Skystream Owner’s Manual
3-CMLT-1054 Rev O XCO 1191
Pg. 47
Introduction
The Skystream 3.7 turbine is designed to withstand over voltages and surge currents (6kV, 3kA,
8/20
μs) caused by indirect lightning strikes or switching operations according to the Standard for
Interconnecting Distributed Resources with Electric Power Systems (IEEE 1547). For this protection to
be effective, it is necessary to ensure that over voltages at the connection terminals will not be higher
than the above values of the surge test.
To provide this over voltage protection against direct lightning strikes; a Type 1 lightning current
arrestor, that reduces over voltages to a level below 6 kV but is capable of discharging very high
currents, much larger than those handled by surge protective devices present inside Skystream is
required. Type 1 lightning arrestors have been tested to withstand over voltages and surge currents
representing a direct lightning
strike, described by a 10/350 μs type waveform.
Since the Skystream is intended to be installed worldwide in all kinds of environments, some more
vulnerable to lightning than others, the Lightning Protection
System’s (LPS) efficiency (E), and hence
the current rating of the Type 1 Lightning Current Arrestor, may be selected to meet local requirements.
Location of the Lightning Current Arrestor(s)
For Skystream installations with metallic tubular towers where the tower and turbine installation,
earthing or grounding has been performed as per
the Owner’s manual, analysis has shown that the
best protection is provided when the Type 1 arrestor is placed at or near the base of the tower.
Selecting the Appropriate Lightning Protection System
An appropriate Lightning Protection System is selected after determining the Lightning Protection
System Efficiency and thus the Lightning Protection Level (Level 1 through 4). To determine these, one
needs to further determine the following parameters.
The parameters include:
• The tower height
• Flash Density (Ng)
• Topography of Installation site
• Permitted Annual Number of Critical Events (Nc)
Once these parameters are defined a specific Model of Lightning Current Arrestor may be determined.
IMPORTANT:
More than one arrestor may be required depending upon the level of protection
required.
The Lightning Protection System (LPS) “Protection Level” is based on the number of lightning “critical
events” allowed per year and the lightning flash density in the target area. A “critical event” is described
as the failure of the lightning protection system (LPS).
If there is risk of damage to the wind turbine or associated power networks and devices due to a critical
event (or injury or loss of life), then the protection system must be designed to keep the Permitted
Annual Number of Critical Events, Nc, under an acceptable value. This is the acceptable number of
annual lightning strikes that will cause one damage incident.
IMPORTANT:
Nc is generally set by the local jurisdiction or by the owner or installer of the
system and needs to meet local safety laws.
Содержание Skystream 3.7
Страница 37: ...Skystream Owner s Manual 3 CMLT 1054 Rev O XCO 1191 Pg 37 SKYSTREAM 3 7 Appendix B Tower Grounding...
Страница 44: ...Skystream Owner s Manual 3 CMLT 1054 Rev O XCO 1191 Pg 44 Figure 4 Concrete Encased Electrode...
Страница 45: ...Skystream Owner s Manual 3 CMLT 1054 Rev O XCO 1191 Pg 45 SKYSTREAM 3 7 Appendix C LIGHTNING PROTECTION...
Страница 53: ...Skystream Owner s Manual 3 CMLT 1054 Rev O XCO 1191 Pg 53 SKYSTREAM 3 7 Appendix D CERTIFICATION COMPLIANCE...
Страница 55: ...Skystream Owner s Manual 3 CMLT 1054 Rev O XCO 1191 Pg 55 2 CE Declaration of Conformity Europe...
