IEEE 1627:2019 pdf free download – IEEE Standard for Transient Overvoltage Protection of DC Electrification Systemsby Application of DC Surge Arresters
1.1 Scope
This standard covers the application of dc surge arresters for transient overvoltage protection of dc transitelectrification systems. These dc transit electrification systems include light rail, heavy rail, streetcar, andtrolley bus systems. This standard covers the selection and application of metal-oxide varistor (MOV) gapless-surge arresters to divert surge energy away from the transit system components. It does not cover low-voltageSPDs that are required within dc traction power system equipment, such as rectifier units, vehicle propulsionsystems, or other sensitive components of the dc transit system.
1.2 Purpose
lt is the purpose of this standard to provide uniform practices for lightning and switching transient overvoltageprotection of de transit electrification by proper selection of dc surge arresters based on the surge environmentand site conditions of the transit system. This standard allows the use of SPDs in dc transit systems to avoidinsulation failure due to transient overvoltage. Transient overvoltage protection is just as important as short-circuit protection.This standard will minimize equipment damage caused by transient overvoltages, increasingsystem reliability that will result in reduced maintenance.
1.3 Contents
First,the basic charactcristics of transient surges，their origin，and energy and propagation behaviorare described in Clause 4 and Clause 7.This is followed by a brief description of the surge environmentexpected at dc electrification system in Clause 5 and Clause 7.Clause 5 also includes dc SPD requirements forcomparison of transient overvoltage protection, dc surge arrester tested parameters by manufacturers, surgearrester application analysis calculation, and energy absorbing (handling) capability.Clause 6 and Clause 7cover analysis of lightning strikes to the dc transit clectrification system components. Clause 8 covers surgearrester grounding and grounding of OCS poles. Clause 9 includes dc surge arrester application locationsand discussion of application parameters including various voltages assigned to a dc surge arrester to help inthe selection of dc surge arresters. In addition, Clause 9 includes insulation and BIL levels of dc switchgear.Clause 10 covers dc surge arrester service requirements. Clause 1l covers dc surge arrester assembly andtesting and design and field tests, including an application example of dc surge arresters to OCSs.
4. Transient surges
Transient surges are caused by lightning, switching phenomena within the system, or induced and impressedvoltages that become superimposed over the dc power system voltage. They are unpredictable and knownto be brief. Their wave-shape, magnitude, and energy content may vary considerably, depending upon theircause of origin, the system configuration, and surge-impedance parameters. This is the design intent thatsuch transient overvoltages and associated energy shall be diverted away from the dc power system by theapplication of appropriate dc surge arresters at specific locations within the overall electrification system.Lightning surges (called extermal surges) can strike on the dc electrification system directly or indirectly andcan induce transient overvoltages with considerable energy to create hazards.Switching surges (called internalsurges) are caused by sudden changes in the dc electrification system, such as dc breaker operation, opening ofa fuse, sudden load drop, de regeneration, etc. Typically, they are not as severe as lightning surges due to theirrelatively low energy contents.