Vaisala WAC151, Техническое описание, Страница: 6 / 9

Cross Arm WAC151
WAC151-T648en-1.1 Technical Reference
1996-09-25 1
1. INTRODUCTION
The WAC151 is a cross arm assembly to support the Vaisala WAA151
Anemometer, WAA251 Heated Anemometer and WAV151 Wind Vane. The
assembly consists of an anodized aluminum tube construction with a mounting
clamp for installation on top of a mast.
A water tight junction box is fitted to the cross arm, including a screw
terminal block for connection of the power and signal cables. Inside the
junction box, there is also a thermostat switch for controlling sensor shaft
heating for the standard '151-series sensors.
The junction box is equipped with four cable glands offering easy way for
earthing different cables. Typically, three cable glands are in use; two for
sensor cables one for signal cables. To ensure accurate wind speed
measurement in extreme winter conditions, WAA251 Heated Anemometer as
well as WHP25 Outdoor Mains Power Supply are recommended. The fourth
gland is reserved for the cable supplying heating power for heated
anemometer system.
It is important to notice that wiring instruction label inside the junction box is
for the standard '151-series sensors. However, when WAC151 is used with
WAA251 Heated Anemometer, small wiring changes are necessary. Please,
refer to the drawing WA35172.
The cross arm is installed in the north-south direction, with the wind vane
pointing to the north. The cross arm supports just one way to fix the sensors to
it ensuring correct assemblage.