NRG Product Manual
Hybrid XT Anemometer
HybridXT_Anemometer_Manual
Rev. 15
[email protected] | Page 18
02 January 2020
GROUNDING AND BONDING FOR OVER-VOLTAGE PROTECTION
Introduction
The purpose of this section is to outline the recommended practices for wiring, grounding, and bonding
of HXT turbine control sensors. The goal is to provide the best possible protection against direct and
indirect lightning damage for both the sensor and the interconnected turbine systems.
This section also details the internal construction of the sensor’s bonding and over-voltage protection.
This allows the wind turbine designer to coordinate the sensor grounding and Over Voltage Protection
(OVP) with the rest of the turbine’s Lightning Protection System (LPS).
Recommended Practices
The long-term reliability and the Electromagnetic Compatibility (EMC) performance of the sensor are
dependent on proper installation and connections. These recommendations could apply to any control
electronics or sensors, but are particularly critical for wind sensors because they are exposed on the top
of the nacelle.
The purpose of recommendations 1 through 5 is to provide shielding of the internal sensor electronics,
heater, and cabling so that they are protected to LPZ 1, per IEC 61400-24.
1 IEC 61400-24 classifies several Lightning Protection Zones (LPZ). LPZ 0A is exposed on the surface
of the turbine and is subject to direct lightning attachment. The turbine must provide air
terminals such as lightning rods to protect the sensors from direct lightning attachment. This
creates an area in LPZ 0B to mount the sensors.
2 Careful routing of the lightning down-conductor and coordination of the grounding and bonding
of the down-conductor(s) to the turbine’s LPS is required to minimize the energy coupled into
other systems such as the sensors. Provide maximum possible spacing between lightning down-
conductors and any control cabling or raceway. Do not route any other cabling or raceway
alongside the lightning down-conductors. These measures will minimize the coupling of lightning
electromagnetic pulse (LEMP) energy into other turbine systems.
3 The Sensor body is metal, and bonds to the sensor mounting mast. The mounting mast must be
metal. Take particular care to bond the sensor mounting mast to the turbine’s LPS in coordination
with the placement and bonding of the lightning air terminals and bonding of the turbine frame
and nacelle.
