WIND INDUSTRY STANDARDS
There are many wind industry codes in place to ensure the proper installation and safe operation of Wind Turbines:
UL Subject 6141 –
Large Wind Turbine Systems.
These requirements cover large wind
turbine systems (WT) and electrical subassemblies. With respect to this
standard, large WT are wind turbines where a user or service person may, or is
intended to, enter the turbine to operate it or perform maintenance. These WT
are for use in utility-interactive, grid-tied applications that operate in
parallel with an electric power system (EPS) to supply power to common or
stand-alone loads. This standard includes requirements for WT intended for EPS
grid connections at transmission, sub-transmission and distribution levels,
depending on the specifications of the specific WT.
UL Subject 6142 –
Wind Turbine Generating Systems, Small.
These requirements cover small wind
turbine systems (WT) and electrical subassemblies. With respect to this standard,
small WT are wind turbines where a user or service person is not intended or
required to enter the turbine to operate or to perform maintenance. These units
are for use in stand-alone (not grid-connected) or utility-interactive applications.
Utility-interactive, grid-tied WT are operated in parallel with an electric
power system (EPS) to supply power to common loads.
UL Subject 2277 –
Outline of Investigation for Flexible Motor Supply Cable and Wind Turbine Tray
Cable.
This outline covers the requirements
for Wind Turbine Tray Cable (WTTC) rated 1000 volts, 90 to 200°C dry and
optionally rated 90°C wet. It also covers the requirements for Flexible Motor
Supply Cable rated 1000 or 2000 volts and 90°C dry.
UL 1004–1 - Standard
for Rotating Electrical Machines – General Requirements.
This Standard applies to rotating electrical
machines and linear motors both ac and dc, rated 7,200 volts or less and is
used to evaluate both motors intended for field and factory installation. The
requirements of this Standard that address the risk of fire do not apply to a
motor provided with a metal enclosure where there are no openings in the
enclosure through which molten metal, burning insulation, flaming particles or
other ignited material could fall onto flammable material, or through which a
flame could be projected.
UL 1004–4 – Standard
for Electric Generators.
This Standard is intended to be read
together with the general requirements of UL 1004–1. The requirements in this Standard
supplement or amend the requirements in UL 1004–1. The requirements of UL
1004–1 apply unless modified by this Standard. This Standard covers electric generators,
that, when coupled with prime movers, such as engines or electric motors, are
used to produce electricity. Both generators (dc machines) and alternators (ac
machines) rated 7,200 volts or less, are covered.
CSA C61400–1–08 -
Wind Turbines - Part 1: Design Requirements.
This part of IEC 61400 specifies
essential design requirements to ensure the engineering integrity of wind
turbines. Its purpose is to provide an appropriate level of protection against
damage from all hazards during the planned lifetime. This standard is concerned
with all subsystems of wind turbines such as control and protection mechanisms,
internal electrical systems, mechanical systems and support structures. This
standard applies to wind turbines of all sizes. For small wind turbines, IEC 61400–2
may be applied.
RECENT INDUSTRY CODES CHANGES IN NORTH AMERICA
As the use of wind turbines in
industry and commercial applications becomes more prevalent, there is a growing
need to ensure their proper installation and safe operation, which has prompted
mandates to provide clearly written safety standards. While utility companies
are monitored by government agencies, non-utility applications are guided by
the National Electrical Code (NEC). In 2011, a new section called Article 694
was added to the NEC to ensure installation safety of small wind electric
systems. NEC Article 694 covers small wind power single turbines that are rated
for 100 Kilowatts (0.1KW). There is no limit to the number of wind turbines
that can be installed in a given location. When several of these machines
populate the same location, it is referred to as a “wind turbine farm” which can
cover an area of several hundred square miles.
To establish consistency and to
prevent confusion, UL has drafted several subjects corresponding to wind
turbine generating systems: UL Subject 6141: Large Wind Turbine Systems (WT)
and Electrical Subassemblies, and UL Subject 6142: Small Wind Turbine Systems
(WT) and Electrical Subassemblies. Wind turbines with entrance access are defined
as “large” per UL 6141. They are grid-connected and are used for “utility”
applications. Wind turbines without entrance access are defined as “small” per
UL 6142. They are not connected to the grid and are considered “non-utility.”
As the industry grows and the emphasis towards revision of standards continues,
UL 6141 and 6142 will be upgraded to include new requirements.
In addition, there are corresponding
UL Standards that focus on specific internal components within the wind
turbine. For example, Rotating Electrical Machines must meet UL Standard 1004–1.
Electric Generators have to meet UL Standard 1004–4, and so forth. In UL
Standard 1004–1 AWM, cables are permitted, but only with exceptions. Section
20.2 allows the use of either standard building wire or appliance wiring
material (AWM). Section 20.4 permits AWM, provided it has an insulation thickness
appropriate for the insulation material type and meets stringent cable
construction requirements. As UL Standard 1004–1 allows for the AWM option,
building wire is a “listed” product, automatically qualifying it as an NEC
compliant wiring method. It’s worth noting, however, that AWM is not an NEC
acceptable wiring method, so it may be
subject to potential acceptance issues during an inspection.
Within the construction of the wind
turbine, cable trays or raceways route and support cables to accommodate power for the various operating systems. To
address safety concerns about performance of these cables under operating
conditions inside the wind turbine, UL released an outline of investigation for
“Flexible Motor Supply Cable and Wind Turbine Tray Cable.” This Outline,
referred to as UL 2277, permits a 1,000 Volt rating and specifies safety and
performance requirements for cable intended to be installed within a tray or
raceway in the wind turbine. UL 2277 mandates that cables used in a cable tray
or raceway in the wind turbine must also meet all performance criteria of UL
1277, known as the “Tray Cable” standard.
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