IEC 62505-3-1:2009 pdf free download

IEC 62505-3-1:2009 pdf free download Railway applications – Fixed installations – Particular requirements for a.c. switchgear – Part 3-1: Measurement, control and protection devices for specific use in a.c. traction systems – Application guide
1 Scope
This part of lEC 62505 provides assistance，guidance and requirements in the design ofprotection，control and measuring systems in a.c. installations at traction voltages (seeiEC 60850) intended to provide a power supply to traction systems. This application guideidentifies the characteristics and parameters of equipment used in the measurement,controland protection of a.c. traction systems.Guidance is given in the correct use of protection.
2Normative references
The following referenced documents are indispensable for the application of this document.Fordated references,only the edition cited applies. For undated references, the latest edition ofthe referenced document (including any amendments) applies.
IEC 62505(all parts)，Railway applications – Fixed installations – Particular requirements fora.c. switchgear
IEC 60850，Railway applications – Supply voltages of traction systems
Measurement
Two types of measurements are made:
a) measurement of current and voltage signals for connecting to instruments and telemetering;
b) measurement of current and voltage signals used for operating protection relays on overcurrent, low impedance,overlunder-voltage and short circuit or distance protection.
The class，ratio and burden should be selected from the values in lEC 62505-3-2 orIEC 62505-3-3.The accuracy and purpose are dependant on the class selected.
4 Closing control systems
4.1General
The application of the features described below depends on the philosophy of the user’scontrol system.
Closing control systems are usually only those which involve the electrical closing of switchgeardevices.Their effect is to permit or inhibit a closure depending on the status of the system (andplant) and the compliance of specified requirements.
4.2 Anti-pumping
This system limits the closing device to effect a single attempt while the signal to close is maintained. If the device fails to complete a satisfactory close operation whilst the close signal is maintained, then attempts at further reclosing (pumping) are inhibited.
An anti-pumping can be achieved in the closing control circuit in various ways, either by using circuit-breaker mechanism auxiliary switches or a timing relay. It only allows a single closing pulse to the closing device, which resets when the initial closing signal is released.
The purchaser should specify the need for anti-pumping feature.
4.3 Auto-reclose with variable reclose time and final lock out
Auto-reclose is only applied to line circuit-breakers and its purpose is to restore the system voltage to the overhead contact line automatically when there is a temporary loss of supply.
On traction systems a temporary loss of supply is not always due to permanent short circuits and an auto-reclose system can enhance the reliability of the system.