Grounding And Bonding Hybrid Xt™ Sensors For Over-Voltage Protection - NRG Systems Hybrid XT Vane Product Manual

GROUNDING AND BONDING HYBRID XT™ SENSORS FOR OVER-VOLTAGE
PROTECTION
Introduction
The purpose of this document is to outline NRG Systems' recommended practices for wiring, grounding,
and bonding of Hybrid XT™ 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 document 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.
1. IEC 61400-24 classifies several Lightning Protection Zones (LPZ). LPZ 0
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 0 to mount the sensors.
B
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.
4. Use shielded or "screened" cable with high shield coverage for sensor cabling. We recommend
bonding the cable shield to the grounding system at both ends- at the sensor, and at the connection
to the turbine control system- to provide maximum protection from LEMP. However, see note 6
is exposed on the surface of
A