In parallel with the faulty element or unit;
— the power-frequency fault current
2.2 DIsconnecting requIrements
The fuse shall enable the laulfy element to be disconnected when electrical breakdown of elements occurs in a voltage range, in which u1 is the lowest, and u2 is the highest (instantaneous) value of the voltage between the terminals of the unit at the Instant of faulL
The recommended values for u1 and u2 are the following.