IEC 62497-2 pdf download

IEC 62497-2 pdf download.Railway applications – Insulation coordination – Part 2: Overvoltages and related protection
1 Scope
This part of IEC 62497 applies to: – fixed installations (downstream the secondary of the substation transformer) and rolling stock equipment linked to the contact line of one of the systems defined in IEC 60850; – rolling stock equipment linked to a train line. This standard gives simulation and/or test requirements for protection against transient overvoltages of such equipment. Long-term overvoltages are not treated in this standard.
2 Normative references
The following referenced documents are indispensable for the application 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 60099-1 , Surge arresters – Part 1: Non-linear resistor type gapped arresters for a.c. systems IEC 60099-4, Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c. systems IEC 60850, Railway applications – Supply voltages of traction systems IEC 61 992-5, Railway applications – Fixed installations – D.C. switchgear – Part 5: Surge arresters and low-voltage limiters for specific use in d.c. systems UIC 550, Power supply installations for passenger stock
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply: 3.1 voltages 3.1.1 overvoltage any voltage having a peak value exceeding the corresponding peak value of maximum steady-state voltage at normal operating conditions 3.1.2 temporary overvoltage an overvoltage of relatively long duration due to voltage variations NOTE A temporary overvoltage is independent of the network load. It is characterized by a voltage/time curve. 3.1.3 transient overvoltage A short duration overvoltage of a few milliseconds or less due to current transfer NOTE A transient overvoltage depends on the network load. It cannot be characterised by a voltage/time curve. Basically, a transient overvoltage is the result of a current transfer from a source to the load (network). 3.1.3.1 switching overvoltage the transient overvoltage at any point of the system due to specific switching operation or fault [IEC 60664-1 , 3.7.3] 3.1.3.2 lightning overvoltage the transient overvoltage at any point of the system due to a specific lightning discharge 3.2 network set of conductors fulfilling a certain function, the overvoltages of which are likely to damage the equipment they are connected to
4 Contact line network
NOTE The provisions of this Clause 4 do not take into account rapid transient overvoltages in the multimegahertz range such as generated by operation of vacuum circuit breakers which may require a specific overvoltage protection. 4.1 Equipment not protected by a metal-oxide arrester If the equipment is not protected by a metal-oxide arrester, the protection against overvoltages shall take into account overvoltages limited only by the intrinsic isolation of the contact line and the possible presence of other types of arrester or spark gaps. 4.2 Equipment protected by a metal-oxide arrester 4.2.1 General If the supplier wants to benefit from the presence of a metal-oxide arrester for reducing constraints resulting from 4.1 , he shall perform a simulation of the behaviour of the protection against overvoltages. The circuits of the protected equipment likely to modify the electrical behaviour of the protection shall also be simulated. The equipment shall withstand the pulses defined in 4.2.2 and 4.2.3, where the values of the reference voltage U p are defined in Table 1 ..2.2 Simulation for long pulse The long pulse is a voltage pulse of trapezoidal shape, lasting 2 ms with an amplitude equal to 70 % of the reference voltage U p . It is applied to the equipment without considering the presence of its metal-oxide arrester. 4.2.3 Simulation for short pulse The short pulse is the 4/1 0 current pulse defined in IEC 60099-4. Its amplitude value is 1 00 kA. It is applied to the equipment including the arrester, where the metal-oxide arrester is replaced by a theoretical one the characteristic of which, in log(current in kA) versus log(voltage in kV), is a straight line which includes the two points: